Prosiding II International Symposium “Innovations in Life Sciences” (ILS 2020)

Thus, the results of organoleptic assessment received from the check-lists of the paired comparison showed only the difference in the certain organoleptic parameters of the quality of the minced binary combinations made from meat with various amount of algae. Their organoleptic assessment by means of five-point grading scale allowed not only to assess the level of the quality of minced binary combinations, but to get the mathematical models that help determine the optimal values of the factor and C, W, T (concentration of the components, moisture content and duration of mincing). This research allows making a conclusion that the optimal values of the factors are: - algae content in minced compositions – 30% - moisture content – 50-60% - duration of mincing – 6 min. The results of organoleptic assessment of the quality of minced binary compositions made in accordance with the optimal parameters C, W, T (Figure 1) indicate on the different level of the quality of minced compositions form different meat raw materials. It is shown that the range of fluctuations in the assessment of their quality is from 92.6 to 97.6%. The comparative organoleptic assessment showed the different level of the quality of minced binary compositions, depending on the ration of algae: meat is improving by all the main parameters in the following order: y1, y3, y4, y5, y2. The best results are obtained in the combination beef + algae and duck + algae with the concentration 30% of algae. Further, these data are used in the development of the formulas of the functional chopped and minced meat products. Fig. 1. Organoleptic assessment of minced binary compositions 1. beef + algae; 2. duck + algae; 3. mutton + algae; 4. chicken + algae; 5. pork + algae 4 Conclusion The concentrations 10% and 30% of algae as a component of meat and plant system of chopped semi-finished products had no specific flavour and aroma during the tasting assessment. The increase in the content of the plant component up to 50% contributed to the increase in the product output and enhanced algae flavour. Therefore, it is advisable to study the chopped semifinished products with 10-30% algae content References 1. K.N. Nitsievskaya, O.K. Motovipov, and O.S Grushina, Vestnik of KrasGAU, 208–212, (2011) 2. S.V. Esaulov, Development of chopped meat semifinished products with calcium animal protein compositions (2009) 3. T.V. Pershakova, T.V. Pershakova, A.T. Vasyukova, T.S. ZHilina, T.V. YAkovleva, V.F. Puchkova, and I.A. Fedorkina, Food Industry, 319, 36–37, (2011) 4. A.T. Vasyukova, I.A. Leonov, V.L. Zaharov, and M.V. Vasyukov, Development and explanation of the technology of grilled semi-finished products (Lambert, Academic Publishing, Saarbrucken, Germany, 2016) 5. V.B. Chmykhalova, Vestnik of Kamchatka State Technical University, 66–78, (2012) 6. K.L. Konovalov, M.T. SHulbaeva, and O.N. Musina, Food Industry, 8, 10–12, (2008) 7. G. Levis, N. Stanley, and G. Guist, Algae and Human Affairs, 206–232, (1988) 8. S.T. Moe, K.I. Draget, and G. Skjak-Brake, Food Polysaccharides and their applications, 245–286, (1995) 9. A.T. Vasyukova and M.V. Vasyukov, International Journal of Innovative Studies in Sciences and Engineering Technology, 3, 15–18, (2017). 10. A. Moshkin, A.T. Vasyukova, and M. Novozhilov, Znanstvena misel journal, 1, 46–52, (2019) 11. B. Kabulov, S. Kassymov, Z. Moldabayeva, M. Rebezov, O. Zinina, Y. Chernyshenko, F. Arduvanova, G. Peshcherov, S. Makarov, and A. Vasyukova, Eurasia J Biosci, 14, 213–218, (2020) 12. M.A. Kolodko, L.A. Zabodalova, and V.N. Krasil'nikov, Low temperature food technologies in the XXIst century, 247–253, (2007) 13. A.T. Vasyukova, V.F. Puchkova, T.S. ZHilina, N.A. Kuharenkova, and I.G. Utarova, Educational medium today and tomorrow, pp. 168–171, (2016) 14. A.T. Vasyukova, A.V. Podkorytova, L.H. Vafina, N.I. Myachikova, and L.V. Dracheva, Fat and Oil Industry, 3, 22–24, (2015) 15. L.Kh. Vaphina, Substantiation of the complex processing of algae (Phaeophyta) while producing functional food products, (2010) 16. D.G. Oakenfuul, CSIRO Food Research Quart, 44, 49–50, (1984) 17. A.A. Slavyanskiy, M.B. Moyseak, V.M. Didenko, and L.S. Petova, Use of food SAW for intensification of technological processes of sugary sector, (2005) 18. E.V. Semenov, A.A. Slavyanskiy, and V.A. Karamzin, Chemical and Oil Machine building, 11, 7–10, (2014) 19. E. Kalakovskiy, Technology of minced fish meat. (Agropromizdat, Moskow, 1991) 4 BIO Web of Conferences 30, 01023 (2021) https://doi.org/10.1051/bioconf/20213001023 ILS 2020

20. S.S. Khruschev, A.M. Abaturova, A.N. D'yakonova, D.M. Ustinin, D.V. Zlenko, V.A. Fedorov, I.B. Kovalenko, G.YU. Riznichenko, and A.B. Rubin, Informatics and Modelling, 5, 47–64, (2013) 21. M.A. Nikitina, A.N. Zaharov, V.V. Nasonova, and A.B. Lisicyn, Theory and Practice of Meat Processing, 3, 63–77, (2017) 5 BIO Web of Conferences 30, 01023 (2021) https://doi.org/10.1051/bioconf/20213001023 ILS 2020

Creation of multi-component fruit and vegetable semi-finished products and confectionery on their basis with health properties Andreii Zahorulko1 * , Aleksey Zagorulko 1 , Kateryna Kasabova1 , and Irina Gordienko1 1 Kharkiv State University of Food Technology and Trade, Department of Processes, Devices and Automation of Food Production, 61051 Kharkov, Ukraine Abstract. A new method of production of multicomponent fruit and vegetable semi-finished products and sugar confectionery products, in particular pastilles, on its basis has been developed. The recipe of semifinished products is chosen taking into account the health properties, which consists of apples, pumpkins, beets, sea buckthorn and chokeberry. For concentration processes during the production of the semi-finished product, advanced apparatus based on a radiating flexible film resistive electric heater (RFFREH) is used. Rational modes of processing of vegetable raw materials are set for the developed apparatus. Studies of structural and mechanical properties of the proposed multicomponent fruit and vegetable pastes and purees are presented. Analysis of these structural and mechanical properties shows the advantage of multicomponent fruit and vegetable paste with apple puree – 30%, pumpkin – 20%, beets – 10%, sea buckthorn – 20% and chokeberry – 20%. The use of fruit and vegetable pastes in the technology of pastille gives the products a pleasant taste and aroma, due to which it is possible to use the paste as a natural flavor and dye, without the use of synthetic ones. The use of the developed fruit and vegetable paste in technologies of sugar confectionery, namely pastilles is offered. The optimal application of fruit and vegetable paste is 40% replacement of apple puree, which will provide a significant increase of physiologically functional ingredients in the product. 1 Introduction Deterioration of the ecological condition necessitates the provision of the population with functional food. Consumption of which will prevent diseases and aging of the body, by providing physiological action, will also have a beneficial effect on the target functions of the body, strengthening the health of the consumer. Therefore, one of the main tasks of the food industry is the production of semi-finished products of plant origin to increase the activity of the body's defenses and normal human life. After all, it is organic plant raw materials that contain a significant amount of vitamins, minerals and pectin, phytoncides, etc., and its processing allows to get a lot of different semi-finished food products and finished products. [1–3]. Analysis of publications allows us to conclude that a significant part of fruit or fruit and vegetable pastes are made in one or two components [4]. However, such pastes contain few vitamins, minerals and organic acids; color, aroma and taste are quite poor and aesthetically unattractive. The solution to this problem is possible by expanding the range of pasty semi-finished products by creating multi-component compositions of plant raw materials, which would be characterized by a significant natural content of biologically active substances and therapeutic and prophylactic properties [5]. * Corresponding author: [email protected] The main stage of paste production is the concentration of the appropriate puree to achieve a mass fraction of dry matter of 25…40% [6]. And it is during concentration, the duration of which in most evaporators can take about 400 minutes, providing significant losses of biologically active substances. Therefore, of great importance for the food industry is the development and implementation of efficient heat and mass transfer apparatus, the use of which will ensure the production of high quality pasty semi-finished products through the use of gentle temperatures and reducing the duration of the process [7]. The analysis of these materials allows to direct researches in the direction of the improvement of the production processes of health food products by reducing the temperature of concentration within – 45…65 °С [8], it will allow to increase qualitative indicators of the received semi-finished products and confectionery on their basis. At the same time, the introduction of pasty semi-finished products into confectionery recipes is promising for the creation of preventive products, which will expand the existing range [9–10]. There is a sufficient raw material base and scientific potential in Ukraine for the development of this area. Therefore, the task of developing new methods of production of semi-finished products with a high degree © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 01024 (2021) https://doi.org/10.1051/bioconf/20213001024 ILS 2020

of finishing from fruits and vegetables and expanding the range of food products on their basis with high organoleptic characteristics, nutritional and biological value, low cost and high profitability is urgent. 2 Experimental Experimental studies to improve the method of production of pasty semi-finished products with the high degree of finishing from fruit and vegetable raw materials and confectionery products on their basis were conducted on the basis of the Research Center "Latest biotechnologies and equipment for food production with high health properties" Kharkiv State University of Food and Trade (Ukraine). During the creation of multicomponent fruit and vegetable semi-finished products, the main raw materials were apple (Antonovka variety), pumpkin (Gilea Muscat variety), beetroot (Bordo variety), sea buckthorn (Galerit variety), chokeberry (Chornooka varieties), which have therapeutic and prophylactic properties, also purees and pastes on their basis. An apple with a high content of pectin substances, which provide interaction with other components, was used as the main part of the multicomponent semi-finished product. Thus, pumpkin is extremely rich in vital substances, antioxidants and vitamins. It contains vitamins C, B1, B2, E, PP and carotenoids. Pumpkin is an excellent source of dietary fiber, carbohydrates and beta-carotene (a powerful antioxidant that gives orange color to vegetables and fruits and is converted into vitamin A in the body). Consumption of foods rich in beta-carotene reduces the risk of some cancers, protects against asthma and other heart diseases, as well as delays the aging process and degeneration of the body. Pumpkin pulp improves the work of the gastrointestinal tract, promotes bile secretion, increases water and salt metabolism. Beet contains vitamins B1, B2, B5, C, pantothenic (vitamin B3) and folic acid, carotenoids; organic (oxalic, malic) acids, proteins and amino acids (lysine, valine, arginine, histidine, etc.). Finally, beet contains significant amounts of iron, manganese, potassium, calcium, cobalt. Cobalt is used for the formation of vitamin B12, which is synthesized by the intestinal microflora in humans and animals. In turn, this vitamin and folic acid are involved in the formation of blood cells – erythrocytes. In general, the complex of B vitamins has a positive effect on hematopoiesis, normalizes metabolic processes. The pulp of sea buckthorn fruit contains a large amount of organic acids, sugars, B vitamins (B1, B2, B6), C, E, K, iron, manganese, magnesium, boron, sulfur, silicon and more. Used for the prevention and treatment of sclerosis, strengthening blood vessels, normal nervous function. The use of a rotary film apparatus in the concentration process based on the radiating flexible film resistive electric heater (RFFREH) makes it possible to significantly reduce the duration of heat treatment of products and use low-temperature heat treatment, which preserves the nutritional value of natural raw materials. Chokeberry fruits contain vitamins C and PP, carotene, sugars, tannins and organic acids. Used in cardiovascular disease, hypertension and prevention of atherosclerosis, radiation and basal diseases. Beet and chokeberry were also taken as the natural dye. Blending experiments were done to substantiate the prescription composition of the fruit and vegetable paste. The selection of natural raw materials was carried out taking into account the content of biologically active substances, organoleptic properties and the influence of structural and mechanical parameters of each of the components on the consistency of the product. Apple was used as a structuring agent because it has a high content of pectin; pumpkin and beet – as a source of dietary fiber; beet due to its unique biochemical composition has a healing effect on the human body. The use of nontraditional vegetable raw materials, namely sea buckthorn and chokeberry allows to enrich the paste with biologically active substances and comply with the value of total acidity at the level of 3.3-3.7 pH [11]. The production of multicomponent fruit and vegetable pastes was carried out according to the proposed method, which differs from the accepted prescription components and modes of technological processing. The recipe ratio of fruit and vegetable components in multicomponent compositions is given in table І. According to the developed method, the fruits of sea buckthorn and chokeberry are washed, inspected, separately blanched with steam for 2…6 minutes in the multifunctional apparatus. The berries of sea buckthorn and chokeberry are rubbed to separate the skin and stones. Obtained after rubbing skin with pulp residues are boiled for 5-10 minutes, while the ratio of the mass of the skin and bones with the pulp residues to the mass of water is 1:0.5- 1:0.7. The obtained mass is rubbed. Apple, pumpkin and beet puree is prepared according to the current technology for the production of fruit and vegetable purees. Then combine the mass of sea buckthorn and chokeberry, rubbed mass of the decoction of the skin and stones of these berries, apple, pumpkin and beet puree and mix. The fruit and vegetable mass, preheated to a temperature of 40-50 °C, is concentrated in a rotary film apparatus (RFA) (Fig. 1) at a temperature of 50-60 °C to dry solids content of 28-30% for 1-1.5 min. Under the conditions of final concentration, the pasty semi-finished product is packaged at a temperature of 56-59 °C, sealed, pasteurized and labeled (table 1). Table 1. Recipe ratio of fruit and vegetable components in multi-component compositions Component composition Composition (sample) 1а 1b 1c Apple 40 30 20 Pumpkin 25 20 15 Beet 5 10 15 Sea buckthorn 15 20 25 Chokeberry 15 20 25 Control, % 100 100 100 2 BIO Web of Conferences 30, 01024 (2021) https://doi.org/10.1051/bioconf/20213001024 ILS 2020

3 7 6 5 2 4 8 1 9 10 Fig. 1. 1. Advanced rotary film apparatus: 1 – a working chamber; 2 – a radiating flexible film resistive electric heater with insulating surface (RFFREH); 3, 4 – pipes for pumping and discharging of raw materials; 5 – a secondary steam discharge pipe; 6 – a separation space; 7 –an electric motor; 8 – a rotor; 9 –a hinged blade; 10 – a distribution ring. To establish the mechanism and patterns of the processes of formation, deformation and destruction of the structure, changes in the structural and mechanical properties of puree-like compositions according to the recipe ratio were studied. Apple raw material was used as a control sample. The results of research of samples of fruit and vegetable raw materials for pasty semi-finished product are shown in Fig. 2. As can be seen from Fig. 2 the shear stress for all types of fruit and vegetables differs from zero and is for apple puree q0 = 42 Pa, pumpkin – 12, beet – 30, sea buckthorn –3.5, chokeberry – 15 Pa. All samples have a shear stress and do not begin to flow immediately after the increase in voltage, ie they belong to imperfectly plastic solids. The increase in the shear stress for all fruit and vegetable raw materials is primarily due to the higher content of dry solids and pectin Fig. 2. Shear characteristics of fruit and vegetable raw materials: – apple, – pumpkin, – beet, – chokeberry, – sea buckthorn. The results of the maximum value of the effective viscosity of the obtained blended paste ηef (Pa ∙ s) were also obtained for the samples: 1a – 154; 1b – 148; 1c – 141 and control – 127, respectively (Fig. 3). Thus, the proposed prescription ratios of fruit and vegetable components in multicomponent compositions lead to an increase in the effective viscosity of 10-18% compared to the control (apple paste), which has a positive effect on strengthening the structure of the pasty semi-finished product. Analysis of structural and mechanical properties and organoleptic evaluation shows the advantage of multicomponent fruit and vegetable paste with the introduction to the 30% apple puree pumpkin – 20%, beet – 10%, sea buckthorn – 20% and chokeberry – 20% (sample 1b) to the total weight of raw materials. The introduction of pumpkin and beets in large quantities gives an unpleasant specific taste, and in a small amount of sea buckthorn and chokeberry reduces the nutritional value of the product. Further use of the developed multicomponent fruit and vegetable paste in the technologies of sugar confectionery, namely pastilles. It was previously established that it is optimal to apply a multicomponent paste in the amount of 40% with the replacement of apple puree, thereby providing a significant increase in physiologically functional ingredients in the obtained products. Taking into account the results of research on the example of the recipe of the pastille "Vitaminka" on the basis of the obtained multicomponent vegetable paste (Table II). An increased number of physiologically functional ingredients in the experimental product, compared with the traditional pastille "Vanilla", is found (Table III) As can be seen from the above data, the introduction of fruit and vegetable paste can significantly increase the content of confectionery: dietary fiber, organic acids, vitamins (groups B, PP, C, E), phenolic compounds and minerals (magnesium, potassium, phosphorus, iron, calcium). In addition, in terms of the formulation of blended fruit and vegetable paste, the products get a taste and aroma, confirming the relevance of the use of organic pastes as natural flavors and dyes without the use of their synthetic substitutes. Fig. 3. Shear characteristics of fruit and vegetable raw materials: Complete rheological curve of multicomponent fruit and vegetable pastes: apple control, sample 1b, sample 1a, sample 1c 5 25 45 65 85 105 125 10 20 30 γ, s –1 σ, Pа 0 , s -1 20 40 60 80 100 120 140 160 0 5 10 15 20 , Pa s 3 BIO Web of Conferences 30, 01024 (2021) https://doi.org/10.1051/bioconf/20213001024 ILS 2020

Table 2. Recipes Of Pastille "Vitamin" With The Addition Of Fruit And Vegetable Paste Name of raw materials and semifinished products Mass fraction of dry solids,% Pastille «Vitaminka» Per 1 ton of finished products in natural mass in dry solids White sugar 99,85 686,0 685,0 Powdered sugar 99,85 4,5 44,9 Syrup 78,0 107 83,5 Apple puree 10,0 366,0 36,6 Egg white 12,0 23,3 2,8 Agar 85,0 6,0 5,1 Lactic acid 40,0 4,2 1,7 Multicomponent paste 33,0 184,8 54,9 Together - 148,31 92,03 Output 85,0 1000,0 850,0 Table 3. Nutritional Value Of Pastille With The Addition Of Fruit and vegetable Paste Indicator Consumpti on norm Pastille "Vanilla"(contr ol) Pastille "Vitamink a" Caloric content, kcal 324,0 210,0 Proteins, g / kg 1,5-2,5 0,5 0,55 Fat, g 45-65 0,5 0,5 Carbohydrat es, g 150-260 80,0 54,5 Dietary fiber, g 25-35 0,8 1,8 Vitamins B vitamins, mg 1,0-2,6 0,01 0,03 Vitamins PP, mg 20,0 0,02 – Vitamin C, mg 75,0-150,0 - 3,0 Vitamin E, mg 10,0 - 0,98 Minerals Sodium, mg 1300 16,0 18,5 Potassium, mg 2500 55,0 127,4 Calcium, mg 1000 21,0 18,0 Magnesium, mg 400 7,0 11,5 Phosphorus, mg 800 11,0 15,3 Iron, mg 10,0-20,0 1,6 1,6 3 Conclusion A method for the production of a multicomponent fruit and vegetable semi-finished product of a high degree of finishing has been developed and the influence of the mass fraction of each component on the change of structural and mechanical properties of the proposed prescription ratios of pastes has been established. Analysis of these structural and mechanical properties and organoleptic evaluation shows the advantage of multicomponent fruit and vegetable paste with a content of puree with 30% apples, pumpkin – 20%, beets – 10%, sea buckthorn – 20% and chokeberry – 20 The maximum value of the effective viscosity of the obtained blended pastes (ηef) for the samples: 1a – 154 Pa∙s; 1b – 148 Pa∙s; 1c – 141 Pa∙s and control – 127 Pa∙s, respectively, was determined. Thus, the introduction of other components from 60 to 80% to apple paste in accordance with the prescription ratio leads to an increase in the effective viscosity of 10…18%, which has a positive effect on strengthening the obtained structure of the pasty semi-finished product. The recipe of the pastille "Vitaminka" with the addition of multi-component fruit and vegetable paste (apple, pumpkin, beet, sea buckthorn and chokeberry) was developed. The introduction of vegetable paste can significantly increase the content of dietary fiber, organic acids, vitamins, phenolic compounds and minerals. Also, with the addition of fruit and vegetable pastes, the samples get taste and aroma, due to which it is possible to use the paste as the natural flavor and dye. Also developed fruit paste can be used as a vitamin supplement in therapeutic and prophylactic nutrition, filler and thickener in various sectors of the food industry, such as confectionery and dairy, as well as for cooking and beverages in catering and at home. Further research is planned to be directed towards determining the optimal modes of preliminary heat treatment of plant raw materials in order to improve the quality of the obtained semi-finished products and reduce wasteUse a two-column format, and set the spacing between the columns at 8 mm. Do not add any page numbers. References 1. A. O. Haiazova, L. S. Prokhasko, M. A. Popova, S. V.Lukynykh, B. K. Asenova, Molodoi uchenyi, 19, 189–191, (2014) 2. N. V. Mykriukova Molodoi uchenyi, 12,. 90–92, (2012) 3. T. Bucher, K. van der Horst, M.Siegrist Appetite, 60, 74–80, (2013) 4. Y. Yorozu, M. Hirano, K. Oka, and Y. Tagawa, IEEE Transl. J. Magn. Japan, 2, 740–741, (1987) 5. L. Huang, L. Ba, X. Zhang, Sh. Gong, Food Quality and Preference, 73, 266–275, (2019) 6. O. Cherevko, V.Mykhaylov, О. Zagorulko, A. Zahorulko, Eastern-European Journal of Enterprise Technologies. 2, 11–17 (2018). 7. L. Kiptelaya, A. Zagorulko, A. Zagorulko, EasternEuropean Journal of Enterprise Technologies, 2,. 4– 8 (2015). 8. A. Zahorulko, A. Zagorulko, N. Fedak, S. Sabadash, D. Kazakov, V. Kolodnenko. Eastern-European Journal of Enterprise Technologies, 6, 6−13 (2019) 9. А.О. Bashta, В.В. Kovalciuk, Harciova promislovisti,. 16, 37–41, (2014) 4 BIO Web of Conferences 30, 01024 (2021) https://doi.org/10.1051/bioconf/20213001024 ILS 2020

10. N.F. Tuz, M.V. Artamonova, Engineering of processing and food production, 1, pp. 32–37, (2016) 11. G.O. Magomedov, A.A. Juravliov, I.V. Plotnikova, T.A. Sheviakova, Vestnik VGUIT, 1, 126–127 (2015) 5 BIO Web of Conferences 30, 01024 (2021) https://doi.org/10.1051/bioconf/20213001024 ILS 2020

Purification of water and fertile soil with bentonite-like clays of the Belgorod Region Alexandr Vezentsev1* , Natalia Volovicheva1 , Svetlana Korolkova1 , Lidiia Peristaya1 , Vitaliy Milyutin2 , Igor Korolkov1 1Belgorod National State Research University, 308015 Belgorod, Russia 2Frumkin Institute of Physical chemistry and Electrochemistry Russian academy of sciences Sciences, 119071 Moscow, Russia Abstract. This paper presents the results of a comparative assessment of the effectiveness of sorption purification of aquatic medium and fertile soils using native forms of bentonite clays of deposits in the Belgorod region (Russia) from heavy metal ions (Cu2+, Fe3+ , Cr3+, Pb2+) and radionuclides ( 137Cs, 85Sr, 233U и 239Pu). It was revealed that during the sorption of heavy metal ions (Cu2+, Fe3+ и Cr3+) from model water systems, the most absorbing activity is shown by the natural clays of the Polyana and Nelidovka deposits, which have almost the same ability to absorb heavy metal ions. The purification efficiency of the model aqueous solutions from these cations taken at an initial concentration of 0.1 mmol/l reaches 95%. It was established that the natural clay of the Polyana deposit is also an effective sorbent for the purification of solutions from cesium radionuclides. In terms of sorption ability, the studied sample is 5 times superior to natural clinoptilolite, which is most often used to purify solutions from radiocesium.. It was revealed that with an increase in the amount of added sorbents, the detoxification effect is increased, that is, the content of heavy metals in the green mass decreases. 1 Introduction Pollution of the environment by heavy metals and pathogens is always potentially dangerous due to their introduction from the hydro- and lithosphere through metabolic and trophic chains into living organisms, including humans [1]. In view of the imperfections of treatment systems and structures, various pollutants enter water bodies, deteriorating their sanitary condition and causing the need for special deep purification of water before using it for household and drinking purposes and some industrial purposes. In addition to water purification, another vital problem is the cleaning of soil from heavy metals such as lead, copper, etc. Heavy metals in the soil are of both natural and anthropogenic origin. For example, one of the anthropogenic sources of copper is poisonous chemicals used for a long time in vineyards. Further, through the food chain, soil - plants - animals - human heavy metals enter the human body, causing a number of negative effects [2]. Thus, a wide range of harmful and toxic substances entering the environment, and, as a result, into the human body and animals with aerosols, water and food, determines the need to search for and create materials with pronounced sorption selectivity to heavy metals, radionuclides, pathogenic microorganisms and other pollutants. As world practice shows, the most promising and economical method of cleaning the components of the biosphere is the sorption method. The efficiency of purification by this method reaches 80 - 95% [3-5]. * Corresponding author: [email protected] Currently, bentonites [6-7] are successfully used as adsorption active materials in solving environmental problems. Bentonite-like clays are widespread in the Belgorod region (Russia) in Paleogene deposits. Bentonites are confined to the deposits of the Kiev retinue, folded (from top to bottom) with clays, marls and clay aleurites, which lie at a small (0-15 m) depth. Sediment capacity reaches 25-30 m [8]. The purpose of this work was to study the efficiency of purification of aquatic medium and fertile soils from ions of heavy metals and radionuclides when using bentonite-like clays selected from various deposits and sites of the Belgorod region (Russia) as sorbents. 2 Research materials and methods On the territory of the Belgorod region there are clay materials, a feature of which is the predominance of the montmorillonite-hydromicaceous component, as well as the calcite mineral. In the present work sorption properties of natural forms of clays of fields of the Belgorod region are investigated: Polyana (Shebekinsky district), Nelidovka (Korochansky district), Orlovka and the Top Olshanets (Belgorod district), Sergiyevka (Gubkinsky district) in relation to ions of heavy metals (Cu2+, Fe3+ , Cr3+, Pb2+) and radionuclides (137Cs, 85Sr, 233U and 239Pu). Earlier, the authors of this work established the peculiarities of the material composition and textural © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

characteristics of the examined samples of these deposits [9-11]. According to the results of the analysis of the mineralogical composition, the clays of all tested deposits and locations are polymineral systems. The main rockforming minerals in them are montmorillonite, illite, kaolinite, clinoptilolite, feldspar (orthoclase and anorite), as well as low-temperature trigonal quartz and calcite. As an example, Figure 1 shows an electronic micrograph of a montmorillonite particle from the clay of the Polyana deposit (Shebekinsky district), obtained by us using a JEM - 2100 transmission electron microscope (JEOL, Japan). The figure also shows the microdifraction pattern and the energy dispersion spectrum of this particle. Fig.1. Montmorillonite from the clay of the Polyana deposit (Shebekinsky district): a) microphotography; b) microdifraction pattern; c) energy dispersion spectrum The particles of this mineral in the preparations have a vague cloud-like appearance, which is typical of montmorillonite. Their size is from fractions to 3-5 microns. All montmorillonite particles have a polycrystalline structure, which is manifested both in their morphology and in the microdifraction patterns they form, which, as a rule, have a circular nature of the distribution of reflexes hK0 (Figure 1 b). Many particles have numerous bends and bends characteristic of this mineral at the edges, favorable for obtaining microdifraction paintings with reflexes 00 l [12, 13] On the energy dispersion spectrum of montmorillonite particles from the clay of the Polyana deposit (Fig. 1c) there are peaks: Si, O, Al, Ca and Fe, the content of these elements is 51.8, respectively; 33.9; 9.52; 4.3 and 0.4 wt%, which indicates a calcium variety of this mineral. By the method of adsorption luminescent analysis based on cation-exchange adsorption of organic dyesphosphors by clay with formation of coagulate of organclay complex, we determined mass fraction of sorption active mineral montmorillonite in examined samples (table 1). Table 1. Content of sorption active montmorillonite in natural clays, wt% The absorption capacity of natural clays with respect to iron (III), chromium (III) and copper (II) ions was determined using model water systems by constructing sorption curves using a variable concentration method. For this purpose, a series of model solutions of salts containing cations Fe3+, Cu2+ and Cr3+ were prepared. In order to prevent hydrolysis, model aqueous systems with a specified metal ion concentration of 0.1 mmol/l were acidified with a sulfuric acid solution until the pH value was maintained at 3.0 - 3.3. The experiment was carried out under static conditions at a temperature of 25 ° C. The duration of the isothermal step was 60 minutes. The solid/liquid phase ratio was 1:100. At the end of the process, the suspensions were filtered. The residual concentration of cations in the solution was determined photometrically at the appropriate wavelength using a Spekord-50 device. Radionuclide sorption experiments were carried out under static conditions by mixing a slurry of ground sorbent with an aliquot of aqueous solution for 48 hours. The liquid and solid phases were then separated by filtration through a “Blue ribbon” paper filter. In the resulting filtrate, the specific activity of the radionuclide was determined and the distribution coefficient (Kd) of the corresponding radionuclide was calculated by the formula (1): Kd = ((ао - ар)/ар)×Vр/mс (1) The deposit from which the clay sample was taken Montmorillonite content, wt% Yablonevo 40.0 – 45.0 Sergievka 47.0 – 52.0 Nelidovka 45.0 – 49.0 Top Olshanets 40.0 – 45.0 Orlovka 35.0 – 40.0 Polyana 58.0 – 65.0 2 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

where is ао, ар - initial and equilibrium specific activity of radionuclide in solution, Bq/dm3 Vр – liquid phase volume, sm3 ; mс – mass of a sorbent, g. In studying the sorption of radionuclides, tap water of Belgorod composition was used as a liquid phase: total stiffness - 4.19 mg-eq/dm3, calcium - 67.8 mg/dm3, magnesium - 9.5 mg/dm3, total salt content - 720 mg/dm3 , pH = 7.1. Before starting the experiments, indicator amounts of radionuclides 137Cs, 85Sr, 233U, 239Pu in an amount of 105 -106 Bq/dm3 were added to the solutions. Determination of lead and copper in soils and clays was carried out by atomic absorption spectrometry according to the standard method [14]: gross content - chemical decomposition of samples with nitric acid (1:1); mobile acid-soluble forms - extraction with 1 n nitric acid; mobile forms available to plants - extraction with acetateammonium buffer solution with pH = 4.8. 3 Discussion of results It was established that when using natural clays of investigated deposits of the Belgorod region as sorbents of heavy metal ions from model aqueous solutions, the highest sorption rate is observed in the first 5 minutes of exposure. Table 2 shows the efficiency of extraction of ions Cu2 , Fe3 and Cr3 from aqueous solutions by experimental sorbents (sorption duration was 60 minutes). Table 2. Efficiency of sorption of heavy metal ions by natural clays Comparative analysis of Table 2 showed that the efficiency of cleaning model aqueous solutions from heavy metal ions with a concentration of 0.1 mmol/l by natural clays of the Polyana and Nelidovka deposits reaches 95%. As for Oryol clay, when used as a sorbent, the purification efficiency of model aqueous solutions is relatively low. It is inferior to Polyanskaya and Nelidovskaya clays on the 20 - 30%. The residual concentration of iron (III) ions in the model solution during sorption purification by Oryol clay is 0.034 mmol/l (1.90 mg/l), chromium (III) ions - 0.033 mmol/l (1.72 mg/l), and copper (II) ions - 0.029 mmol/l (1.86 mg/l). It was established that during the sorption of heavy metal ions (Cu2 , Fe3 and Cr3 ), the most sorption activity is shown by the natural clays of the Polyana and Nelidovka deposits, which have almost the same ability to absorb heavy metal ions. Top Olshanets clay is inferior in its sorption ability to Polyansky and Nelidovsky samples 1.5- 2 times. Reduction of concentration of metal ions in model aqueous solutions occurs as a result of sorption, epitaxial-destructive, ion-exchange processes, as well as due to formation of hardly soluble hydroxides. Experimental work to study the sorption characteristics of the natural clay of the Polyana deposit in relation to the radionuclides 137Cs, 85Sr, 233U and 239Pu was carried out in the laboratory of chromatography of radioactive elements of the Institute of Physical Chemistry and Electrochemistry named after A.N. Frumkin RAS. Specific activity of radionuclides in solutions was determined by direct radiometric method using the spectrometric complex СКС-50М (Green Star Technologies, Russia). Table 3 shows the values of the distribution coefficients (Kd) 137Cs, 85Sr, 233U and 239Pu on the test samples. For comparison, in similar conditions, the Kd values of the above radionuclides were determined on the clinoptilolite of the Shivertuyskoye deposit (Chita region), which is currently used as a radionuclide sorbent. Table 3. Values Of distribution coefficient (kd) of radionuclides 137cs, 85sr, 233u And 239pu during sorption from tap water on natural clay of polyana deposit and on clinoptilolite Sorbetn type Kd 137Cs, sm3 /g of radionucleides 137Cs 85Sr 233U 239Pu Clay of Polyana layer (6.0±0.4) ×104 330± 20 29 ± 3 85±8 Clinoptilotite (1.1±0.2) ×104 580± 40 90±7 97± 6 It has been found that natural clay is an effective sorbent for cleaning solutions from cesium radionuclides. In terms of sorption ability, the studied sample is 6 times superior to natural clinoptilolite, which is most often used to purify solutions from radiocesium. The sorption of strontium, uranium and plutonium radionuclides on the studied clay sample proceeds much worse. The values of Kd during sorption of these radionuclides from tap water are 3 orders of magnitude lower than the corresponding values during sorption of cesium. Low sorption values of Sr are related to competition of Ca ions present in tap water [15]. The best sorption characteristics with respect to 85Sr are natural clinoptilolite. Low sorption of U is due to the fact that U in tap water is in the form of strong anionic tricarbonate complexes [16], which are poorly absorbed on cation-exchange groups of clays. Low sorption characteristics of the analysed samples with respect to 239Pu are explained by the fact that Pu in tap water is in fully hydrolyzed form [17]. Partial absorption of Pu is associated with adsorption of its colloidal forms on the surface of the sorption material. Based on the experimental work carried out on the use of investigated natural clays of the Belgorod region in the process of purification of aqueous media from ions of heavy metals and radionuclides, it was found that the most promising material is a sample taken from the Polyana deposit. Therefore, this sorption active material was chosen by us to continue research aimed at studying the Layer Sorption efficiency beyond 60 min., % Cu2+ Fe3+ Cr3+ Polyana 95 95 95 Nelidovka 94 95 94 Top Olshanets 72 90 90 Orlovka 70 63 67 3 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

efficiency of cleaning the fertile soil layer from ions of heavy metals (copper and lead). Also, for this purpose, we tested a sample of bentonite-like clay taken from the Sergievka deposit of the Gubkinsky district of the Belgorod region. The experimental work was carried out in two stages. At the first stage, laboratory studies were carried out using buffer soil extracts. The initial concentration of mobile forms of copper and lead available to plants in the buffer extract from a soil sample, established by atomic absorption spectrometry, was: Cu2+ 2.0 mg/kg, Pb2+ 1.20 mg/kg. Sorption was carried out at constant temperature (20С) under static conditions for 90 minutes. Sorbent (clay) was taken in an amount of 0.1; 0.5; 1.0; 3.0 and 5.0 g per 50 ml buffer extract. The results of the soil clay treatment are shown in Table 4. The results shown in Table 4 show that with an increase in sorbent weight from 0.1 g to 5.0 g, the degree of purification of the buffer extract by clay taken from the middle layer from ions Cu2 increases from 45.5 to 95.5%, and from ions Pb2+ - from 33.3 to 83.3%. The degree of purification of the buffer extract with clay taken from the lower layer with the same increase in sorbent weight increased from 54.5 to 95.5% (for Cu2 ) and from 33.3 to 83.3% (for Pb2+). Table 4. Degree of cleaning of soil buffer clay of Sergievka deposit Sorbent mass, g Center, wt % Lower layer, wt % Cu2+ Pb2+ Cu2+ Pb2+ 0.1 45.5 33.3 54.5 33.3 0.5 70.5 45.8 68.2 58.3 1.0 72.3 58.3 79.5 58.3 3.0 86.4 75.0 87.3 83.3 5.0 95.5 83.3 95.5 83.3 Therefore, purification of the buffer extract from copper ions by these clays is more effective than from lead ions. Studies have shown that the optimal ratio of clay to soil is 1:5. At this ratio, the degree of soil purification with clay is: for copper ions 95.5 wt%, for lead ions 83.3 wt%. The second stage of experimental work consisted in conducting experimental testing studies in the field and was aimed at studying the growth intensity and yield of radish and corn plants of the F1-Sandrina variety, depending on the dose of clay sorbents previously introduced into the soil. Studies with radishes were carried out by the vegetation method. Universal peat grunt is used as soil nutrient medium. Before the start of sowing, the soil peat was pre-infected with copper ions, which were introduced into the soil as an aqueous solution of copper sulfate pentahydrate - CuSO4∙5H2O at a rate of 198 mg of Cu2+ ions per square meter. As a sorbent, clay of the Polyana deposit of the Belgorod region was added to the soil at a rate of 90 g/m2. The experiment was carried out according to a scheme comprising three test variants: 1. "clean" soil (control); 2. soil copper salt; 3. soil salt copper clay. Table 5 shows the total (gross) copper content of soil samples and the content of mobile copper compounds as well as the pH of the three soil samples. The studies carried out yielded the following results. The total (gross) copper content in the initial sample No. 1 studied, in the so-called "pure" soil is 69.0 mg/kg or 6.9 10-3 mass%. According to V.V. Kovalsky, the normal copper content in soils is (1.5-6.0) 10-3 wt% [18]. Therefore, the gross copper content of the original peat soil sample (No. 1) is insignificantly higher than normal. Content of mobile copper compounds extracted by acetate-ammonium buffer solution in initial sample corresponds to maximum permissible concentration of 3 mg/kg [19]. Table 5. Copper content in three soil sample Experiment variant Gross copper content, mg/kg Mobile copper compounds, mg/kg рН of soil № Soil type The extracting solution acetateammonium buffer solution with рН 4.8 1н. НNO3 1 «pure» soil 69 3.0 5.1 6.27 2 soil+Cu2+ 170 3.9 22.6 5.91 3 soil+Cu2+ + clay 110 2.6 19.0 6.26 When copper sulfate was added to the soil in the above amount, the gross copper content increased from 69.0 to 170.0 mg/kg (sample No. 2). After the clay was added to the soil artificially contaminated with copper, the gross copper content decreased to 110.0 mg/kg (sample No. 3), and the content of mobile copper compounds decreased significantly: from 3.9 to 2.6 mg/kg. Thus, the investigated clay of the Polyana deposit, taken in the indicated amount (90 g/m2 ), allows reducing the content of mobile forms of copper in contaminated soils to a concentration below the maximum permissible. Similar changes in copper content are observed when it is extracted from the soil 1N. nitric acid. It follows from Table 4 that clay reduces the concentration of hydrogen ions and accordingly increases soil pH by cation exchange. Therefore, the application of clay is a positive factor in the fight against acidification of fertile soil. We have shown that excessive copper content in soil adversely affects the growth and development of radishes (Table 6). When visually evaluating the appearance of the radish, it was found that the plants dry, the leaves are coiled, have a pale color, chlorosis is observed. The formation of root crops did not happen. Especially clearly, these features are noted with soil sample No 2, where the copper content is greater than in other samples. They have a smaller stem height and leaf area, as illustrated in Table 6. This is due to the higher content of mobile, water-soluble forms of copper available to plants. 4 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

Table 6. Effect Of Cu 2+ And Sorption Active Clay Ions On Stem Height And Radish Leaf Area Experiment variant Content of mobile forms of copper in soil, mg/g Height of a stalk, cm Area of a leaf, cm2 1 «pure» soil 3.0 5.6 11.09 2 soil + Cu2+ 3.9 4.8 9.00 3 soil + Cu2+ +clay 2.6 5.5 10.80 At the same time, field experience was laid to study the effect on corn of the variety "F1 - Sandrina" of natural nanostructured sorption active materials based on clay rocks of the Belgorod region according to the scheme presented in Table 7. Table 7. Field Experience Laying Diagram For Assessment Of Clay Sorbents Efficiency Experiment variant Characteristic of basic data 1 Control (corn planted) 2 Corn sorbent (Polyana clay in the amount of 51 g/m2 ) 3 Corn sorbent (clay of Polyana deposit in the amount of 90 g/m2 ) 4 Corn sorbent (clay of Polyana deposit in the amount of 129 g/m2 ) 5 Corn sorbent (clay of the Sergievka deposit (middle layer) in an amount of 51 g/m2 ) 6 Corn sorbent (clay of the Sergievka deposit (middle layer) in the amount of 90 g/m2 ) 7 Corn sorbent (clay of the Sergievka deposit (middle layer) in the amount of 129 g/m2 ) 8 Corn sorbent (clay of Polyana deposit in the amount of 90 g/m2 ).+ solutions of salts CuSO4 ∙5Н2О with concentration of Cu+2 ions 198 mg/m2 and Pb (СН3СОО)2∙3Н2О with concentration of Pb+2 ions 185 mg/m2 9 Corn + sorbent (clay of the Sergievka deposit (middle layer) in the amount of 90 g/m2 ).+ solutions of salts CuSO4 ∙5H2О with concentration of ions Сu +2198 mg/m2 and Pb (СН3СОО)2∙3Н2О with concentration of ions Pb+2 185 mg/1m2 . 10 Corn + sorbent activated carbon Agrosorb -1 20g/m2 solutions of salts CuSO4∙5H2O with concentration of ions Cu+2 198 mg/m2 and Pb (СН3СОО)2∙3Н2О with concentration of ions Pb+2,185 mg/m2 . In the process of experimental testing, the growth intensity of the above-ground part of plants was observed, depending on the dose of the sorbent previously introduced into the soil. A control measurement of the height of the aboveground part of corn plants of the F1 - Sandrina variety, produced 2 months after planting (phase of the fifth to sixth sheets), made it possible to construct the growth diagram shown in Figure 2. Analysis of the data of the diagram shows that the preliminary introduction of sorbents developed on the basis of clays of the Belgorod region (Polyana field - sections 2-4 and 8; Sergievka deposit - areas 5-7 and 9) has a visible positive effect on the process of corn growth. The above-ground parts of plants grown in these areas are on average 2-2.5 times higher than those grown in the protective zone and in the control area. Additional contamination of the soil with cations Cu2+ and Pb2+ produced at sites 8, 9 and 10 did not cause inhibition of corn, therefore, it can be concluded that the sorbent added to these sites "bound" the cations Cu2+ and Pb2+ into forms inaccessible to corn. Fig. 2. Diagram of the average height of corn plants (phase of the fifth to sixth sheets), depending on the dose of sorbent previously introduced into the soil, site numbers according to the field experience laying act It is worth noting that the activated carbon Agrosorb1 (site 10), introduced for the purpose of comparison as a sorbent, also showed a positive effect on plant growth. However, the height of the aboveground part of corn in this area is 5-10% lower than that of corn in areas where clays of the Belgorod region were used as a sorbent At the stage of crop maturity, an assessment of the quality of the products obtained as a result of experimental field testing of the addition of detoxicant additive based on the developed sorption active clays of the Belgorod region is given. The weight of the plant mass, as well as the content of heavy metals (Cu2+ and Pb2+) in the cobs and stem-leaf part were evaluated By atomic adsorption spectroscopy, the content of Cu2+ and Pb2+ cations in the green mass was determined, as shown in Table 8. Analysis of Table 8 shows that both copper cations and lead cations in the maize stem and leaf are lower than the allowable level of these metals in crop production. However, the content of Cu2+ and Pb2+ in the plant samples grown at the control site is slightly greater than in the sites where the clays were previously added. As the amount of added sorbents increases, the detoxification effect is enhanced, i.e. the content of heavy metals in the green mass is reduced The obtained data showed that it is most effective to bind heavy metal cations to a form of clay of the Polyana deposit inaccessible to plants. In particular, this is noticeable when analyzing the content of Cu2+ and Pb2+ 5 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

cations in plant samples grown at sites previously infected with these metals (sites 8 and 9). The content of copper in the stem-and-leaf part of corn removed from the area where said clay was used as a detoxicant additive (section 8) is almost 5 times lower than in the green mass of corn removed from the area where the sorbent based on the clay of the Sergievka deposit (section 9) was previously introduced, and the lead content is 1.2 times less in the same samples. The active coal sorbent Agrosorb-1 also absorbs copper and lead cations but is less effective than clays. Table 8. Average content of cations Cu 2+ And Pb 2+ In the green corn mass of the upper stem with leaves No. of the area from which the sample was taken Metal cation content in dry matter, mg/kg Content of metal cations in natural substance, mg/kg4 Mass fraction of moisture, % Cu2+ Pb2+ Cu2+ Pb2+ Control 4.15 2.50 3.465 2.088 16.50 2 3.10 2.10 2.818 1.909 9.10 3 3.10 1.85 2.809 1.676 9.40 4 2.70 2.10 2.468 1.919 8.60 5 2.20 1.50 1.839 1.254 16.40 6 3.20 2.10 2.861 1.877 10.60 7 1.35 1.60 1.230 1.458 8.90 8 1.95 1.70 1.775 1.547 9.0 9 6.10 1.85 5.423 1.645 11.10 10 3.85 2.30 3.176 1.898 17.50 The cation content of Cu2+ and Pb2+ in the cobs of corn grown in the test site is shown in the Table 9. Table9. Average content of cations Cu2+ And Pb2+ in the green corn mass of the upper stem with leaves The data presented in Table 9 confirm the conclusions of the analysis of Table 8. However, it is noteworthy that the Cu2+ content of corn grains is higher than that of green mass. This can be explained by the fact that the mass of copper cations is relatively low and therefore their migration together with other solutes from the soil along the conducting system of the plant is easier, unlike lead cations. It should be noted that the absorption capacity of the sorbent increases with increasing concentration of heavy metal cations. Thus, the studies conducted show that the bentonitelike clays of the Polyana deposit are most effective for cleaning the soil from copper and lead ions. The optimal amount of sorbent is 90 g, introduced per 1m2 , or 900 kg per 1 ha of soil. 4 Conclusion The presented results of experimental studies made it possible to conclude that the most promising universal sorption active material for cleaning such components of the biosphere as water and soil is the natural bentonitelike clay of the Polyana deposit of the Shebekinsky district of the Belgorod region. Said native clay exhibits good absorbency to heavy metal ions and radionuclides, since it is characterized by a higher content of montmorillonite mineral, compared to samples of other clays of the Belgorod region. It is possible to propose the following mechanism of binding heavy metal cations with sorption active montmorillonite, based on possible substitution of mobile cations in structure of its crystal lattice with ions of heavy metals with close ion radius, for example, K+ (0.133 nm) at Pb2+ (0.126 nm), Na+ (0.098 nm) at Cu2+ (0.08 nm) [20, 21]. Absorption of metal ions by montmorillonite occurs both by cationic exchange in inter-packet positions and by adsorption on the outer surface, primarily on the end portion of the laminated crystals, having the output of the active centers, which are uncompensated bonds. References 1. A.V. Skalny, M.: Publishing house “ONICS 21 century,”, 216, (2004) 2. T.V. Pleteneva, “Toxicological chemistry,” (GEOTAR - Media, Moscow, p.512, 2005) 3. I.N. Lozanovskaya, D.S. Orlov, L.K. Sadovnikova, “Ecology and protection of the biosphere during chemical pollution,” M.: Higher School, p.168. (1998) 4. L.F. Goldovskaya, Environmental Chemistry - 2nd edition, (World; BINOM. Laboratory of knowledge, Moscow, p.295, 2008) 5. F.T. Bintam, M. Costa, I. “Eichenberger Some issues of metal ion toxicity,” M.: World, p.367, (1993) 6. N. Volovicheva, A. Vezentsev, S. Korolkova, P. Sokolovskiy, International Journal of Applied Engineering Research,. 10, 3138–31388, (2015) No. of the area from which the sample was taken Metal cation content in dry matter, mg/kg Content of metal cations in natural substance, mg/kg4 Mass fraction of moisture, % Cu2+ Pb2+ Cu2+ Pb2+ Control (without sorbent) 7.30 0.55 5.418 0.408 25.78 2 6.60 0.40 4.733 0.289 27.68 3 5.75 0.35 3.996 0.243 30.50 4 6.85 0.40 5.450 0.301 24.83 5 6.40 0.45 4.806 0.338 24.90 6 6.95 0.45 5.027 0.313 30.48 7 6.95 0.40 4.477 0.389 18.53 8 4.20 0.45 3.023 0.368 28.03 9 2.45 0.40 2.029 0.331 17.18 10 4.60 0.40 3.571 0.310 22.38 6 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

7. T. Vengris, T. Vengris, R. Binkiene, A. Sveikauskaite, Appl. Clay Sci., 18, 183–190, (2001) 8. A.I. Vezentsev, M.A. Trubitsyn, A.A. Romanshchak, Mining magazine, 1, 51–52. (2004) 9. A.I. Vezentsev, S.V. Korolkova, N.A. Volovicheva, Sorption and chromatographic processes, 5, pp. 790–795, (2008) 10. A.I Vezentsev, S.V. Korolkova, V.D. Bukhanov, Scientific statements of Belgorod State University. Series Natural Sciences, 9, pp. 119–123, (2010) 11. A.I. Vezentsev, M.A. Trubitsyn, L.F. GoldovskayaPeristaya, N.A. Volovicheva, Scientific statements of Belgorod State University. Series Natural Sciences, 3, 172–175, (2008) 12. R.E. Grim, Applied clay mineralogy (.McGraw-Hill, New York, p.422, 1962) 13. F. Bergaya, B.K.G.Theng, G. Lagaly, Hand book of clay science, (Elsevier, Netherlands p.1125, (2006) 14. Methodological guidelines for the definition of metals in farmland soils and crop production (TsINAO, Moscow: p. 61, 1992) 15. V.V. Milyutin, V.M. Gelis, GPKh. 67, 1776–1779, (1994) 16. Ed. J. Katz, G. Seaborg, L. Morss, “Chemistry of actinoids: In 3 vols.: Translated from English, (World, Moscow, 1, p. 525, 1991) 17. Ed. J. Katz, G. Seaborg, L. Morss, “Chemistry of actinoids: In 3 vols.: Translated from English, (World, Moscow, 1, p. 647., 1999) 18. V.V. Kovalsky, “Geochemical ecology, ( Science, Moscow, p.150, 1974) 19. MPC of chemicals in soil. Hygienic standards. No. 2.1.7.2041-06. 20. Chemist's Handbook. Volume 1/Under. Reduction of B.P. Nikolsky, p. 382. 21. M. Baghernejad, F. Javaher, A.A. Moosavi, Agronomy and Soil Science, 61, 1061–1077, (2015) 7 BIO Web of Conferences 30, 02001 (2021) https://doi.org/10.1051/bioconf/20213002001 ILS 2020

Сoordinating metal Mn2+ and Ni2+ compounds with acetylsalicylic acid: the influence on the cardiorespiratory system Elena Chuyan1 * , Marina Ravaeva1 , Igor Cheretaev1 , Irina Mironyuk1 , Svitlana Chornobay2 , Elena Birukova1 1 V.I. Vernadsky Crimean Federal University, 295007 Simferopol, Russia 2 Institute of Foreign Philology, V. I. Vernadsky Crimean Federal University, 295007 Simferopol, Russia Abstract. The paper researches the effect of manganese (АСMn2+) and nickel (АСNi2+) acetylsalicylates in doses of 5 and 10 mg/kg on the characteristics of the rats’ cardiorespiratory system. It is ascertained that coordinating metal compounds with the acetylsalicylic acid have a more pronounced biological effect in comparison with a monocompound of the acetylsalicylic acid; this makes the further search for coordinating compounds’ effects more promising. 1 Introduction A widespread problem of modern society is human pathologies connected with the functioning of different elements of cardiovascular system; this predetermines the necessity of searching for new effective substances and of studying their activity mechanism. The representatives of non-narcotic analgesics – the salicylates, namely the wellknown acetylsalicylic acid, can be a relatively safe remedy [1, 2]. Currently, the creation of new pharmaceutical dosage forms and remedies on the basis of the acetylsalicylic acid, being deprived its side effects, is an important area of the modern bioorganic and pharmaceutical chemistry and of biomedicine in general [3, 4]. The leading role in this area is played by new derivatives of the acetylsalicylic and salicylic acids, and by the compounds, obtained on their basis, with different biologically active molecules and metals [3], for instance, with Mn2+ and Ni2+. Such compounds are synthesized by the Department of General and Organic Chemistry of V. I. Vernadsky Crimean Federal University under the supervision of Professor A. N. Gusev; a range of these compounds’ chemical properties and some biological effects were studied [2]. However, the research of these compounds’ influence on the cardiorespiratory system has not been carried out yet. It is necessary to mention that important characteristics of the functional state of the whole cardiorespiratory system and the cardiac performance at a definite period of time and ones of the main oldest biomarkers of the body state on the whole are a heart rate (HR), a respiratory rate (RR), a systolic blood pressure (SBP) and a diastolic blood pressure (DBP). * Corresponding author: [email protected] 2 Experimental All the researches on the animals were carried out according to the principles set out in Directive 2010/63/EU of the European Parliament and of the EU Council of 22.09.2010 on the protection of animals used for scientific purposes. Healthy sexually mature male laboratory Wistar rats, weighing 180-200 gr (“FSUE “Nursery of laboratory animals “Rappolovo”) and having been placed under quarantine not less than for 14 days, were selected for the experiment. The experiments were performed on 70 male rats, characterized by an average motor activity and low emotionality in the “open field” test, and which make up the majority of the population; that is why they develop the most typical reaction to the effect of different factors [5], including the tested chemical compounds. The animals were kept under standard conditions of the vivarium at the temperature of 18–22оС on the bedding «Rexofix МК 2000» (on the basis of ear shanks) with the natural 12-hour day-and-night cycle, with free access to water (State Standard 33215-2014 «The handbook of keeping and nursing laboratory animals. The regulation rules on housing equipment and procedure organization»), and to full-fledged granulated food of State Standard Р-50258-92. The research was carried out at the Centre for Collective Use of Scientific Equipment “Experimental Physiology and Biophysics” of the Department of Human and Animal Physiology and Biophysics of V. I. Vernadsky Crimean Federal University. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02002 (2021) https://doi.org/10.1051/bioconf/20213002002 ILS 2020

Design of studies on the reaction of the cardiorespiratory system to the introduction of the tested compounds, the used research and statistical methods. The synthesis, the research of the composition, structure and properties of the coordinating compounds of the acetylsalicylates with nickel (АСNi2+) and manganese (АСMn2+) were done at the Department of General and Organic Chemistry of V. I. Vernadsky Crimean Federal University under the supervision of Professor A. N. Gusev. The research of the biological effect of the acetylsalicylic acid, АСNi2+ and АСMn2+ was carried out during their intraperitoneal injection into rats in the doses of 5 mg/kg and 10 mg/kg. For this purpose, the rats were divided into 7 groups (10 rats in each group): -group 1 is a biological control (К, n=10), they are the animals which were injected by the physiological solution of 0.9 % in the volume of 0.2 ml; -groups 2 – 3 are the animals which were injected by the acetylsalicylic acid in the doses of 5 mg/kg and 10 mg/kg respectively (n=10), the volume of 0.2 ml; -groups 4 – 5 are the animals which were injected by АСNi2+ in the doses of 5 mg/kg and 10 mg/kg respectively (n=10), the volume of 0.2 ml; -groups 6 – 7 are the animals which were injected by АСMn2+ in the doses of 5 mg/kg and 10 mg/kg respectively (n=10), the volume of 0.2 ml. The bioscreening of the acetylsalicylates was done 20 minutes later after the intraperitoneal injection in the stated concentrations, as at this period the maximum concentration of the acetylsalicylic acid is observed [6]. Simultaneously the following characteristics of all the groups’ animals were registered: heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). BP, HR and RR of the rats were registered with the help of the system NIBP200A («BiopacSystems, Inc.», USA). BP and HR were registered on the tail artery by applying the cuff on the tail base. In order to record RR the sensor was fixed on the chest area. While registering the indices, the animals were put into an individual box and were carried to the chamber Biopac with a constantly kept temperature of 330С for creation of comfortable conditions for the animal. The record of the indices was done during 5 minutes from the moment of the sensor’s signals stabilization. This time is enough for the five-fold BP measurement; HR and RR were being registered continuously. The record and the data processing were done by the computer with the help of the software program «AcqKnowledge 4.2 for MP150» (Fig. 1). The data of three repeated experiments were used for the statistical manipulation. The non-parametric statistic methods were applied as the distribution of variate values differed from the normal. The calculations, the statistical manipulation and graphic design of the obtained in the research data on the effect of the tested compounds on the physiological characteristics were done by using the program Microsoft Excel and the program package StatSoft STATISTICA 8. The reliability of the statistic differences between the control group (intraperitoneal injection of the physiological solution) and experimental groups with different doses of injecting the acetylsalicylic acid and acetylsalicylates Ni2+, Mn2+ was assessed by Mann-Whitney test. 3 Result and discussion It was found out that the animals of the control group, after being injected by the physiological solution, did not demonstrate reliable changes of the cardiorespiratory system characteristics (Table 1). At the same time the reliable lowering of HR by 12 % (р≤0.05) in animals, being injected by the acetylsalicylic acid in the dose of 5 mg/kg, was registered; however, at the increase of the injected dose up to 10 mg/kg the lowering of HR was less considerable – by 8% (р≤0.05). The reaction of the cardiorespiratory system to the introduction of the coordinating compounds АСNi2+ and АСMn2+ differed from the reaction to the introduction of the acetylsalicylic acid. The most pronounced changes of the cardiorespiratory system characteristics were observed in the rats being injected with АСMn2+. Thus, in contrast to the acetylsalicylic acid, the introduction of АСMn2+ in the dose of 5 mg/kg led to a reliable growth of HR by 5 % (р≤0.05). Besides, a reliable growth of DBP by 5 % (р≤0.05) and of RR by 15 % (р≤0.05) was observed as regards to the characteristics in the animal control group (see Table 1). The increase of the АСMn2+ dose up to 10 mg/kg led to the growth of HR by 7 % (р≤0.05), however, in contrast Fig. 1 The example of the recording of cardiovascular system indices of the rats’ BP, HR and RR under the effect of АСNi2+ in a dose of 5 mg/kg with the help of the software program «AcqKnowledge 4.2 for MP150» 2 BIO Web of Conferences 30, 02002 (2021) https://doi.org/10.1051/bioconf/20213002002 ILS 2020

to АСMn2+ in the dose, there was the lowering of RR by 14 % (р≤0.05) as regards to the characteristics in the animal control group. The rest of the characteristics did not change reliably (see Tables 1, Fig. 1). The increase of the АСMn2+ dose up to 10 mg/kg led to the growth of HR by 7 % (р≤0.05), however, in contrast to АСMn2+ in the dose, there was the lowering of RR by 14 % (р≤0.05) as regards to the characteristics in the animal control group. The rest of the characteristics did not change reliably (see Tables 1, Fig. 1). At the introduction of АСNi2+ in the dose of 5 mg/kg there was the lowering of RR by 15.1 % (р≤0.05) in comparison with the RR in the animal control group; with the increase of this compound dose up to 10 mg/kg the directivity of animals’ cardiorespiratory system reaction to the introduction of АСNi2+ remained identical to the same as at the introduction of 5 mg/kg dose: RR lowered by 14% (р≤0.05) in comparison with RR in the animal control group. The rest of the characteristics did not change reliably (see Tables 1, Fig. 1). Thus, the intraperitoneal introduction of the acetylsalicylic acid and acetylsalicylates Mn2+ and Ni2+ led to the changes of laboratory animals’ cardiorespiratory system functioning. The acetylsalicylic acid had a bradycardia effect in all the tested doses. The inclusion of the metal Ni2+ into the acetylsalicylic acid molecule structure led to the onset of bradypnoea but levelled the bradycardia effect. The inclusion of Mn2+ into the acetylsalicylic acid molecule had the most significant effect; it was evidenced in the stimulation of the cardiorespiratory system (in the dose of 5 mg/kg): DBP, HR and RR increased, however, at the dose of 10 mg/kg tachycardia enhanced insignificantly, and tachypnea was changed by bradypnoea. We may conclude that the acetylsalicylic acid molecule modification results in the changes of the effects of the initial compound and in the emergence of new characteristics Actually, the analysis of the coordinating compounds АСMn2+ and АСNi2+ efficiency regarding the acetylsalicylic acid showed (Fig. 2) that the maximum changes of the cardiorespiratory system indices were registered at the modification of the acetylsalicylic acid by metal Mn2+, as at the introduction of АСMn2+ in the dose of 5 mg/kg the animals increased reliably RR by 14.7% (р≤0.05) and DBP by 7.1 % (р≤0.05) as regards to the indices in the animal group which was injected by the acetylsalicylic acid in this dose. Table 1. The characteristics of the rats cardiorespiratory system after injecting the acetylsalicylic acid and acetylsalicylates of Ni 2+ and Mn 2+ in different concentrations Group SBP, mm m.c.. DBP, mm.m.c. HR, b./min RR, r.r./min Control (1) 113.4±1.32 72.20±0.91 378.4±15.23 109.67±4.38 The acetylsalicylic acid 5 mg/kg (2) 114.6±1.18 70.7±1.07 334.8±16.7 1≤0.05 109.9±3.59 10mg/kg (3) 112±1.18 70.07±0.94 347.63±6.3 p1≤0.05 106.8±4.38 АСMn2+ 5mg/kg (4) 114.60±1.94 75.73±1.25 р1≤0.05 p2≤0.05 396.13±11.85 p1≤0.05 126.07±8.26 p1≤0.05 p2≤0.05 p5≤0.05 p6≤0.05 10mg/kg (5) 112.40±2.08 75.07±0.79 p2≤0.05 406.73±9.86 p1≤0.05 p2≤0.05 p7≤0.05 94.53±1.79 p1≤0.05 p2≤0.05 p4≤0.05 p7≤0.05 АСNi2+ 5 mg/kg (6) 113.73±1.95 73.53±1.07 p2 ≤0.05 412.87±16.56 p7≤0.05 93.13±2.71 p1≤0.05 p4≤0.05 p7≤0.05 10mg/kg (7) 111.20±2.09 75.67±1.08 p2≤0.05 333.13±12.89 p5≤0.05 p6≤0.05 81.00±2.16 p1≤0.05 p2≤0.05 p5≤0.05 p6≤0.05 Note: М is an average arithmetic value, М±m is an error of mean, р 1-7 is the confidence level of indices difference according to Mann-Whitney test concerning the corresponding animal groups; SBP is a systolic blood pressure; DBP is a diastolic blood pressure; HR is heart rate; RR is a respiratory rate 3 BIO Web of Conferences 30, 02002 (2021) https://doi.org/10.1051/bioconf/20213002002 ILS 2020

Fig 2. The characteristics of the cardiorespiratory systems of animals, injected by the acetylsalicylic acid and acetylsalicylates of Mn2+and Ni2+ in concentrations of 5 mg/kg and 10 mg/kg relatively to the values in the group of animals, injected by the acetylsalicylic acid, and taken as 100 %. Note: * is the confidence level of differences according to MannWhitney test relatively to the values of the indices in control; SBP is a systolic blood pressure; DBP is a diastolic blood pressure; HR is heart rate; RR is a respiratory rate. At the introduction of АСNi2+ in the dose of 5 mg/kg only DBP increased reliably by 4 % (р≤0.05) as regards to the indices in the animal group which was injected by the acetylsalicylic acid. The rest of the cardiorespiratory system characteristics in the animal groups 4 – 7 regarding the group of animals injected by the acetylsalicylic acid were not observed. 4 Conclusion On the whole, the results of this research allowed ascertaining that the acetylsalicylic acid complexing with such metals as nickel and manganese improve the efficiency of newly synthesized acetylsalicylates since АСNi2+ and АСMn2+ have a more pronounced effect on the cardiorespiratory system of the animals in comparison with the acetylsalicylic acid. The manifestation of the more pronounced effects of metal acetylsalicylates in comparison with the acetylsalicylic acid is presented in the researches of Z. Chohan and coauthors on the kaolin model of the rats’ inflammation, and in the modelling of the rats’ acute myocardial infarction [7]. Our researches show that the compounds АСNi2+ and АСMn2+ demonstrate some new properties which are not typical of the acetylsalicylic acid. Probably, the obtained in this research effects of the acetylsalicylic acid with transition metals Ni2+ and Mn2+ may be connected with their ability to interact with metalloenzymes, as it is shown in [7], and/or with their ability to change the activity of a number including arginase, of enzymes [8,9,10], superoxide dismutase-1, glutathione peroxidase4, NA+/K+-ATPase [11], and, thus, to inhibit proinflammatory prostanoids and intensify the activity of antioxidant enzymes [11]. Thus, the acetylsalicylates of nickel and manganese show biological properties which can be of a specific interest in the process of treating a number of cardiorespiratory system diseases; this makes the further search for biological and pharmaceutical activity of these coordinating compounds promising. Since the compounds АСNi2+ and АСMn2+ have qualitatively and quantitatively effects different from such of the acetylsalicylic acid, then the further research of the salicylic acid derivatives can solve the problem of the side effects, increase the therapeutic potential of the initial compound for the creation of new effective compounds on their basis. Acknowledgment The reported study was funded by RFBR, project number № 20-33-70142 on the experimental equipment of the Center for Collective Use of Scientific Equipment "Experimental Physiology and Biophysics" of the Department of Human and Animal Physiology and Biophysics of Taurida Academy (structural division) of V. I. Vernadsky Crimean Federal University References 1. A.G. Gilman, Practice, 4, p.336 (2006) 2. I. V. Cheretaev, D. R. Khusainov., I. I. Koreniuk, Young Scientist, 10, 485-491, (2015) 3. A. S. Grigorieva, Trace elements in medicine, 1, 17-22, 2000. 4. K. Bica, C. Rijksen, M. Nieuwenhuyzena [et al.], Phys. Chem, 12, 2011-2017 (2010) 5. I V. Cheretaev, M. Yu. Ravaeva, E. R Dzheldubaeva, E. N. Chuyan, V. F. Shulgin, N. Sheichmambetov, M.V. Palaevskaya, Scientific notes of the Crimean Federal University named after V.I. Vernadsky. Biology, Chemistry, 5, 204-206 (2019) 4 BIO Web of Conferences 30, 02002 (2021) https://doi.org/10.1051/bioconf/20213002002 ILS 2020

Tea Antioxidants Ludmila Deineka 1* , Aigerim Zhakiyanova2 , Yenglik Amrenova2 and Irina Blinova1 1Belgorod State National Research University, Department of Chemistry, 308015 Belgorod, Russia 2Al-Farabi Kazakh National University, Department of chemistry and chemical technology, 050040 Almaty, Kazakhstan Abstract.. In thе paper, antioxidant activity (AOA) of tea infusions as a function of infusion time and type or brand of teas as well as a concentration of caffeine were measured. The main components of green tea infusions are identified as epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and caffeine. It has been shown that the antioxidant activity depends on the time of infusion and the degree of tea grinding. while there is a linear dependence between AOA and concentration of caffeine in tea. Thus the only method to reduce content of caffeine in the infusion is a preliminary withdrawal of caffeine from the plant material 1 Introduction Tea began to be used in China 4-5 thousand years ago as a medicine. Tea leaves were ground with rice and made into flat cakes. Until now, in some countries, tea was consumed as a food in the form of a salad or soup cooked from tea leaves. The first book about tea as a drink appeared in the VIII century. It was written by LU Yu and was called "the Canon of tea". In Russia, tea appeared for the first time during the reign of Ivan III. Tea is currently the most popular drink in the world. In Uzbekistan, tea lovers are 99.6% of the population, in Azerbaijan-99.1%, in China-98.9% and in Egypt98.5%. In Russia, 77.5% of residents prefer to drink tea, and 22.5%— coffee. The range of teas grown and produced by the industry is very large, but among the variety there are main types of tea: black (fully fermented), Oolong (partially fermented) and green (unfermented). In recent years, new types of tea have appeared on the world market: white, yellow, PU-erh and others [1, 2]. Currently, tea is consumed by more than 4 billion people, as, in addition to taste, the health benefits of tea are not in doubt. Tea contains a large number of compounds that are strong antioxidants. These are primarily catechins, which are present in large quantities, especially in green tea. Green tea catechins and black tea theaflavins prevent and suppress cancer [3]. Consumption of 250-500 ml of tea per day reduces mortality from ischemic disease by 2 times [4]. the inverse relationship between tea consumption and cholesterol levels is shown. [5]. The antioxidant effect of tea on the human body has been shown [6], antibacterial [7], antimicrobial [8], antiviral [9], and antidiabetic [10]. Catechins are the most useful components of tea, making a great contribution to the antioxidant activity of * Corresponding author: [email protected] the drink. The main catechins of tea are eight, but 70% are epigallocatechin gallate (EGCG) and epigallocatechin (ECG). The total content of catechins are: in green tea from 130 to 220 mg/g, in Oolong tea on average 65 mg/g, and in black tea about 5 mg / g [1]. Tea helps to increase performance and attention due to the presence of caffeine - an alkaloid with a bitter taste that excitingly affects the body. According to literature data, the content of caffeine in green tea and Oolong tea varies from 26 to 40 mg/g, and in black teas, the content of caffeine is 15- 33 mg/g, [1]. The purpose of this work is to study the influence of types and brands of teas, methods of sample preparation and conditions of infusion on the most important characteristics that determine the benefits of using tea. 2 Experimental 2.1 Sample preparation Samples of tea or tea drinks were weighed on analytical scales at 1.0 gram and filled with 50.0 or 100 ml of boiling distilled water. Stirred and allowed to infuse for a certain time, filtered first through a paper filter, then through a syringe filter. A sample was taken from the resulting extract for HPLC analysis. The method of high-performance liquid chromatography (HPLC) was used to determine catechins and caffeine in tea and tea drinks. The analysis was performed using an Agilent Infinity 1200 chromatograph with a diode array detector. The volume of the analyzed sample (10 L) and the flow rate of the mobile phase (0.8 mL/min) were set. Caffeine and catechins were separated on the Repsosil-Pur C18-AQ © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02003 (2021) https://doi.org/10.1051/bioconf/20213002003 ILS 2020

column (1004,6 mm, particle size 3 m) and detected by absorption at a wavelength of 273nm. A calibration graph was constructed for the quantitative determination of caffeine. For determination of antioxidant activity was used the spectrophotometric Folin-Ciocalteu method 2.2 Preparation of reagents A solution of sodium carbonate was prepared by dissolving (10.00±0.01) g of Na2CO3 in distilled water in a 100 cm3 flask and brought to the mark. (0.0433±0.0001) g gallic acid monohydrate (0.002547059 mmol) was placed in a 100 cm3 volumetric flask, dissolved in distilled water, and brought to the mark. To build a calibration line, a series of solutions were prepared: 1.0 cm3 of 10% Na2CO3 was mixed in 5 ml flasks with 0.03; 0.05; 0.07 or 0.015 ml of gallic acid solution were added. Using a pipette dispenser, 0.2 ml of Folin-Chocalteu reagent was added to each flask, mixed, and brought to the mark with water. The solutions are kept for 30 minutes at room temperature, and the optical density of the solutions relative to water was measured at a wavelength of 760 nm (Fig.1). Fig.1 The calibration plot for gallic acid as a reference solute The relationship between the amount of Gallic acid introduced (n, mmol) and the intensity (A) of the color is linear: А = 0,4303 · n + 0, 0035. (R2 =0,9968) 3 Results and discussion Tea has a complex chemical composition; it contains more than 2000 compounds. But it is very important to establish the dependence of the quality of tea on its composition and to establish the influence of individual tea compounds on human health in order to investigate the possibility of using tea for antioxidant therapy. First of all, it is necessary to distinguish catechins, the main catechins of tea: epigallocatechin gallate (EGCG) and epigallocatechin (EGCG). Green teas are most rich in catechins. The total content of catechins decreases significantly with the degree of fermentation. When tea is fermented to 85%, the total content of catechins can be reduced by 10 times or more, since catechins are converted to theaflavins, Accordingly, black fermented tea contains a large amount of theaflavins and products of condensation and polymerization of catechins (Fig.2.). At the same time, the caffeine is still preserved Fig.2 Structures of epigallocatechingallate (EGCG, I) and theaflavin-1 (II). These compounds are antioxidants that largely determine the antioxidant activity of tea, and therefore being usefulness. Therefore, it is very important to choose the optimal tea varieties and methods of infusion to achieve maximum antioxidant activity. The main catechins (epigallocatechin gallate and epicatechingallate) and caffeine were determined by reverse-phase high-performance liquid chromatography (RP-HPLC). The chromatogram of green tea extract is shown in Fig. 3., where the presence of three main components is obvious. Fig 3. Green tea extract chromatogram: A-extraction by eluent, B - extraction by infusing in hot water.1- epigallocatechingallate (EGCG), 2-caffeine, 3- epicatechingallate (ECG) Extraction was performed with two extractants: an eluent for HPLC determination and an infusion in hot water. The eluent extraction was performed to control the completeness of extraction of tea components when infused in hot water. Catechins are substances that are unstable to oxidation, but the use of an extraction technique that involves infusing a sample of tea in hot water is necessary to assess the actual extractability of catechins when drinking tea using the traditional method of infusion. Table 1 shows data from a 2015 beverage study on the content of catechins and caffeine in various teas. Experimental data show that hot water can be used to extract catechins and caffeine. The highest content of catechins when brewed for 5 minutes was found for green tea "Akbar Gold "and White tea "Ice dragon". At 2 BIO Web of Conferences 30, 02003 (2021) https://doi.org/10.1051/bioconf/20213002003 ILS 2020

the same time, the highest concentration of caffeine was found in the drink made of tea "Akbar Gold". In a series of studies performed in 2020, we compared the dependence of the extraction of caffeine in the drink depending on the time of tea brewing, Fig.4. Table 1. Concentration of catechins and caffeine in the drink when brewed for 5 minutes, mg/g (n= 3) № Name and type of tea Catechins Caffeine 1 Green tea «Curtis» 180 ± 6 26,1 ± 0.1 2 Green tea «Real Ceylon» 178 ± 6 22,9 ± 0.1 3 Green tea «Akbar Gold» 223 ± 7 28,9 ± 0.1 4 White tea « Ice dragon » 205 ± 6 24,9 ± 0.1 5 Green tea « Java» 191 ± 6 28,1 ± 0.1 6 Green tea «Imah Moroccan mint» 95 ± 5 18,0 ± 0.1 Fig. 4. The content of caffeine in different tea samples depending on the time of tea brewing. Increasing the brewing time from 5 to 60 min. practically does not affect the degree of extraction of caffeine in tea. In a special brand of decaffeinated tea "Milford", caffeine was not found, which cofirms the effectiveness of the supercritical CO2 extraction used in the manufacture of the product. Fig. 5 shows data on the content of caffeine in drinks made from different varieties and types of tea. Fig.5. The caffeine content of different brands of tea when brewed for 5 minutes, (n= 3). To determine the effect of tea brewing time on the amount of antioxidant activity of tea and the content of caffeine in it, black ground tea Grienfield Glassic Breakfast and green ground tea Richard Royal Green Tea were selected. The brewing time was selected in minutes: 1, 2, 4, 5, 17, 19. Fig. 6-7 shows the results obtained for Greenfield Classic Breakfast black ground tea. From experimental data, it can be seen that both the content of caffeine and even more antioxidant activity increase with an increase in the brewing time of black tea to 19 minutes. But we have found that further increase of extraction time leads to an increase of the caffeine concentration as well as to increased antioxidant activity though after 2 hours of infussion a decrease in antioxidant activity of the beverage by 12% was found. Thus we can conclude that to achieve the maximum value of the antioxidant activity of tea, it is necessary to maintain the drink during brewing for up to 20 minutes. Fig.6. Influence of brewing time of Greenfield Classic Breakfast black ground tea on caffeine content and antioxidant activity brewing Time (min.): 1 - 1; 2 - 2; 3 - 4.; 4 - 5; 5 - 17; 6 - 19. Fig.7. Correlation between caffeine content in Greenfield Classic Breakfast black ground tea on the antioxidant activity of tea Fig. 8-9 shows the results on the effect of brewing time of Richard Royal Green Tea on the caffeine content and antioxidant activity. The caffeine content and antioxidant activity of green tea increase with increasing brewing time only up to a certain time (5 min), and then decrease. Therefore, in order to achieve maximum antioxidant activity when brewing green tea, it is necessary to maintain the drink during brewing for up to 5 minutes 3 BIO Web of Conferences 30, 02003 (2021) https://doi.org/10.1051/bioconf/20213002003 ILS 2020

Fig.8. Influence of brewing time of Richard Royal Green Tea on the caffeine content and antioxidant activity. Brewing time (min.): 1 - 1; 2 - 2; 3 - 4.; 4 - 5; 5 - 17; 6 - 19. Fig.9. Influence of the growth of caffeine content in Richard Royal green tea on the antioxidant activity of tea. Fig. 7 and 9 show that both black tea and green tea show a directly proportional relationship between an increase in antioxidant activity and an increase in their caffeine content. To find out the influence of the degree of grinding of dried tea leaves on the amount of antioxidant activity, identical samples of leaves of different types of tea were brewed in the state of the leaf and after grinding. The antioxidant activity of 6 samples of green tea and two samples of black tea and tea drink were determined depending on the degree of grinding of vegetable raw materials, Table 2. Finely crushed tea allows to get when brewing at the same conditions an infusion being 1.5-3.0 times higher by antioxidant activity than non-ground tea. And only for the roiboos drink, the antioxidant activity does not depend on the degree of grinding of the dried raw material. It is no accident that powdered raw materials are used for brewing tea ceremonies. 4 Conclusion Hot water can be used to completely extract caffeine and catechins from tea. The content of caffeine and antioxidant activity increases with increasing brewing of black tea up to 20 minutes, green tea - up to 5 minutes, then the antioxidant activity decreases. The antioxidant activity of crushed tea is 1.5-3 times greater than non-crushed tea. Table 2. Antioxidant Activity Of Some Teas And Tea Beverages (As Gallic Acid Equvalent) (n=3). № Name of tea Manufacturer crushed noncrushed 1 Tan Cuong green tea Vietnam 207 ± 7 135 ± 4 2 green tea Yunnan China 295 ± 8 125 ± 4 3 Green Jasmine tea China 255 ± 7 99 ± 3 4 Maitre de The Napoleon France 201 ± 7 65 ± 3 5 Ahmad Tea Bluebberry Russia 210 ± 7 96 ± 5 6 Hyleys Green Tea Sri Lanka 258 ± 9 127 ± 5 7 Grienfield Сlassic Breakfast black tea London 155 ± 6 89 ± 4 8 Welsrhous, black tea Nepal 136 ± 6 75 ± 3 9 Grienfield Herbal Tea Creamy Roiboos London 67 ± 4 62 ± 4 References 1. Ya. I. Yashin, A. Ya. Yashin, Tea. Chemical composition of tea and its influence on human health, (Translit, Moscow, 2010). 2. Ya. I. Yashin, V. Yu. Ryisnev, A. Ya. Yashin, N. I. Chernousov, “Natural antioxidant. The content in food products and the impact on human health and aging”, (Translit, Moscow, 2009). 3. H. Fujiki e.a., Mutat. Rec., 402, 307-310 (1998) 4. M.G. Hertog et al., Lancet, 342, 1007-1011, (1993) 5. I. Stensvold, A. Tverdal, K.Soivoll, O.P.Foss, Prev. Med., 21, 546-553 (1992) 6. A. Rietveld, S Wiseman, J. Nutr., 133, 3285S3292S (2003) 7. Y. Yamamoto et al, Biofactors, 21, 119-121 (2004) 8. I. Kubo, H. Muroi, M. Himejima, J. Agric. Food Chem., 40, 245-248, (1992) 9. G. Fassina et al., AIDS, 16, 939-941 (2002) 10. E. Polychronopoulos, A. Zeimekis, C.M. Kastorini et al, Eur. J. Nutr., 47, 10-16 (2008) 4 BIO Web of Conferences 30, 02003 (2021) https://doi.org/10.1051/bioconf/20213002003 ILS 2020

Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures Aleksandr Dudoladov1* , Marina Alekhina1 , Aleksandra Revina2 , and Olga Souvorova2 1 Mendeleev University of Chemical Technology of Russia, Moscow, Russia 2 Institute of Physical Chemistry and Electrochemistry of RAS, Moscow, Russia Abstract. On the basis of granular synthetic zeolites NaY, HY, and ZSM-5, adsorbents containing nanoparticles of silver, cobalt, molybdenum, and tungsten were obtained. The samples have a lower surface polarity in comparison with the initial zeolites, which is reflected in the selectivity of a number of samples with respect to argon. This is due to the fact that the argon molecule interacts with zeolites only through nonspecific forces. Modification was performed by interacting with reverse-micellar solutions of nanoparticles. The actual sizes of metal particles and their distribution over the surface of the modified samples of zeolites have been determined by the method of transmission electron microscopy. The samples’ equilibrium adsorption capacities for oxygen and argon (25°С and atmospheric pressure) and the separation coefficient of the argon–oxygen mixture as the ratio of Henry’s coefficients have been determined. It has been demonstrated that samples of the NaY zeolite modified with silver nanoparticles have the separation coefficient value of the argon–oxygen gas mixture equal to 1.6. 1 Introduction Zeolites are widely used in industry for the separation of various gas mixtures, in particular for air separation by the PSA method [1-5]. Modifying the surface of high-silicon zeolites of Y and ZSM types by introducing metal nanoparticles (NPs) is one of the promising directions for creating nanocomposite materials with specified properties for gas purification and separation due to the unique properties of NPs. The presence of transition metals on the surface of materials changes their adsorption and catalytic properties. Nanocomposites based on γ-Al2O3 with Au or Ru NPs adsorbed on the surface [6] have high catalytic activity in the reaction of hydrogen isotope exchange. An effective ethanol oxidation catalyst was obtained on the basis of Pd and Ag nanotubes deposited on carbon nanotubes [7]. Modification of the silica surface by metal nanoparticles reduces the polarity of these adsorbents. As shown in [8,9], the contributions of specific interactions of polar compounds on silicas containing NPs metals are less than on the initial one. The authors explain this fact by shielding the active centers of the silica gel surface with metal nanoparticles. Zeolite matrices have a great potential as carriers of transition metals, since they allow to stabilize nanoparticles of certain sizes, in particular metal clusters, without the use of additional stabilizers. In [10-13], the UV spectroscopy method shows high stability of NPs and silver clusters for all the studied types of zeolite matrices, which is expressed in the invariance of the position and intensity of the corresponding absorption bands. * Corresponding author: [email protected] Differences in the surface acidity of the studied zeolite matrices did not affect the stability of the NPs in their structures. The study of catalytic activity of zeolites with different concentrations of the silver NPs [10-13] showed that the optimum content of NPS for carrying out oxidation reactions of H2 and CO is 5-10 wt. %. Great attention is paid to selection of the synthesis method of NPs metals [14-18], because the method of preparation and the conditions of synthesis of nanoparticles depend on their properties such as size, shape, stability of the particles in time, the possibility of their application to different media, and as a result, adsorption and catalytic properties. In this work were used nanoparticles obtained by synthesizing stable NPs in reverse micelles with characteristic optical absorption spectra and a high ability for adsorption on various substrates [19,20]. At the Frumkin Institute of physical chemistry and electrochemistry of the Russian Academy of Sciences has developed a method for. It belongs to a group of chemical methods in which NPs are obtained by chemical or radiation-chemical reduction of metal ions from their salts to atoms under conditions conducive to the subsequent formation of nanosized metal particles. NPs deposition on the surface of the carrier can be carried out directly from the reverse micellar solution, that is, the medium of their synthesis, which greatly simplifies the process of obtaining nanocomposites. The small size © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02004 (2021) https://doi.org/10.1051/bioconf/20213002004 ILS 2020

of metal particles in zeolite, according to the authors [13], is due to nanoscale pores in the zeolite framework, which allow to control the particles size and have a uniform distribution of metal on the internal and external surfaces of the adsorbent. According to IR spectroscopy data, modification of zeolites by transition metal does not lead to a significant change in the degree of crystallinity of high-silicon zeolites [21,22]. The aim of this work was to modify zeolites of types Y and ZSM-5 with transition metal nanoparticles to change the surface polarity of these adsorbents, which was detected by adsorption of air macro-components on the obtained zeolite samples. 2 Experimental In this work, studies were carried out to modify samples of zeolites of types Y and ZSM-5 by interacting with a suspension of metal nanoparticles (Ag, Co, Mo, W and mixed Mo-W) in produced reverse micellar solution (herein after referred to as RMS). In the experiment we used granulated zeolites NaY and HY without binding agents and ZSM-5 in H-form with a binder (molar ratio SiO2/Al2O3 ~ 30), provided to us by the Institute of petrochemistry and catalysis of the Russian Academy of Sciences. For research, were used a zeolite fraction with a particle size of 1-2 mm. Reverse micellar solutions were prepared according to the method given in [8,19,20]. in 0.15 M surfactant solution, which was used as AOT (bis(2-ethylhexyl) sodium sulfosuccinate), the necessary amount of an aqueous solution of 0.3 M AgNO3 (or the corresponding salt) was added in isooctane. The value of the degree of hydration, equal to the molar ratio of water and AOT in the reverse micellar solution, was 5.0. In addition, a polyphenolic compound flavonoid–quercetin (3,5,7,3’, 4’- pentahydroxyflavone) was added as a ion redactant in a 0.15 M solution of AOT/isooctane. RMS NPs was added to pre-calcined at 350 °C type Y or ZSM-5 zeolite with a particle size of 1-2 mm. The volume ratio of the components zeolite/ RMS of NPs Me/isooctane (medium) was 1:1:1. The zeolite was kept in solution for several days. The resulting sample was separated on a blue ribbon filter and dried at room temperature. The content of metal NPs in the solution during interaction with zeolite was controlled using a spectrophotometer SF-2000 (OKB SPEKTR, Russia). For measurement quartz cuvettes with a cross section of 1x1 cm were used. Samples of the solution for analysis were taken 15 min after adding RMS to the zeolite weighed portion, then every 10-15 min, then 30 min, then a day after the start of the experiment, followed by washing with isooctane and ethanol. The elemental composition of the samples was determined by x-ray fluorescence using the x-MAX INCA ENERGY attachment (Oxford Instruments, UK) to the JEOL JSM-6510 LV electron microscope (JEOL, Japan) at the Mendeleev Center of Collective Use. The structural and energy characteristics of adsorbents were determined using nitrogen adsorption isotherms at 77 K, taken at the Nova 1200E volumetric unit (Quantachrome, USA). Before measuring the isotherms, the samples were degassed at 400°C and at residual pressure of 10-3 mm Hg for 4 hours. The specific surface area (Ssp) of the samples was calculated using the BET equation, the volume of micropores (W0) and the characteristic adsorption energy (E0) were calculated using the Dubinin – Astakhov equation. The total sorption volume of meso-and micropores (Vs) was determined from the nitrogen adsorption isotherm at a relative pressure value of 0.995. The microstructure of the obtained samples was analyzed using transmission electron microscopy (TEM) using a LEO 912 AB Omega ("Carl Zeiss") microscope. The microscope is equipped with an integrated OMEGA energy filter (Zeiss), as well as a digital camera SIS/Olympus Omega 2K. Acceleration voltage of the microscope: 100 kV, image resolution: 0.2-0.34 nm. Sample preparation consisted of grinding the obtained samples in an agate mortar followed by ultrasonic dispersion in ethanol, then the samples were applied to copper grids and dried in air. Nitrogen, oxygen and argon from cylinders were used as adsorbents. Helium was used as the calibration gas. Nitrogen, oxygen, argon and helium were produced in the Kurchatov Institute and had a purity of: nitrogen − 99.999 vol. % N2; oxygen − 99.999 vol. % O2; helium − 99.995 vol. % He and argon − 99.993 vol.% Ar. The values of the equilibrium adsorption capacity of samples for nitrogen, oxygen and argon were determined on the basis of kinetic curves of the adsorption of these gases at 250C and atmospheric pressure, taken on a volumetric unit. The relative measurement error was no more than 5%. As a measure of the adsorption selectivity of the samples, we used the separation coefficient (Ks), which was calculated as the ratio of Henry's coefficients at atmospheric pressure and 250C. It is known that the isotherms of individual adsorption of air macrocomponents on zeolites at room temperature in the range of operating pressures in adsorption oxygen generators are linear, so the adsorption of each of them is considered independent of the adsorption of other components present [23]. 3 Results and discussion The change in the concentration of transition metals in solutions during adsorption and washing with solvents were controlled by the intensity of optical absorption spectra. The optical absorption spectra of RMS silver NPs in presence of NaY zeolite are shown in Fig. 1. In all experiments, we observed a decrease in the intensity of the optical absorption peak of silver nanoparticles over time, which indicates the transition of NPs metals from the solution to the surface of zeolites. Fig. 1 also shows that a day after the zeolites were immersed in the reverse micellar solution, the value of optical density (~410 nm) of the absorption band of Ag nanoparticles decreased to a minimum value, which may indicate the adsorption of nanoparticles on zeolites and that the nanoparticles are not washed out with solvents. We observed the similar pictures during the adsorption of NPs 2 BIO Web of Conferences 30, 02004 (2021) https://doi.org/10.1051/bioconf/20213002004 ILS 2020

of all other studied metals from RMS on NaY, HY and ZSM-5 zeolites Fig. 1. Optical absorption Spectra of RMS NPs Ag when adsorbed on NaY zeolite: 1-the initial solution of RMS NCH Ag, 2-the 1st sample, 3-the 2nd sample, 4-the 3rd sample, 5-the 4th sample, 6-a day later, 7-the sample after washing with isooctane, 8-the sample after washing with ethanol. According to the results of elemental analysis, the content of transition metals in the modified samples was low, in the range of 0.3-0.4 wt.%. In table 1, the content of Ag and Co in wt. % is shown in the first column next to the designation of the zeolite sample. Fig. 2 shows electronic photographs of the Ag / NaY zeolite surface after the interaction of NaY zeolite with NPs Ag RMS. It can be concluded that there is a uniform distribution of particles on the surface of the zeolite with a particle size of 1-3 nm. Figures 3,4 shows the isotherms of nitrogen adsorption at 77 K on the initial zeolites of types Y and ZSM-5, and zeolites modified with metal NPs. As can be seen from Fig. 3, the nitrogen adsorption isotherms at 77 K on the original NaY zeolite and the Ag/NaY sample are almost identical, for other Mo/NaY, W/NaY and Mo-W/NaY samples, the isotherms are located higher. Nitrogen adsorption on HY in the initial region of the isotherm was significantly higher than on the Ag/HY sample, which indicates that active nitrogen sorption centers were blocked on the modified sample. The structural and energy characteristics of zeolites calculated on the basis of experimental adsorption isotherms are shown in table 1 All samples modified with NPs metals are characterized by a decrease in the values of the characteristic adsorption energy (E0) in comparison with the original zeolites. Fig.2. Micrographs of the Ag/NaY sample surface. Fig. 3. Isotherms of nitrogen adsorption at 77 K on zeolites NaY and HY: 1 – NaY, 2 – Ag/NaY, 3– Mo/NaY, 4 – W/NaY, 5 – Mo-W/NaY, 6 – HY, 7 – Ag/HY. Table 1. Structural and energy characteristics of Y and ZSM-5 zeolites. c Ssp (BET), m2 /g E0, kJ/mol W0, cm3 /g Vs, cm3 /g Vs-W0, cm3 /g NaY 506 40.5 0.28 0.31 0.03 Ag/NaY (0.4) 519 39.0 0.28 0.31 0.03 Mo/NaY 519 37.7 0.28 0.32 0.04 W/NaY 570 37.0 0.28 0.35 0.07 Mo-W/NaY 560 37.7 0.30 0.34 0.04 HY 467 30.0 0.25 0.31 0.06 Ag/HY (0.3) 432 24.9 0.22 0.31 0.09 ZSM-5 267 24.1 0.13 0,40 0.27 Ag/ZSM-5 (0.4) 264 22.3 0.13 0.37 0.24 Co/ZSM-5 (0.4) 254 21.7 0.12 0.33 0.21 3 BIO Web of Conferences 30, 02004 (2021) https://doi.org/10.1051/bioconf/20213002004 ILS 2020

For all modified NaY zeolite samples, an increase in Ssp was observed compared to the original NaY. The volumes of micropores (Wo) remained almost unchanged, except for the Mo-W/NaY sample; an increase in Vs values was observed for samples containing tungsten and molybdenum nanoparticles and a mixture of Mo-W nanoparticles. Apparently, metal nanoparticles are located on the outer surface of NaY zeolite particles and in transport pores, which contributed to the creation of an additional volume of sorbing pores and an increasing in the specific surface area. Fig. 4. Isotherms of nitrogen adsorption at 77 K on zeolites ZSM-5: 1 – Ag/ZSM-5, 2 – Co/ZSM-5, 3 – ZSM-5. For HY and ZSM-5 zeolites, there was a slight decrease in Ssp values compared to the original samples. In the case of Ag/HY, there was a decrease in the volume of micropores compared to the original HY while maintaining the Vs value. It follows that the silver nanoparticles were located in the transport pores, while partially blocking the entrance windows to the micropores. A similar conclusion can be drawn about the location of silver and cobalt nanoparticles in samples of zeolites Ag/ZSM-5 and Co/ZSM-5. The effect of modification of zeolites with metal nanoparticles was investigated by adsorption of air macro-components on the obtained samples. Nitrogen, oxygen, and argon have similar properties. The differences are that nitrogen and oxygen have quadrupole moments, and nitrogen has a quadrupole moment value three times greater than oxygen. Nitrogen and oxygen molecules interact with the surface of adsorbents due to non-specific forces and specific forces (ion-quadrupole interaction). Argon is a molecule with a spherically symmetrical electron shell that interacts with the surface of adsorbents only due to non-specific forces, mainly dispersion attraction. On the basis of kinetic curves, the equilibrium capacities of adsorbents for nitrogen, oxygen and argon were determined, which are presented in table 2. According to the table 2, the sample of zeolite Ag/NaY had the highest selectivity to argon. The separation coefficient of the argon-oxygen mixture was 1.6. In this case, the adsorption of nitrogen and oxygen on the Ag/NaY sample was approximately the same, in contrast to the initial NaY, on which nitrogen was adsorbed better. The use of Mo, W nanoparticles and their mixtures as modifiers did not change the nitrogen adsorption on the Mo/NaY, W/NaY and Mo-W/NaY samples in relation to NaY and simultaneously led to an increase in the adsorption of O2 and Ar by 1.5-2 times. For these samples, the selectivity to argon was minimal. The value of the separation coefficient of the argonoxygen mixture The HY zeolite was characterized by practically the same adsorption of all gases. After modification with Ag NPs, nitrogen adsorption on Ag/HY decreased by half. Sample Ag/HY had some selectivity with respect to oxygen (the Ks of the O2-N2 mixture was 1.8); for this sample, a slight excess of the adsorption of argon over oxygen was also recorded (the Ks of the Ar-O2 mixture was 1.2). On ZSM-5 zeolite after modification with Ag and Co nanoparticles observed an increase in the values of the equilibrium capacity for oxygen and argon by about 2 times, while the selectivity to argon was low (Ks = 1.1-1.3). for these samples was 1.2-1.3. Table 2. Equilibrium capacitirs of zeolites fpr nitrogen, oxygen, and argon and separation coefficient for N2 – O2 and AR – O2 mixtures. Zeolite Equilibrium adsorption at 25°С and 0.1 MPa, cm3 /g Ks N2 O2 Ar N2–O2 Ar–O2 NaY 4.7 3.8 3.5 1.3 - Ag/NaY (0.4) 1.7 1.6 2.6 1.0 1.6 Mo/NaY 4.4 5.4 6.5 - 1.2 W/NaY 4.5 5.3 5.3 - 1.0 Mo-W/NaY 4.7 5.3 6.9 - 1.3 HY 2.8 3.0 3.0 - 1.0 Ag/HY (0.3) 1.4 2.5 3.0 - 1.2 ZSM-5 4.5 4.3 3.8 1.0 - Ag/ZSM-5 (0.4) - 7.2 8.1 - 1.1 Co/ZSM-5 (0.4) - 7.5 9.4 - 1.3 4 BIO Web of Conferences 30, 02004 (2021) https://doi.org/10.1051/bioconf/20213002004 ILS 2020

4 Conclusion By the adsorption of transition metal (Ag, Co, Mo, W and Mo-W mixtures) nanoparticles from reverse micellar solutions on NaY, HY, and ZSM-5 zeolites, samples of modified zeolites were obtained, the adsorption properties of which with respect to air macrocomponents differed from those of the initial adsorbents. Ag/NaY zeolite with a silver content of 0.4 wt. % had the highest selectivity to argon and the lowest surface polarity among the modified zeolites. Electronic photos of the Ag/NaY zeolite surface after interaction with RMS showed a uniform distribution of Ag NPs (1-3 nm) on the zeolite surface. We believe that the decrease in the polarity of the NaY zeolite is due to the uniform distribution of silver NPs on the surface of the adsorbent, which screen sodium cations, which are active centers of nitrogen and oxygen sorption. As shown in works by Golubeva [10-13], differences in the acidity of the surface of zeolite matrices did not effected on the stability of silver NPs in their structures. In zeolites HY and ZSM-5, the centers of nitrogen and oxygen sorption are apparently the protons of hydroxyl groups. The arrangement of silver nanoparticles on the surface of the HY zeolite and the screening of protons by them led to a 2-fold decrease in nitrogen adsorption and a slight decrease in oxygen adsorption, which are apparently adsorbed on the Ag/HY zeolite due to nonspecific forces. Judging by the equilibrium adsorption values, argon is adsorbed better on Ag/HY zeolite due to its higher molecular weight. In contrast to NaY and HY zeolites, modification of ZSM-5 zeolite with a binder of silver (and cobalt) nanoparticles led to an increase in oxygen adsorption by 1.7 times. A possible reason for the increase in oxygen adsorption is the presence of a binder (γ-Al2O3). When deposited, metal nanoparticles could appear on both alumina and zeolite. References 1. F.E. Epiepang, X. Yang, J. Li et al., Chem. Eng. Sci., 198, 43, (2019) 2. X. Yang, F. E. Epiepang, J. B. Li, Y. Wei et al., Chem. Eng. Journal, 362, 482, (2019) 3. X. Yang, F. E. Epiepang, Y. S. Liu and R. T. Yang, Chem. Eng. Sci., 178, 194, (2018) 4. Y. R. Wang and R. T. Yang, ACS Sustain. Chem. & Eng., 7, 3301 (2019) 5. F. Wu, M. D. Argyle, P. A. Dellenback, M. Fan, Progress in Energy and Combustion Science, V.67, 188-205 (2018) 6. A. A. Odintzov, M. O. Sergeev, A. A. Revina, O. A. Boeva, Uspekhi v himii i himicheskoj tekhnologii, 27, №6, 75–79 (2013) 7. A.J. Armenta-González, R. Carrera-Cerritos, A. Moreno-Zuria, et al., Fuel, V. 167, 240–247 (2016) 8. Belyakova L.D., Larionov O.G., Revina A.A. at al., Protection of Metals, 44, 164-169 (2008) 9. O. G. Larionov, A.A. Volkov, A. A. Revina, et al., Sorbtsionnye Khromatogr. Protsessy, 5, 713 (2010) 10. O. Y. Golubeva, N. Y. Ternovaya, N. V. Mal’tseva, D. Meyerstein, Glass Phys Chem, 38, 455–459 (2012) 11. O. Y. Golubeva, N. Y. Ul’yanova, L. N. Kurilenko, Fiz. Khim. Stekla, 39, 913–919 (2013) 12. O. Y. Golubeva, N. Y. Ul’yanova, Glass Phys Chem, 41, 537–544 (2015) 13. N. Y. Ul’yanova, O. Y. Golubeva, Fiz. Khim. Stekla, 5, 479–485 (2018) 14. J. Talebi, R. Halladj, S. Askari, Journal of materials science, 45, 12, pp. 3318–3324 (2010) 15. Q.H. Tran, V. Q. Nguyen, A.T. Le, Adv. Nat. Sci: Nanosci. Nanotechnol, V. 4, p. 033001 (2013) 16. J. García-Barrasa, J. M. López-de-Luzuriaga, M. Monge Central European Journal of Chemistry, 9, 7–19 (2011) 17. W.C.M Gomes, A.O.W. Neto, P.M. Pimentel, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 426, 18–25 (2013) 18. D. Singha, N. Barman, K. Sahu, Journal of colloid and interface science, 413, 37–42, 2014. 19. Revina, A.A., RF Patent 2312741 (2007) 20. Revina, A.A., RF Patent 2322327 (2008) 21. S. S. Pavlov, E.S. Astapova, Vestnik amurskogo gosudarstvennogo universiteta. seriya: estestvennye i ekonomicheskie nauki, 49, 39–42 (2010) 22. E.S. Astapova, V.S. Radomskiy, L.L. Korobicyn and A,V. Filimonov, Nauchno-tekhnicheskie vedomosti SPbGPU. Fiziko-matematicheskie nauki, 49, 54–57 (2010) 23. Y. I. Shumyatskii, Promyshlennye adsorbtsionnye protsessy(Kolos, Moscow, 2009) 5 BIO Web of Conferences 30, 02004 (2021) https://doi.org/10.1051/bioconf/20213002004 ILS 2020

Catalytic and adsorption properties of materials based on natural alumosilicate modified with carbon Mikhail Fidchenko1* , Marina Alekhina1 , Anastasia Beznosyuk1 , and Alika Varnavskaya1 1D.Mendeleev University of Chemical Technology of Russia, Moscow, Russia Abstract. Research of adsorption and catalytic properties of carbon mineral materials made of natural alumosilicates modified by carbon of organic substances for water purification from various organic impurities 1 Introduction One of the most used and effective adsorbents and catalyst components for water purification from organic impurities is activated carbon (AC) but activated carbons are expensive materials. Along with AC one of the most used materials are carburized materials made of cheaper primary products and production waste [1-2]. Natural clays that contain transition metals can be used as a porous matrix for this type of adsorbents and catalysts. The advantages of using natural clays over other materials are availability, cheapness, availability of sufficient raw materials, non-toxicity. Various carbonic materials can be used as modifiers. One of the carbon materials that can be used as a main product are used car tires [3]. The purpose of this research work was the synthesis of carbon-mineral materials based on natural montmorillonite clays containing iron and tire crumbs, as well as the study of their adsorption and catalytic properties. 2 Experimental A sample of montmorillonite clay with the iron content 7,8 mass % was grinded, sifted and fractions sized 0.25-1 mm were selected. Tire crumbs (product of the car tires recycling) were used as a carbon source. A mixture of clay and tire crumbs was granulated; the resulting granules were subjected to airless pyrolysis at 350-800оС. The elemental composition of specimens was determined by X-ray fluorescence using the X-MAX INCA ENERGY attachment (Oxford Instruments, Great Britain) on a JEOL JSM-6510 LV electron microscope (JEOL, Japan) at the D. Mendeleev Center of Collective Use. To determine the structural and energy characteristics of aerogel samples, the nitrogen adsorption isotherms were recorded at 77 K with a Nova 1200е volumetric installation (Quantachrome, the United States). Before isotherms were taken, the samples were degassed at 250°С and a residual pressure of 10–3 mm Hg within 4 h. The specific surface area Ssp of the samples was calculated using the BET equation, and the volume of the adsorption * Corresponding author: [email protected] space of micropores and characteristic adsorption energy (W0, Е0) were calculated using the Dubinin– Radushkevich equation. The total sorption volume of meso- and micropores, Vs, was determined from the nitrogen adsorption isotherm at a relative pressure of 0.995. The average diameter of mesopores (Dmeso) was determined by the BJH method from the desorption branch of the isotherm. Isotherms of water vapor adsorption on all carbonmineral material (СMM) samples at 20°C were obtained by the desiccator method. The equilibrium value of water vapor adsorption, aH2O in (g/100g) of the sample was calculated by the formula: (1) where: m1 is the mass of the bottle with the material sample after the end of the sorption process, (g); m2 - mass of a bottle with a sample of material after drying the sample to constant mass, (g); m3 is the mass of the bottle dried to constant mass, (g). The adsorption of nonionic surfactants from solutions on the obtained adsorbents was studied using the example of neonol AF9-10. Weighed portions of pre-dried adsorbents of different weights (0.125–1.6 g / L) were added to model solutions of neonol AF9-10 with a concentration of 50 mg/L. The flasks were kept in a dark place and their contents were shaken for 7 days. The equilibration time was determined in preliminary experiments. After shaking, the sample was filtered, the solution was centrifuged and analyzed. The concentration of neonol in the initial and equilibrium solutions was determined using a Specord M40 spectrophotometer at 272 nm. The amount of excess adsorption of neonol was calculated by the formula: (2) where Г is the amount of excess adsorption of neonol, (mg/g); с0 - concentration of the initial solution, (mg/l); cp - equilibrium solution concentration, (mg/l); V is the volume of the solution, (l); g is the mass of the adsorbent, (g). The determining error was within 2%. The catalytic properties of the samples were studied in the reactions of decomposition of hydrogen peroxide and © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02005 (2021) https://doi.org/10.1051/bioconf/20213002005 ILS 2020

destructive oxidation of neonol AF9-10 in an aqueous solution. Decomposition of Н2О2 was performed in the static reactor with a stirrer. Sample of a sorbent weighed 0.1 g was placed into the reactor, where a solution of Н2О2 with a concentration of 150 mg/l with a volume of 50 ml was injected. Process temperature was at 70°C, time of contact -1 hour. After phase separation, the residual concentration of hydrogen peroxide was determined by iodometric titration. The degree of decomposition of hydrogen peroxide, α (%) was determined by the formula: (3) Neonol was oxidized with hydrogen peroxide at 70°C in the dynamic mode. The CMM sample was placed in a jacketed reactor, through which a model solution containing neonol and hydrogen peroxide was passed at a flow rate of 0.47 l/h. The height of the sample layer was 3 cm, the pH of the solution was 10, the initial concentration of Н2О2 was 100 mg/l and of neonol was 50 mg/l). At the outlet, samples of the solution were selected and the content of Н2О2 and neonol AF9-10 was determined. 3 Results and discussion The textural characteristics of the samples pyrolyzed at temperatures of 500°C and 750°C are presented in Table. 1. The obtained materials had a mesoporous structure. The results showed that an increase in the pyrolysis temperature led to a decrease in the values of the specific surface area and volume of micropores. The total sorption volume of meso- and micropores (Vs) increased, while the average diameter of mesopores decreased. The change in the texture characteristics is associated with the filling of the montmorillonite matrix of the CMM with carbon. These results were confirmed by X-ray phase analysis (fig. 1 a, b). The diffraction patterns clearly show an increase in the number of peaks corresponding to graphite-like deposits on the surface of the CMM sample pyrolyzed at 800°C. Depending on the pyrolysis temperature, the carbon content on the montmorillonite surface, as shown by elemental analysis, ranged from 17 to 48 mass %, which can be differently affect the adsorption and catalytic properties of CMM. The iron content in the pyrolyzed samples was 2.5-4.0 mass %. Isotherms of water vapor adsorption on CMM samples at 20°C are shown in Fig. 2. Table 1. Texture characteristics of CMM samples. Pyrolysis temp. ( оС) BET Specific surface area Ssp (m2 /g) Parameters of the DubininRadushkevich equation Vs (cm3 /g) Dmeso BJH (nm) W0 (cm3 /g) E0 (kJ/mol) 500 61,7 0,03 11,9 0,05 27,9 750 15,6 0,01 14,1 0,35 4,0 Fig. 1. Diffraction patterns of CMM samples pyrolyzed at 500 (a) and 800 ° С (b). Fig. 2 Isotherms of water vapor adsorption at 20оС on samples of carbon-mineral material pyrolyzed at different temperatures. The CMM samples showed a general decrease in the amount of adsorbed water with an increase in the pyrolysis temperature during the synthesis of the material, which is associated with a more complete coverage of the inner surface of montmorillonite with a carbon layer as a result of carbonization. The maximum value of adsorption attained on the sample of the initial montmorillonite was 264 mg/g. This is almost 1.5 times higher than the maximum value obtained for pyrolyzed CMMs. The presence of a convex region on the isotherms of water vapor adsorption by the samples (Fig. 3) suggests that in the region of low relative pressures, adsorption occurs mainly on the primary adsorption centers, which are metal cations and protons of hydroxyl groups of montmorillonite. If we assume that they are energetically 2 BIO Web of Conferences 30, 02005 (2021) https://doi.org/10.1051/bioconf/20213002005 ILS 2020

homogeneous, then the Langmuir equation can be used to describe the initial sections of water vapor adsorption isotherms by pyrolyzed samples and to determine the number of primary adsorption centers (PAC). Fig. 4 shows the dependence of the number of PACs calculated by the Langmuir equation (am, (mg/g)) on the pyrolysis temperature of the samples. Fig. 3. The initial sections of water vapor adsorption isotherms by samples pyrolyzed at different temperatures Fig. 4 Dependence of the number of surface adsorption centers of water vapor on the surface of samples of carbon-mineral material depending on the pyrolysis temperature. The value of am decreases with an increase in the pyrolysis temperature of material granules, which indicates that a significant part of PAC is destroyed or screened by carbon during the carbonization of the material. Fig. 5 shows the isotherm of excessive adsorption of neonol AF9-10 from aqueous solutions at 20°C on a CMM sample pyrolyzed at 750°C. Here, for comparison, the isotherm of adsorption of neonol AF9-10 at 20°C on active carbon F-300 is shown [4]. As can be seen from the figure, the CMM sample is somewhat inferior in capacity to the activated carbon F300, but it can be used for the adsorptive purification of wastewater from neonol AF9-10 and other surfactants. The CMM samples were tested in the catalytic decomposition of hydrogen peroxide. The results are presented in Table. 2. Fig. 5. Isotherms of excessive adsorption of neonol AF9-10 from aqueous solutions at 20°C on a carbon-mineral adsorbent obtained at a pyrolysis temperature of 750 ° C and activated carbon F-300 [4]. Table 2. Results of experiments on the decomposition of hydrogen peroxide on CMM. Sample pyrolysis temperatur e (оС) Solution volume Na2S2O3 (ml) Residual quantity H2O2 (mg/l) Decompositi on of Н2О2 (%) 350 6.8 116.4 22 400 5.9 100.3 33 450 5.5 93.5 37 500 4.7 79.9 46 550 5.1 86.7 42 600 5.2 88.4 41 650 4.8 81.6 45 700 2.8 47.6 68 750 2.5 42.5 71 800 2.6 44.2 70 The results of experiments on the decomposition of H2O2 on carbon-mineral materials showed that CMM can be used as a catalyst for the decomposition of hydrogen peroxide in the processes of oxidative destruction of surfactants in wastewater [5]. The degree of decomposition of Н2О2 of the best samples was 70-71% at an initial Н2О2 concentration of 150 mg/l and a pH value of 10; for activated carbon BAU under the same conditions the value of the degree of decomposition of Н2О2 was 42% [6]. The CMM sample, pyrolyzed at 750 ° C, was researched in the process of destructive purification of wastewater from neonol AF9-10 in a dynamic mode. The results are presented in Table. 3. As a result of the experiment, the maximum oxidation state of the surfactant which was 86.4% was reached on 30th min. The subsequent decrease in the oxidation state is apparently associated with the decomposition of hydrogen peroxide, which must be added into the solution in dosage. 3 BIO Web of Conferences 30, 02005 (2021) https://doi.org/10.1051/bioconf/20213002005 ILS 2020

We can conclude that CMM have a sufficiently high catalytic activity and can be used for destructive purification of solutions from nonionic surfactants such as neonol AF9-10. The conducted research allows us to conclude that adsorbents and catalysts based on CMM are promising materials for purifying wastewater from organic compounds. Table 3. Oxidation of neonol AF9-10 with hydrogen peroxide on a CMM sample pyrolyzed at 7500C in a dynamic mode. Time (min) Residual content of neonol AF9-10 (mg/l) Solution volume (l) Decompositio n of neonol AF9-10 (%) 30 6.8 0.2 86.4 60 10.2 0.4 79.7 90 15.1 0.6 69.7 120 17.3 0.8 65.5 150 18.9 1 62.1 180 16.3 1.2 67.3 4 Conclusion The results showed that pyrolysis of granules from a mixture of natural montmorillonite clay and tire crumbs in an airless condition leads to the production of a carbonmineral material with the properties of an adsorbent and a catalyst. Elemental analysis showed that the iron content in the pyrolyzed samples was 2.5-4.0 mass %. Carbon deposits on the montmorillonite surface in the samples varied from 17 to 48 mass %. The hydrophobization of the clay surface manifested itself in a decrease in the adsorption of water vapor by CMM samples with an increase in the pyrolysis temperature. Example of the adsorption of neonol AF9-10 from aqueous solutions showed that in terms of adsorption activity to nonionic surfactants, the obtained CMM is slightly inferior to industrial activated carbons, but it may well be recommended for use as an adsorbent for purifying wastewater from high molecular weight organic pollutants from various industries. It was found that with an increase in the pyrolysis temperature, an improvement in the catalytic properties of CMM samples was observed in the processes of the decomposition of Н2О2 and the oxidation of neonol AF9- 10 with hydrogen peroxide. Acknowledgment Special thanks to D. Mendeleev Centre of Collective Use at D. Mendeleev University of Chemical Technology of Russia for performed research. References 1. X. Yang, F. Li, M. Xia, F. Luo, Y. Jiang, Investigation on the micro-structure and adsorption capacity of cellulosic biomass carbon based montmorillonite composite (Elsevier, Amsterdam 256, 2018) 2. D. Tong, C. Wu, M. Adebajo, G. Jin, W. Yu, S. Ji, C. Zhou, “Applied Clay Science Adsorption of methylene blue from aqueous solution onto porous cellulose-derived carbon/montmorillonite nanocomposites (Amsterdam: Elsevier, 161, 2018) 3. K.S. Shykhaliev, Eurasian Union of Scientists (ESU), 6, 80–81 (2016) 4. P.V. Uchanov, I.N. Kamenchuk, N. Zholdabekova, V.M. Mukhin, Chemical Industry Today, 9, 50-56 (2014) 5. M.M. Fidchenko, L.V. Omelyanenko, G.G. Otyrba, M.B. Alekhina, Collection of abstracts of the YI Russian conference with international participation "Technical chemistry. From theory to practice," (Institute of Technical Chemistry, Ural Branch of the Russian Academy of Sciences, Perm, 185, (2019) 6. A.I. Morozov, A.I. Rodionov, I.N. Kamenchuk, A.A. Kurilkin, Advances in chemistry and chemical technology, (D. Mendeleev University of Chemical Technology of Russia, Moscow, 28, 2014) 4 BIO Web of Conferences 30, 02005 (2021) https://doi.org/10.1051/bioconf/20213002005 ILS 2020

Optimal conditions of acid modification of Bentonite-Like Clay Natalya Gorbunova1* and Aleksandr Vezentsev1 1Belgorod State National Reasearch University, General Chemistry Department, 308015 Belgorod, Russia Abstract. The results of mathematical modeling of the bentonite-like clay’s process of modifying various concentrations sulfuric acid depending on time the modification process is given in the presented article. As a result, the optimal parameters of this process were determined by the experimental and calculation method. 1 Introduction Implacable pollution of water resources occurs in the process of development of industrialization. Therefore, an important stage in human life is access to clean drinking water. One of the main methods of water fine purification is adsorption, it is possible to purify water from heavy metal ions and organic contaminants [1, 2]. Activated carbons are the best-known adsorbents, but they are relatively expensive [3]. Recently, more and more often, finely-dispersed rocks are used to purify water or air. In particular, bentonite-like clays have the best characteristics - the ratio of adsorption capacity to price. Bentonite-like clay containing at least 60 mass. % montmorillonite, it is an effective adsorbent for heavy metal ions Cu2+ , Pb2+ , Ni+ , Cd2+ [4, 5, 6]. Montmorillonite is a layered hydroaluminosilicate from the smectites group. A distinctive feature of which is the ability to swell the crystal lattice, it consists of two tetrahedral silicon-oxygen layers and the octahedral - aluminum-hydroxyl oxygen layer located between them. It should be noted that when heterovalent isomorphic substitution of Si4+ on Al3+ occurs in the tetrahedral layer or isomorphic substitution of Al3+ on Mg2+ occurs in the octahedral layer, a negative charge arises, which is compensated by the presence of metal cations in the interlayer space. The role of compensating cations may be Na+ , К + , Ca2+ , Mg2+ or Al3+, it depends on the clay mineral synthesis conditions. The cation exchange capacity in this case is due to non-stoichiometric substitutions in the octahedral or in the tetrahedral layers. Wherein, the ability to cation exchange in some cases can cause excess negative charges on the side faces of crystals or surface silanol groups. The scheme of montmorillonite crystal lattice is shown in Fig. 1. Most often, montmorillonite-containing clay is in close interaction with other rocks, which requires its purification from impurities of accessory minerals. An enhance method is used to improve the sorption characteristics of clays, including elutriation followed by sedimentation analysis. In addition, it is preferable to find more active ions hydrogen in the interlayer space of * Corresponding author: [email protected] montmorillonite than other elements. The mineral is modified with various solutions of acids and/or salts in order to increase the adsorption efficiency. In this case, an increase in the interplanar spacing d (001) a from 12 Å to 18 Å (distance d increases from 3 Å to 9 Å) is achieved, and as a result, the improvement of the mineral adsorption properties, aimed at sorption of harmful substances [7,8]. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

Fig. 1. The scheme of the crystal lattice of montmorillonite This clay used in the work does not contain exchange H+ and A13+ in its natural form. The H+ and A13+ cations appear as a result of the replacement of mono- and divalent cations of alkali and alkaline earth metals, which occupy exchange positions on the inner surface of clay minerals with hydrogen ions of an activating acid. H+ ions not only occupy exchange positions, but, penetrating the structure of montmorillonite, cause partial destruction of it and displace A13+ ions. As with hydrogen ions, aluminum ions occupy exchange positions and create the exchange (H+ and A13+) acidity of the adsorbent. In industrial conditions, enumeration of adsorption parameters for energy-efficient cleaning is not applicable. The most frequently, the erudition and intuition of the researcher determines the duration of the interaction of bentonite and solutions of acids/salts, the ratio of solid and liquid phases, the concentration of acids and salts [9]. Enumeration of modification technological is not applicable in an industrial environment. We carried out mathematical modeling of the cation exchange process when modifying montmorillonite containing clay with sulfuric acid, depending on its concentration and exposure time. The physicochemical parameters of the acid treatment of bentonite-like clay of the ‘Polyana’ deposit, Belgorod Region, Russian Federation were determined experimentally. The process of modifying the initial bentonite-like clay was carried out to identify patterns of change in the chemical composition (Wt%) of clay material based on montmorillonite [10]. 2 Experiment Clay of the ‘Polyana’ deposit in the Shebekinsky district of the Belgorod region, the content of montmorillonite 40-60 Wt%, was selected as the initial raw material. After elutriation, particles were selected with a size of not more than 10 μm by sedimentation method. Then the enhanced product was dried in an oven at a temperature 100±5 оС and ground in a porcelain mortar with a porcelain pestle to a particle size of ≤50 μm. After that, the acid treatment of the material 10, 20, 30 Wt% sulfuric acid at a reaction time of 1 and 6 hours at 97-98 0С with constant stirring took place. The ratio of solid and liquid phases was 1: 3 (clay: acid). Then the change in the cationic composition of the products of acid treatment was evaluated, namely, an analysis of the content of Na+ , K+ , Ca2+ cations in the interplanar spacing of the layered silicate was carried out. It was found that the number of cations tends to a minimum, therefore, these cations are replaced by H+ ions. The chemical composition of the test samples was studied using an EDAX energy dispersive analyzer combined with a Quanta 200 3D ion-electron scanning microscope. The data on the change in cation content in the interlayer space of clay of the Polyana deposit in the Shebekinsky district of the Belgorod region are shown in the table I. As a result of the experiments, data were obtained that allow us to search for patterns on the change in the cation content in bentonite-like clay, these patterns can be represented in graphical form. But, the data from the tables is not enough to build full-fledged graphs that reflect the laws of composition change; for this reason, the function values presented in the table were interpolated. The authors chose bicubic spline interpolation, as the most adequately reflecting the desired pattern. Table 1. Change in cation content in montmorillonitecontaining clay Clay process conditions Mass content of the element Na+ К+ Сa2+ Enhanced clay 3.81 2.,64 3.92 10 % H2SO4 solution 1 hour 3.04 2.61 2.39 20 % H2SO4 solution 1 hour 1.81 2.52 1.59 30 % H2SO4 solution 1 hour 1.61 2.44 1.04 10 % H2SO4 solution 6 hours 0.21 1.64 0.51 20 % H2SO4 solution 6 hours 0.0 1.58. 0.21 30 % H2SO4 solution 6 hours 0.0 1.34 0.0 We have adopted the minimum content of exchangeable cations as a criterion for the adsorption capacity of the obtained substance. It has been established that minerals (except montmorillonite), which may contain Na+ , Ca2+ cations, are absent in the studied clay. K+ cations can be included in the interlayer positions of illite, as well as contained in the structure of montmorillonite. The results of chemical analysis suggest that the Naform of montmorillonite containing clay, which has greater sorption activity compared to other known forms of bentonite-like clays, is before us. This is due to the fact that Na+ ions, being in the exchange positions of the crystal lattice of montmorillonite, are more easily exchanged for ions from the solution. All necessary calculations are performed in the SciLab environment using special macros. Three-dimensional graphs of the presented experimental results of the modification of bentonite-like clay with 10, 20, 30% sulfuric acid for 1 hour and 6 hours are shown in Fig. 2. If the minimum content of exchangeable cations is taken as a criterion for the adsorption capacity of the obtained substance, according to the equation: (1) where: P is the content of exchangeable cations; i is the row number of the array of values of the exchangeable cations content, showing Wt% acid content, array column number showing the reaction time in the acid-clay system. Using the least squares method to search for functional dependences of changes in the presence of Na+ , Ca2+, K+ cations at the extreme points of the modification time, we use the following equation as the source [11]: , (2) where x is the concentration of acid, Wt %. 2 BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

Fig. 2. Dependence of the content of sodium, potassium and calcium cations in bentonite-like clay on acid concentration and processing time A macro for searching the equation coefficients of the exchange cations of sodium, potassium and calcium was developed by the authors of [10]: clear //Duration, hour. R=1:0.005:6 //Acid concentration AC=10:0.2:50 // Determination of the sum of the cation content, wt.% for each element // Index 2 =1/2 // We accept the minimum minimum number of cations, wt.% equal to 10 Pmin=100 for i=1:length(AC) PNa1(i)=(0.0002060-0.0000048*AC(i))*(- 137.8602-AC(i))^2 PNa2(i)=(0.0003062- 0.0000142*AC(i))*(11.186818-AC(i))^2 PK1(i)=(0.0007318-0.0000129*AC(i))*(- 60.616989-AC(i))^2 PK2(i)=(0.0007616-0.0000166*AC(i))*(- 47.07344-AC(i))^2 PCa1(i)=(0.0114369- 0.0004024*AC(i))*(11.184091-AC(i))^2 PCa2(i)=(0.0003435+0.0000090*AC(i))*(- 99.557432-AC(i))^2 for j=1:length(R) // For sodium if PNa1(i)<=PNa2(i) PNa(i,j)=PNa1(i)+(0.5+0.005*j)*(PNa2(i)- PNa1(i))/max(R) else PNa(i,j)=PNa1(i)-(0.5+0.005*j)*(PNa1(i)- PNa2(i))/max(R) end // For potassium if PK1(i)<=PK2(i) PK(i,j)=PK1(i)+(0.5+0.005*j)*(PK2(i)- PK1(i))/max(R) else PK(i,j)=PK1(i)-(0.5+0.005*j)*(PK1(i)- PK2(i))/max(R) end // For calcium if PCa1(i)<=PCa2(i) PCa(i,j)=PCa1(i)+(0.5+0.005*j)*(PCa2(i)- PCa1(i))/max(R) else PCa(i,j)=PCa1(i)-(0.5+0.005*j)*(PCa1(i)- PCa2(i))/max(R) end P(i,j)=PNa(i,j)+PK(i,j)+PCa(i,j) if P(i,j)<Pmin then Pmin=P(i,j) AC_min=AC(i) min_R=1+0.005*(j-1) end end end print(%io(2),AC_min, min_R,Pmin) 3 BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

surf(R,AC,P) Thus, Equation for sodium: The reaction time of acid and clay 1 hour – , (3) The reaction time of acid and clay 6 hours – , (4) Equation for potassium: The reaction time of acid and clay 1 hour – , (5) The reaction time of acid and clay 6 hours – , (6) Equation for calcium: The reaction time of acid and clay 1 hour – , (7) The reaction time of acid and clay 6 hours – , (8) 3 Results and discussions Fig. 3 shows graphs of the modification’s results of the of bentonite-like clay with 10, 20, 30% sulfuric acid for 1 hour and 6 hours to compare the experimental and calculated data on the amount of sodium, potassium and calcium cations in bentonite-like clay with modified sulfuric acid depending on the acid concentration and processing time. In these figures, the intersection points of the calculated curve and the curve constructed from experimental data are indicated by the letters A and B. Since the curve reflecting the calculated content of sodium, potassium, and calcium cations in the bentonite-like clay is constructed after interpolation of the experimental data, it is likely that the optimum acid concentration for each particular element is found within a given time (1 hour and 6 hours) between these points. Obviously, the amount of sodium cations decreases with increasing acid concentration. This process is clearly illustrated in Fig. 3-a. The concentration of acid goes by the wayside with an increase in the reaction time of solid and liquid phases, since the values of the content of sodium cations when treated with acid for 6 hours are several times cations is zero when the concentration of 18 wt.% H2SO4 is modified and the reaction time is 6 hours. The optimal concentration is achieved when the value is equal to 25 wt.% at a modification time of 1 hour, and 18% at a reaction time of 6 hours. A further increase in concentration does not lead to a subsequent decrease in the amount of sodium cations. It should be noted that with an increase in acid concentration, partial destruction of the crystal lattice of montmorillonite is possible. Fig. 3. Dependence of cation content in bentonite-like clay on acid concentration and processing time: a) for sodium, b) for potassium, c) for calcium 4 BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

Fig. 3-b shows the congruent graphical dependencies of the graphs of changes in potassium content depending on the acid concentration and duration of treatment. The fact of congruence allows us to estimate the change in the content of potassium cations beyond the limits specified during the experiment. In the case of potassium, the optimal concentration value is 30 wt% at an interaction time of 1 hour and 6 hours. Since the lowest content of potassium ion-exchange cations is achieved with a modification time of 6 hours, this value of time should be noted as optimal. Fig. 3-c shows the change in the content of calcium cations. In this case, the content of calcium cations decreases with an increase in the concentration of sulfuric acid. A rapid decrease in calcium ions occurs at a time of interaction of solid and liquid phases for 1 hour, when the reaction time is 6 hours, the nature of the curve is gentler in the decrease direction. It can also be concluded that the range of sulfuric acid concentration, which is probably the optimum for a processing time of 1 hour, lies in the range of 16-28 Wt%, that is, the interval between points A3 and B3. It can also be concluded that the range of effective concentration of sulfuric acid lies in the range of 16-28 Wt%, similar to the graph of changes in the content of sodium cations. Since when the modification time is 1 hour, the necessary complete removal of calcium cations does not occur, we decided to conduct a process lasting 6 hours under similar conditions, namely at 10, 20, 30 wt.% sulfuric acid. The optimal value of the concentration of sulfuric acid ranges from 29-30 wt.% with a duration of modification of 6 hours. It is worth noting that complete removal of calcium from the interplanar distance occurred during the reaction of sulfuric acid and clay, the content of Ca2+ cations became equal to 0.0 when treated with 30% sulfuric acid with a reaction time of 6 hours. Calcium dihydrosulfate, having a larger molecule size than can fit in the interplanar spacing of montmorillonite, can form on the outer surface of the crystal lattice of minerals that make up bentonite-like clay. Summing up for each element, we can distinguish the following parameters for effective modification: to completely remove sodium from the interlayer space, it is necessary to treat bentonite-like clay with 18 wt% sulfuric acid for 6 hours, for the maximum possible removal of potassium - 30% sulfuric acid for the same 6 hours, for complete removal of calcium - 29% sulfuric acid for 6 hours. The modifying was tested in the presence of all ionexchange cations in the interlayer space of bentonite-like clay. Therefore, rigid condition - 30 mass. % sulfuric acid with a reaction time of 6 hours is necessary to completely remove all cations. Graphical dependences of the change in the content of exchangeable cations Na+ , K+ , Ca2+ in bentonite-like clay depending on the acid concentration and the duration of the modifying were constructed after analysis of the obtained experimental data. A surface showing the dependence of the total content of exchangeable cations wt% on the acid concentration and the duration of the treatment process is presented in Fig. 4. Fig. 4. Dependence of the total content of sodium, potassium and calcium cations in bentonite-like clay on acid concentration and processing time The optimal design conditions for the modification of the initially specified technological parameters (sulfuric acid concentration of 10, 20, 30 wt.% and the duration of the modification of 1 and 6 hours), namely 4 hours 58 minutes and 30 mass. % H2SO4, were obtained by performing the necessary calculations in a SciLab environment. 4 Conclusion By the calculation method, we have confirmed that it is optimal to use 30 wt.% sulfuric acid. And for the first time it was shown that the optimal duration of clay treatment with acid is 4 hours 58 minutes. Thus, we can safely conclude that the implemented mathematical modeling in the course of chemical experiments gives a clearer picture for the subsequent work. Studies have made it possible to formulate patterns of changes in the content of various elements cations depending on the concentration of acid and the reaction time in the acid-clay system. The optimal parameters for modifying the starting material with sulfuric acid were revealed. The optimal calculated modification parameters are as follows: 30% sulfuric acid concentration and modification time 4 hours 58 minutes. Using the SciLab application, in accordance with the recommendations set forth in [12], it was possible to develop a set of software procedures for processing experimental data and obtaining functional dependencies describing the found patterns. If you expand the scope of the study or conduct data processing of any other experiments, these procedures will also reduce the processing time of the results. When obtaining functional dependencies, the general equation of a quadratic function was used, but this does not exclude its replacement, by any other. Thus, the automation of calculations for the processing of experimental data not only made it possible to find functional dependencies with the best approximation, but also made it possible to study many 5 BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

options for a short period of time with respect to the duration of the experiments. References 1. L.Yan, B.Wen, , G. Owens, Journal of Hazardous Materials, 156, pp. 499-508, (2008) 2. N.M. Gorbunova, A.I. Vesentsev, International Scientific and Technical Conference ‘Innovative Ways to Solve Actual Problems of Environmental Management and Environmental Protection’, 4-8 June 2018, Alushta, Russia, (2018) 3. A.I. Vezentsev, E.V. Kormosh, L.F. Peristaya, A.V. Shamshurov, R.A. Cherkasov, J. Engineering and Applied Sciences, 9, 11, P. 2358-2366, (2014) 4. A.V. Sharapova The treatment of wastewater from heavy metals under the influence of ultrasound and the disposal of anti-icing fluids using natural sorbents: inaugural dissertation Candidate of chemical sciences, Ulyanovsk, P.114, (2015) 5. A.I. Vesentsev, S.V. Korolkova, N.A. Volovicheva, S.V. Kudiakova, Sorbtsionnye i Khromatograficheskie Protsessy, 9 (6): pp. 830-834. (in Russian), (2009) 6. N.A. Volovicheva, A.I. Vesentsev, S.V. Korolkova, N.F. Ponomareva, Water: chemistry and ecology, 9, pp. 60-66, (in Russian), (2011) 7. E.S. Klimov, M.V. Buzayeva, Natural sorbents and complexons in sewage treatment, Ulyanovsk, ULGTU, p. 201, (2011) 8. N.G. Vasil'ev, V.V. Goncharuk, Synthesis and physical and chemical properties of inorganic and carbon sorbents, Kiev, Naukova dumka, pp.58-72. (1986) 9. S.A. Semenov, Educational-methodical manual, Moscow, IPC MITHT, P. 93, (2001) 10. E.V. Barannikova, A.I. Vesentsev, Belgorod State University Scientific bulletin. natural sciences. - Belgorod State National Research University Belgorod Publishing House, pp.50-52, (in Russian), (2005) 11. Certificate of the Russian Federation No.2019667682 on state registration of a computer program, 26.12.2019 г. M.S. Chepchurov,, I.A. Teterina, A.I. Vesentsev, N.M. Gorbunova// Software for processing experimental data with the search for the optimal composition of chemical mixtures. 12. Sandeep Nagar. Working with Scilab. November 2017.DOI: 10.1007/978-1-4842-3192-0_2 6 BIO Web of Conferences 30, 02006 (2021) https://doi.org/10.1051/bioconf/20213002006 ILS 2020

Graphene field effect transistor for ultrasensitive label-free detection of ATP and Adenosine Jianjian Liu* , Meng Tian, Ruihong Song, Yingxian Li, Zanxia Cao, Qiang Li, Jian Liu, Shicai Xu, Jihua Wang Dezhou University, Institute of Biophysics, Shandong Engineering Laboratory of Swine Health Big Data and Intelligent Monitoring, Shandong Key Laboratory of Biophysics, Dezhou, China Abstract. Because of unique electrical and structural properties, graphene has attracted widespread attention in biosensing applications. In this paper, a single layer of graphene was grown by chemical vapor deposition (CVD). Using graphene as the electric channel, a graphene field effect transistor (G-FET) biosensor was fabricated and used to detect adenosine triphosphate (ATP) and adenosine. Compared with traditional methods, the G-FET biosensor has the advantages of higher sensitivity and better stability. The sensor showed high performance and achieved a detection limit down to 0.5 pM for both ATP and adenosine. Moreover, the G-FET biosensor showed an excellent linear electrical response to ATP concentrations in a broad range from 0.5 pM to 50 μM. The developed graphene biosensor has high sensitivity, simple operation, and fast analysis speed, which may provide a new feasible direction to detect ATP and adenosine. Healthy sexually mature male laboratory Wistar rats, weighing 180-200 gr (“FSUE “Nursery of laboratory animals “Rappolovo”) and having been placed under quarantine not less than for 14 days, were selected for the experiment. 1 Introduction In the past few decades, a great deal of research in new sensing technologies/sensors has focused on surface enhanced Raman spectroscopy (SERS) [1], electrochemistry [2, 3], capacitor sensor, and surface plasmon resonance (SPR) [4, 5]. These sensors have been widely used for chemical and biomolecule detection, but they are difficult to operate at low cost and be miniaturized for measurement [6]. Compared with these sensors, the field effect transistor (FET) electronic sensor has been confirmed to have tremendous potential to detect many kinds of analytes due to its high sensitivity, fast detection speed, low cost and simple operation [7-11]. Graphene is a kind of nanomaterial consisting of one single layer of carbon atoms arranged in a twodimensional (2D) hexagonal crystal [12]. Graphene has many remarkable physical properties due to its unique 2D structure, such as massless carriers (electrons and holes), high transparency (97.7% for single layer), high conductivity, large specific surface area (2630 m2 •g-1 ), and high carrier mobility (up to 105 cm•V-1 •s-1 ), which is about 2-3 orders of magnitude higher than typical semiconductors like silicon [13-15]. Therefore, FET biosensors prepared using graphene have been extensively studied, and these sensors have been confirmed to have tremendous potential to detect many kinds of analyses [16-18]. Xu et al. developed a multichannel graphene biosensor for real-time reliable determination of binding kinetics of DNA hybridization [6]. Zhang et al. built a sensor platform using graphene * Corresponding author: [email protected] and metal oxide nanoparticles (NPs) for high selective and fast responsive hydrogen gas detection [19]. Wang et al. presented an affinity graphene nanosensor for detecting biomarkers in undiluted and non-desalted human serum [20]. Compared with 1D nanomaterials such as silicon nanowires [21, 22] and carbon nanotubes[23, 24], graphene has a high surface-tovolume ratio and can intimately contact with metal electrodes because of their large surface area. Therefore, it is easier to manipulate and control the channel structure in the graphene field effect transistor (G-FET) sensor, showing great advantages in manufacturing and wide applications [25-29]. In this study, we developed a G-FET biosensor to detect adenosine and adenosine triphosphate (ATP). Adenosine is an endogenous nucleoside distributed throughout the cells and can be directly phosphorylated to form adenylate. It is an endogenous anticonvulsant and an epileptic terminator [30, 31]. Adenosine signaling also plays an important role in regulating tumor immunity [32]. Adenosine triphosphate (ATP) is a multi-function chemical signaling agent that is the main energy molecule of the cells and plays a critical role in signal transduction in organisms. The fluctuation of ATP concentration is closely related to many diseases such as suppuration, hypoglycemia, and some malignant tumors [33, 34]. In addition, ATP has a wide range of applications in environmental monitoring [35, 36], drug analysis [37], food safety [38], etc. To date, many detection methods of adenosine and ATP have been previously proposed, including colorimetry [39, 40], liquid chromatography [41, 42], fluorescence analysis [43, 44], © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02007 (2021) https://doi.org/10.1051/bioconf/20213002007 ILS 2020

chemiluminescence [45], electrochemical methods [46, 47], etc. However, these methods still suffer from complex experimental operations, difficulties in preparing the reagents used, and needs for expensive instruments. In this work, we developed a field effect transistor (GFET) biosensor using graphene as an electron channel for adenosine and ATP detection. The LOD of the G-FET sensor is as low as 0.5 pM. Compared with traditional adenosine and ATP detection methods, the G-FET sensor has high sensitivity, fast analysis speed, simple operation, and low cost. This biosensor may provide a new approach for the detection of adenosine and ATP. 2 Experimental Materials and reagent. Glass substrates of indium tin oxide (ITO) conductive film were purchased from South China Xiangcheng (Shenzhen, China) Co., Ltd. ATP, adenosine and PMMA were purchased from Aladdin Industrial Corporation. Ag/AgCl electrodes were purchased from Yancheng Arduino Analytical Instruments (Jiangsu) Co., Ltd. The Cu foil (purity: 99.99 %, thickness: 50 μm) was purchased from Afaisha. (Tianjin, China). The FeCl3 was purchased from Shanghai Aibi Chemical Reagent Co., Ltd. Preparation of graphene. The copper foil was first ultrasonic cleaned with ethanol and deionized water for 20 minutes. After drying with nitrogen, the copper foil was placed in the tube furnace, and graphene film was grown on the copper substrate by chemical vapor deposition (CVD) at 1050 ℃. First, the copper foil was annealed at 1050 °C for 10 minutes with a hydrogen flow of 30 sccm to improve the quality of graphene. Then, the gas mixture of methane (10 sccm) and hydrogen (30 sccm) was introduced into quartz tube for 10 min to grow graphene. Finally, the samples were rapidly cooled to room temperature with a hydrogen flow of 30 sccm. Fabrication of G-FETs. We obtained the graphene grown on copper by wet transfer. First, polymethyl methacrylate (PMMA) was used as the protective layer to transfer the as-grown graphene films [48]. The graphene/Cu foil was spin-coated with PMMA acetone solution at low speed for 5 seconds (500 rpm) and at high speed for 30 seconds (4000 rpm) in sequence to make PMMA uniformly dispersed on the surface of the graphene. Then, the samples were baked at 150 ℃ for 30 minutes to make the PMMA layer closely adhered to the graphene. After cooling to room temperature, the PMMA/graphene/Cu was placed in FeCl3 solution to etch the copper foil. Then, we put the PMMA/graphene in deionized water to remove residual FeCl3. The obtained PMMA/graphene film was transferred onto the glass substrate, where the ITO was used as the source electrode and the drain electrode. Then, the PMMA/graphene/substrate was placed on a hot plate at 180 ℃ for 30 minutes to remove moisture and to make graphene adhered to the substrate. After that, the PMMA/graphene/substrate was immersed in an acetone solution for 24 hours to remove PMMA, thereby leaving graphene as an electric channel between the substrate source electrode and the drain electrode. Finally, a sample cell (φ = 0.5 mm) was mounted on the graphene to add adenosine and ATP for detection. An Ag/AgCl electrode was inserted as a reference electrode into the sample cell to provide a gate voltage (Vgs). Detection of ATP and Adenosine. We obtained the standard ATP and adenosine solution by adding 5.1 mg of ATP and 2.7 mg of adenosine separately to 2 ml of deionized water. Then, the standard solution was diluted to get a series of ATP and adenosine samples with different concentrations for detection. For measurements of transfer characteristics (drain current vs. gate voltage) of the GFETs, the drain voltage (Vds) was set to 10 mV. The gate voltage (Vgs) varied with a sweeping step of 10 mV, and for each step, the given Vgs pulse was maintained for 1 s to stabilize drain current (Ids) to ensure the reliability of the transfer curve. Characterization and electronic measurement. The morphology of the graphene was characterized by scanning electron microscopy (SEM ZEISS, SUPRATM55). The Raman spectrum of the graphene was measured using a Raman spectrometer (Horiba HR-800) with an excitation wavelength of 532 nm and a laser spot of about 0.1 μm. The electrical measurements were performed by a semiconductor parameter analyzer (PDA FS360) coupled with a probe station (PEH-4). 3 Results and discussion Graphene structure. Graphene film with a large area of 150 mm × 100 mm was fabricated on the copper foil. The large graphene film was cut into lots of pieces with a size of 9 mm × 9 mm × 50 μm for G-FET fabrication. The SEM image of the graphene grown on the copper foil is shown in Fig. 1a. A few light ridges were observed on the surface of the sample. The ridges are expected to be formed during the cooling process, due to the difference of thermal expansion coefficient between graphene and copper [49]. Fig. 1b shows the SEM image of the graphene film transferred onto the glass substrate. The graphene surface on the glass substrate is very flat and continuously without tears and loopholes, indicating that the graphene was well transferred. Fig. 1c shows a typical Raman spectrum collected from the graphene film. The characteristic bands of graphene D (at ~1338 cm-1 ), G (~1577 cm-1 ), and 2D (~2681 cm-1 ) were all observed in this image. The G band is due to the first-order scattering of the in-plane optical phonon 2g mode. The 2D band is regarded as characteristic bands of the graphene structure caused by a second-order process involving two photons with opposite momentum [50]. The D band is related to the structural defects, and it is due to the sp2 atoms outofplane breathing mode. In most regions of the graphene film, Raman spectroscopy shows typical characteristics of single-layer graphene with an intensity ratio I2D / IG ≥ 2 and a full width at half maximum (FWHM) of about 53 cm-1 , indicating that the grown graphene is monolayer 2 BIO Web of Conferences 30, 02007 (2021) https://doi.org/10.1051/bioconf/20213002007 ILS 2020

[51]. In addition, the D-bands associated with defects are very weak, indicating the overall high quality of graphene [52]. Fig. 1d shows the optical image of the typical graphene transferred on the SiO2/Si substrates. In the optical micrograph of the graphene film, different shades of color reflect different thicknesses of graphene. In our case, the uniform color contrast of the optical micrograph indicates that the film has excellent thickness uniformity. G-FET drain-source electric current response induced by adenosine. Using the G-FET sensor, we detected the adenosine in a wide concentration range from 0.5 pM to 50 μM (Fig. 2). Fig. 2 shows the typical transfer characteristics of the G-FET sensor to detect adenosine with different concentrations. Here, the typical ambipolar field effect characteristic of graphene was not observed, which can be explained by the doping effects from the substrate or residue produced during the graphene transfer process [53]. In the range from -0.1 to 1.4 V, the transfer curve was almost completely overlapped, show a negligible electrical response to the change of adenosine concentration. When the gate voltage was higher than 1.4 V, the electric current value increases monotonically with increasing Vg, indicating typical n-type behavior. In the n-type region, the G-FET sensor showed a sensitive electrical response to adenosine concentration. From the transfer curve, the adenosine with different concentrations can be easily distinguished. For a fixed voltage value, the electric current varies with the concentration of the adenosine solution. Especially when the adenosine concentration was lower than 1 nM, the electric current drops sharply, showing extremely high detection sensitivity. The electric current characteristics of 0.5 pM adenosine can be easily distinguished from the blank sample, indicating that the detection of limit (LOD) was even lower than 0.5 pM. The high sensitivity of the G-FET sensor can be attributed to the high surface-tovolume ratio and high electron mobility of graphene. G-FET drain-source electric current response induced by ATP. We also detected the ATP in a wide concentration range from 0.5 pM to 50 μM by using the G-FET sensor (Fig. 3). The figure shows the typical transfer characteristics of the G-FET sensor to detect ATP with different concentrations. As similar to adenosine detection, the electric current value increases monotonically with increasing Vgs, indicating typical ntype behavior. In the n-type region, when the gate voltage was higher than 1.4 V, the G-FET sensor showed a sensitive electric current response to ATP concentration. After amplifying the sensor diagram with the sweeping voltage from 1.70 to 1.85 V, it can be clearly seen that the transfer curves of GFET for different ATP concentrations can be well distinguished. The figure also shows the device electric current versus the logarithm of ATP concentration at a certain gate voltage Vgs = 1.70 V and Vgs = 1.85, respectively. For both cases, the electric current decreases linearly as the ATP concentration increases with a good linear correlation in a broad range from 0.5 pM to 50 μM, indicating that the G-FET has the high potential for quantitative detection of ATP. Fig. 1. a: SEM image of the graphene grown on copper foil, b: SEM image of the graphene transferred onto the glass substrate, c: Typical Raman spectrum of the graphene film, d: Optical microscope image of the transferred graphene film on the SiO2/Si substrate. Fig. 2. Typical transfer characteristics of the G-FET sensor for adenosine detection with different concentration with the sweep gate voltage from -1.0 to 2.0, 1.5 to 1.95 V, 1.90 to 1.95 V. Fig. 3. Typical transfer characteristics of the G-FET sensor for ATP detection with different concentration with the sweep gate voltage from -1.0 to 2.0 V, 1.65 to 1.90 V. Device electric current versus the logarithm of ATP concentration at a certain gate voltage Vgs = 1.70 V and Vgs = 1.85 V. 3 BIO Web of Conferences 30, 02007 (2021) https://doi.org/10.1051/bioconf/20213002007 ILS 2020

4 Conclusion In this work, we developed a G-FET biosensor using graphene as the conductive channel for adenosine and ATP detection. The G-FET biosensor shows high detection sensitivity, and the LOD of the G-FET sensors for both adenosine and ATP is as low as 0.5 pM. The high sensitivity of the G-FET sensor can be attributed to the high surface-to-volume ratio and high electron mobility of graphene. For adenosine detection, the sensor shows extremely high sensitive electrical response, especially when the adenosine concentration was lower than 1 nM. For ATP detection, the G-FET biosensor shows a good linear electric current response to ATP concentrations in a broad range from 0.5 pM to 50 μM, indicating the high potential for quantitative detection of ATP. The G-FET biosensor is label-free and has a low operating voltage and high measurement accuracy, providing a very promising future in the detection of important biomolecules. 5 Acknowledgment We are grateful for financial support from National Natural Science Foundation of China (11604040, 11674199), and Taishan Scholars Program of Shandong Province (tsqn201812104, tshw201502045), Qing chuang Science and Technology Plan of Shandong Province (2019KJJ017, 2020KJC004), Youth Innovation Team Lead-education Project of Shandong Educational Committee. 6 References 1. P. R. Stoddart and D. J. White, Anal Bioanal Chem, 394, 1761-1774, (2009) 2. E. Paleček and F. Jelen, Critical Reviews in Analytical Chemistry, 32, 261-270, (2002) 3. Y. Shao, J. Wang, H. Wu, et al., Graphene Based Electrochemical Sensors and Biosensors: A Review Electroanalysis, 22, 1027-1036, (2010) 4. J. Homola, Anal Bioanal Chem, 377, 528-539, (2003) 5. S. Qian, Y. Zhang, H. Yuan, et al., Sensors and Actuators B: Chemical, 260, 976-982, (2018) 6. S. Xu, J. Zhan, B. Man, et al., Nat Commun, 8, 14902, (2017) 7. C. M. Hangarter, M. Bangar, A. Mulchandani, et al., Journal of Materials Chemistry, 20, 3131, (2010) 8. Z. Fan, D. Wang, P.-C. Chang, et al., Applied Physics Letters, 85, 5923-5925, (2004) 9. W. Shi, J. Yu and H. E. Katz, Sensors and Actuators B: Chemical, 254, 940-948, (2018) 10. Y. Chen, R. Ren, H. Pu, et al., Biosens Bioelectron, 89, 505-510, (2017) 11. M. Tian, S. Xu, J. Zhang, et al., Advances in Condensed Matter Physics, 2018, 1-6, (2018) 12. K. S. Novoselov, A. K. Geim, S. V. Morozov, et al., Nature, 438, 197-200, (2005) 13. X. Du, I. Skachko, A. Barker, et al., Nat Nanotechnol, 3, 491-495, (2008) 14. Y. Wu, Y.-m. Lin, A. A. Bol, et al., Nature, 472, 7478, (2011) 15. L. Gao, W. Ren, H. Xu, et al., Nature Communications, 3, (2012) 16. S. Cheng, S. Hideshima, S. Kuroiwa, et al., Sensors and Actuators B: Chemical, 212, 329-334, (2015) 17. X. Liu, P. Lin, X. Yan, et al., Sensors and Actuators B: Chemical, 176, 22-27, (2013) 18. X. Zong and R. Zhu, Sensors and Actuators B: Chemical, 255, 2448-2453, (2018) 19. Z. Zhang, X. Zou, L. Xu, et al., Nanoscale, 7, 10078-10084, (2015) 20. X. Wang, Y. Zhu, T. R. Olsen, et al., Electrochimica Acta, 290, 356-363, (2018) 21. S. Zafar, M. Khater, V. Jain, et al., Applied Physics Letters, 106, 063701, (2015) 22. Y. Guerfi and G. Larrieu, Nanoscale Res Lett, 11, 210, (2016) 23. S. Okuda, S. Okamoto, Y. Ohno, et al., The Journal of Physical Chemistry C, 116, 19490-19495, (2012) 24. S. Z. Bisri, V. Derenskyi, W. Gomulya, et al., Advanced Electronic Materials, 2, 1500222, (2016) 25. K. Maehashi, Y. Sofue, S. Okamoto, et al., Sensors and Actuators B: Chemical, 187, 45-49, (2013) 26. P. T. K. Loan, D. Wu, C. Ye, et al., Biosens Bioelectron, 99, 85-91, (2018) 27. Y. M. Lei, M. M. Xiao, Y. T. Li, et al., Biosens Bioelectron, 91, 1-7, (2017) 28. C. Andronescu and W. Schuhmann, Current Opinion in Electrochemistry, 3, 11-17, (2017) 29. S. Szunerits and R. Boukherroub, Interface Focus, 8, 20160132, (2018) 30. L. Weltha, J. Reemmer and D. Boison, The role of adenosine in epilepsy, Brain Res Bull, (2018) 31. G. Hasko, L. Antonioli and B. N. Cronstein, Biochem Pharmacol, 151, 307-313, (2018) 32. R. D. Leone and L. A. Emens, J Immunother Cancer, 6, 57, (2018) 33. S. L. Zhang, X. Hu, W. Zhang, et al., J Med Chem, 59, 3562-3568, (2016) 34. P. de Andrade Mello, R. Coutinho-Silva and L. E. B. Savio, Front Immunol, 8, 1526, (2017) 35. G. S. Whiteley, C. Derry, T. Glasbey, et al., Infect Control Hosp Epidemiol, 36, 658-663, (2015) 36. B. D. Lewis, M. Spencer, P. J. Rossi, et al., Am J Infect Control, 43, 283-285, (2015) 37. M. Zhang, N. Zhou, P. Yuan, et al., RSC Advances, 7, 9284-9293, (2017) 38. Z. Zhang, C. Wang, L. Zhang, et al., Analytical Methods, 9, 53785387, (2017) 39. Y. Mao, T. Fan, R. Gysbers, et al., Talanta, 168, 279285, (2017) 4 BIO Web of Conferences 30, 02007 (2021) https://doi.org/10.1051/bioconf/20213002007 ILS 2020

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Investigation of sorption mechanism of methylene blue, congo red and tannic acid from aqueous solutions onto magnetic composite sorbent obtained from alkaline pretreated spent coffee grounds Pham Thanh Minh1* ,and Le Van Thuan2 , 1Center for Research and Production of Radioisotope, DaLat Nuclear Research Institute, DaLat, Vietnam 2Center for Advanced Chemistry, Institute of Research & Development, Duy Tan University, Danang, Vietnam Abstract. In this article, a novel magnetic composite material obtained from alkaline pretreated spent coffee grounds was used for investigating of the sorption mechanism of methylene blue, congo red and tannic acid from aqueous solutions. In order to clarify mechanisms were analyzed the adsorption kinetics models (external and internal diffusion; chemical kinetics (pseudo-first order, pseudo-second order); intraparticle diffusion) and the adsorption thermodynamics. The results showed that the sorption of all studied sorbates was controlled by a mixed diffusion model and a pseudo-second order and diffusion rate revealed three stage of the mass transfer. The adsorption process of methylene blue, congo red and tannic acid onto Fe3O4/PVA/APSCGs sorbent was spontaneous and endothermic. Based on the results, it was concluded that the mechanism for removal of the studied sorbates by adsorption onto Fe3O4/PVA/APSCGs sorbent may be assumed both physisorption and chemisorption. 1 Introduction Many organic compounds like dyestuffs and aromatic compounds are commonly found in textile, paper, leather, plastics, food, cosmetics, and other industries. The toxic effects of these organic contaminants on human health, and the environment requires their efficient removal from contaminated water, and this topic becomes environmentally important [1]. Methylene blue (MB) is a cationic dye. It is found in almost textile for coloring. MB can cause toxicities for animals and humans, for example: if ingested, then MB causes convulsions, dyspnea, irritation to the skin, vomiting, and diarrhea [2]. Congo red (CR) is an anionic dye. It is found in the textile, paper, printing, leather industries, etc. It is a skin, eye, gastrointestinal, and respiratory irritant [3]. Tannic acid (TA) is a natural phenolic compound. It is found in most surface water, drinking water, and wastewater from plant medicine, paper and leather industries. TA has toxicity to aquatic organisms, such as algae, phytoplankton, fish, and invertebrates [4]. Recently, in order to solve technical problems related to the separation and regeneration of sorbents after adsorption process, various methods have been used like precipitation, coagulation, filtration or magnetic separation [5]. Particularly, magnetic separation technique is an effective method for separation of samples after adsorption using an external magnetic field [6]. To improve the potential application of magnetic separation techniques in the environment, new magnetic composite materials have to be developed based on the low-cost sorbents, in there, spent coffee grounds (SCGs) are a solid waste that is interested because the approach reduces the environmental and financial costs of disposal [7]. According to data publication, the magnetic composite sorbent obtained from spent coffee grounds (SCGs) has a high adsorption capacity towards organic dyes. Zuorro et al. [8] studied using magnetic coffee silverskin for methylene blue adsorption from aqueous solutions with a maximum adsorption capacity of 556 mg/g. Safarik et al. [9] studied magnetic coffee grounds for dyes removal (acridine orange, crystal violet, malachite green, Congo red, Bismarck brown Y, and safranin O) and obtained the adsorption capacities from 9.34 to 73.4 mg/g. Safarik et al. [10] studied magnetically responsive composite materials from coffee grounds for Bismarck brown Y and safranin O removal, the adsorption capacity reaching 49.3 and 146.6 mg/g, respectively. However, there is still no study devoted to the sorption mechanism of pollutants from aqueous solutions onto this magnetic composite sorbent. The purpose of this article was to study the sorption mechanism of organic dyes (methylene blue, congo red) and aromatic compounds (tannic acid) onto magnetic composite sorbents based on alkaline pretreated spent coffee grounds. 2 Experimental Materials. SCGs were collected after brewing of Vietnamese commercial milled Robusta coffee and then *Corresponding author: [email protected] © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02008 (2021) https://doi.org/10.1051/bioconf/20213002008 ILS 2020

the samples were washed with distilled water to remove dirt and color, and dried at 105 °C for 5 hours in a convection oven. The chemicals for the preparation of magnetite (Fe3O4) particles: FeCl3.6H2O, Na2SO3, NH4OH 25%, Polyvinyl alcohol (PVA) (M.W.: 146000- 186000, degree of hydrolysis: 99.5%), and the sorbates such as Methylene blue (M.W.: 319.85 g/mol), Congo red (M.W.: 696.68 g/mol), Tannic acid (M.W.: 1701.21 g/mol). Preparation of magnetic composite sorbent. The magnetic composite sorbent (Fe3O4/PVA/APSCGs) based on alkaline pretreated spent coffee grounds (APSCGs) and particles Fe3O4 was prepared via dispersed method. To obtain this composite sorbent, the Fe3O4 particles were dispersed in PVA 2% solution. Then, the sample was heated to 80oC and added in APSCGs at 4:1 ratio of APSCGs/Fe3O4. Composite was collected by a magnet and sieved via a mesh size 315 µm. Adsorption kinetics. The adsorption kinetics of sorbates onto Fe3O4/PVA/APSCGs sorbent were studied in the change of the contact times to the adsorption capacity [11]. For each experiment, the samples (0.1 g) were mixed with 50 mL solutions sorbates of MB (0.15 mmol/L and 0.30 mmol/L), CR (0.07 mmol/L and 0.14 mmol/L ) and TA (0.03 mmol/L and 0.06 mmol/L). The experiments were performed at room temperature and pH 9 (MB), pH 5 (CR), pH 4 (TA). The concentration of sorbates in solutions was determined by spectrophotometric method using a SPECORD 210Plus spectrophotometer (Germany) at absorbance 666 nm (MB), 500 nm (CR), 275 nm (TA). The amount of adsorbed sorbates onto the magnetic composite qe (mmol/g) was calculated following to: 0 . (1) e e C C q V m Where Co (mmol/L) is the initial concentration of sorbates, Ce (mmol/L) is the equilibrium concentration of sorbates after adsorption, V (L) is the volume of solution and m (g) is the weight of sorbent. Adsorption thermodynamics. To investigate adsorption thermodynamics, adsorption isotherms were constructed at different temperatures 298 – 318 K [12]. Batch experiments were performed at different initial concentrations of sorbates with values of pH 9 (MB), pH 5 (CR), pH 4 (TA). After that, the samples were incubated in the water-batch thermostat for 8 hours. The concentration of sorbates in solutions was determined by spectrophotometric method. 3 Results and discussion Investigation of the preparation and characterization of Fe3O4/PVA/APSCGs sorbent prepared from alkaline pretreated spent coffee grounds have been published in our articles [13, 14]. The results showed that the APSCGs have a significant amount of functional groups as carbonyl, carboxyl, hydroxyl on Fe3O4/PVA/APSCGs surfaces and these functional groups can be potential adsorption centers. SEM studies indicated that the morphology of composite has a porous structure with a size in the range of 2–50 μm, resulting in good adsorption capacity with different sizes. In addition, the saturation magnetization of the Fe3O4/PVA/APSCGs sorbent was 21.5 emu/g, which is lower than the synthesized magnetite powder 73.6 emu/g but enough to separate sorbents after adsorption process. Using this technique, we were able to remove up to 95% of the sorbents from the solution [13, 14]. In this study, we used two important physicochemical aspects for the evaluation of adsorption mechanism as unit operations that are the adsorption kinetics and the adsorption thermodynamics. In addition, kinetic modeling using well - known models and adsorption thermodynamic parameters can be obtained from adsorption equilibrium constants at various temperatures. All studies were carried out trying to understand the involved mechanisms (physical and/or chemical) between sorbates molecules and on the sorbent surface. Adsorption kinetics. To study the adsorption kinetics of sorbates on the surface of Fe3O4/PVA/APSCGs sorbent, the kinetic curves were analyzed using models of external and internal diffusion, intraparticle diffusion and chemical kinetics [13]. Analysis of kinetic curves was performed with the diffusion models[13]. Dependence has been constructed: External diffusion: -ln(1-F) = f(t) (2) Internal diffusion: F = f (t1/2) (3) where F = qt/qe is the degree of completion of the adsorption process, in which qt and qe are the adsorption capacity of sorbates onto the composite at the time t (hours (h)) and at equilibrium, respectively. It is known that if the correlation coefficient (R2 ) is closely related to dependencies, then the diffusional kinetics predominates over the limiting stage of those sorption process [14]. The results of the experimental data showed in Table 1. It can be seen that the correlation coefficient (R2 ) for both models are quite satisfactory. This suggests that the adsorption process of MB, CR, and TA onto magnetic composite sorbent were controlled by a mixed-diffusion model. To clarify the mechanisms that control the adsorption rate of multistage process we used the intraparticle diffusion model [15], which can be formulated as follows: 1/2 (4) t id q k t C where qt (mmol/g) is the adsorption capacity, kid (mmol.g-1 .h-1/2) is the rate constant of intraparticle diffusion and C (mmol/g) is the intercept. From Figure 1 can be seen that three continuous adsorption stages of MB, CR and TA could occur. The first stage characterized for the diffusion of MB, CR, and TA from the solution phase through the diffusion layer outside to the surface of the magnetic composite (external diffusion) [15]. The second stage refers to the diffusion of the MB, CR, and TA from surface of the magnetic composite to the adsorption centers (internal diffusion). The third stage was indicated to process of the formation bonds between the sorbates and the functional groups of the Fe3O4/PVA/APSCGs sorbent [16]. 2 BIO Web of Conferences 30, 02008 (2021) https://doi.org/10.1051/bioconf/20213002008 ILS 2020

Table 1. Parameters Of Diffusion Models For Adsorption Of mb, cr and ta Onto Fe3o4/pva/apscgs Sorbent Sorbate Co (mmol/l) Internal diffusion External diffusion Kid (mmol g1h 1/2) R2 R2 MB 0,15 0,419 0,983 0,990 0,30 0,435 0,972 0,969 CR 0,07 0,305 0,978 0,981 0,14 0,320 0,987 0,996 TA 0,03 0,262 0,992 0,993 0,06 0,274 0,985 0,970 To study the adsorption kinetics for MB, CR, and TA from aqueous solutions on the surface of magnetic composite sorbent we used the pseudo-first order model and pseudo-second order model and written as follow [17]: The pseudo-first order model: 1 ln(q ) lnq e t e q k t (5) The pseudo-second order model: 2 2 1 t e e t t q k q q (6) where qe (mmol/g) is the amount of adsorbed sorbates at equilibrium, qt (mmol/g) is the amount of adsorbed sorbates at time t, k1 (h−1) and k2 (g.mmol−1h −1) are the rate constants for the first order model and second order model, respectively. The results of the analysis parameters of the experimental data models are presented in Table 2. It is obvious that the pseudo-second order model described better the sorbates adsorption process onto magnetic composite sorbent because of its correlation coefficient (R2 ) higher than the pseudo-first order model, and in all initial concentrations of sorbates, the calculated values qe of the pseudo-second order model have a better similar with the experimental values (qe, exp). From the data above it can be concluded that the adsorption process of sorbates MB, CR and TA onto Fe3O4/PVA/APSCGs sorbent not only involves pore diffusion processes but also includes the formation of the interactions of sorbates with the functional groups of the sorbents. Adsorption thermodynamics. Adsorption thermodynamic parameters were calculated using Langmuir constant (KL) from constructing the adsorption isotherms at different temperatures 298-318 K. The linear Langmuir adsorption isotherms are described by the following equations [18]: 1 (7) . e e e m L m C C q q K q where Ce (mmol/L) is the equilibrium concentration of sorbates; qe (mmol/g) is amount of adsorbed sorbates onto the magnetic composite at equilibrium; qm (mmol/g) is the maximum adsorption capacity, KL (L/mmol) is Langmuir constant. Results (Table 4) showed that the adsorption isotherms of studied sorbates onto Fe3O4/PVA/APSCGs sorbent have a high adsorption capacity and increase with growth temperatures [19]. Comparison with many other common sorbents can be seen that Fe3O4/PVA/APSCGs sorbent have relatively high adsorption capacity among these adsorbents (Table 3). More importantly, the utilization of Fe3O4/PVA/APSCGs sorbent has a huge advantage of low cost due to the abundant resource of spent coffee grounds and sorbent after adsorption process can be easy for separating and regenerating from aqueous solution using an external magnet. The thermodynamic parameters such as enthalpy change (ΔH, kJ.mol-1 ) and entropy change (ΔS, J.K1 .mol-1 ) for the studied various temperatures were calculated using the Van't Hoff equation (8) and Gibbs free energy change (ΔG, kJ.mol-1 ) by the equation (9) [20]: (8) S H lnK R RT G RTlnK (9) where K is the equilibrium constant, K was calculated as dimensionless by multiplying it by 55.5 (number of moles of water per liter of solution), then 3 55.5 10 K K L (10), R is the universal gas constant (8.314 J.mol-1K-1 ); T is the temperature (K). Thermodynamic parameters obtained are shown in Table 5. From the data presented in Table 5, it was evident that adsorption of all studied sorbates was endothermic since the value of ∆H is positive. Similar results for endothermic adsorption were also observed on adsorption on chitosan [21], bentonite [12], alkaline pretreated spent coffee grounds [22]. The positive value of ΔS corresponding to the randomness rising at the solid–solution interface during the adsorption process [22]. In this study, the negative ΔG values indicated that adsorption sorbates onto the magnetic composite sorbent was spontaneous and adsorption capacity increased at higher temperatures. Fig. 1. Multistage process of qt at t1/2 for MB (0.15 mmol/l), CR (0.07 mmol/l) and TA (0.03 mmol/l) adsorption at 298 K onto Fe3O4/PVA/APSCGs sorbent Thus, according to the results of adsorption kinetic and thermodynamic studies, one might conclude that the mechanism for removal of the studied sorbates by adsorption onto magnetic composite sorbent Fe3O4/PVA/APSCGs may be assumed both physisorption (electrostatic interaction, internal and external pore diffusion and chemisorption (involve charge sharing or transfer from the organic molecules to the functional groups of sorbent surface to form a coordinate type of chemical bond. 3 BIO Web of Conferences 30, 02008 (2021) https://doi.org/10.1051/bioconf/20213002008 ILS 2020

Table 2. Kinetic parameters for adsorption of mb, cr And ta Onto Fe3o4/pva/apscgs Sorbent Sorbate Co (mmol/l) qe exp (mmol/g) Pseudo-first order model External diffusion k1 (h-1 ) qe (mmol/g) R2 k1 (gmmol1h -1 ) Qe (mmol/g) R2 MB 0,15 0,070 0,44 0,086 0,990 10,39 0,072 0,998 0,30 0,128 0,40 0,175 0,968 03,93 0,133 0,997 CR 0,07 0,022 0,22 0,018 0,980 20,46 0,023 0,999 0,14 0,041 0,29 0,037 0,996 16,07 0,042 0,999 TA 0,03 0,009 0,16 0,007 0,993 38,88 0,009 0,999 0,06 0,017 0,24 0,014 0,970 35,24 0,018 0,999 Table 3. Comparison Of qm Value Of Different Sorbents For mb, cr, ta Adsorption Sorbent Sorbate Adsorption conditions qm, (mmol/g) References Fe3O4/PVA/APSCGs MB pH 9, 25° C, 24 h 0,369 CR pH 4, 25° C, 24 h 0,088 In present study TA pH 5, 25° C, 24 h 0,066 Spent coffee grounds MB pH 5, 25° C, 12 h 0,059 [21] Magnetically modified coffee silverskin MB pH 6, 20° C, 6 h 1,738 [8] Magnetically modified spent coffee grounds CR pH 4, 25° C, 3 h 0,014 [9] Zeolite SMZ-CBC TA pH 5,5 25° C, 24 h 0,065 [22] Nano sorbent Fe3O4@SiO2-NH2 TA pH 6, 25° C, 24 h 0,08 [4] Table 4. Langmuir Isotherm Parameters For mb, cr and ta Adsorption Onto fe3o4/pva/apscgs Sorbent Sorbate T(K) Langmuir model Kl (L/mmol) qmax (mmol/g) R2 MB 298 11,31 0,396 0,987 308 20,29 0,613 0,995 318 23,96 0,711 0,996 CR 298 13,97 0,088 0,985 308 15,53 0,108 0,997 318 25,55 0,112 0,993 TA 298 16,08 0,066 0,987 308 19,32 0,082 0,993 318 23,60 0,084 0,994 Table 5. Thermodynamic Parameters Adsorption mb, cr and ta Onto Fe3o4/pva/apscgs Sorbent Sorbate T(K) ΔG ΔH ΔS MB 298 -33,07 308 -35,68 29,76 221.37 318 -37,28 CR 298 -33,60 308 -35,00 18,75 175,28 318 -37,12 TA 298 -33,95 15,09 164,51 4 Conclusion The composite sorbent obtained from alkaline pretreated spent coffee grounds and the synthetic magnetite has a high sorption capacity towards sorbates MB, CR, and TA. Adsorption of sorbates was controlled by a mixed diffusion model and pseudo-second order model. Detailed analysis of qe dependence on t 1/2 allowed to distinguish three separate stages of the process. The results of determination of thermodynamic parameters ΔG, ΔH and ΔS showed that the process of adsorption of sorbates was shown to be an endothermic one and adsorption mechanism may be a combination of both physisorption and chemisorption. 4 BIO Web of Conferences 30, 02008 (2021) https://doi.org/10.1051/bioconf/20213002008 ILS 2020

Acknowledgment This work was supported by Graduate University of Science and Technology under grant number GUST.STS.ĐT2017-KHVL02. References 1. M. T. Amin, a a Alazba, and U. Manzoor, “A review on removal of pollutants from water / wastewater using different types of nanomaterials,” 2014 (2014) 2. X. He, K. B. Male, P. N. Nesterenko, D. Brabazon, B. Paull, and J. H. T. Luong, ACS Appl. Mater. Interfaces, 5(17), 8796–8804 (2013) 3. .S. Munagapati and D. S. Kim, J. Mol. Liq., 220, 540–548 (2016) 4. J. Wang, C. Zheng, S. Ding, H. Ma, and Y. Ji, Desalination, 273, 285–291 (2011) 5. D. Mohan, H. Kumar, A. Sarswat, M. AlexandreFranco, and C. U. Pittman, Chem. Eng. J., 236,. 513–528 (2014) 6. I. Šafařík, K. Nymburská, and M. Šafaříková, J. Chem. Technol. Biotechnol., 69, 1, 1–4 (1997) 7. M. H. Baek, C. O. Ijagbemi, S. J. O, and D. S. Kim, J. Hazard. Mater., 176, , 820–828 (2010) 8. A. Zuorro, A. Di Battista, and R. Lavecchia, Chem. Eng. Trans., 35, 1375–1380 (2013). 9. I. Safarik, K. Horska, B. Svobodova, and M. Safarikova, Eur. Food Res. Technol., 234(2), 345– 350 (2012) 10. I. Safarik, K. Horska, K. Pospiskova, Z. Maderova, and M. Safarikova, IEEE Trans. Magn., 49(1), 213– 218 (2013) 11. Kannan and M. M. Sundaram, “Kinetics and mechanism of removal of methylene blue by adsorption on various carbons—a comparative study,” Dye. Pigment., 51(1), pp. 25–40 (2001) 12. S. Hong, C. Wen, J. He, F. Gan, and Y. S. Ho, J. Hazard. Mater., 167, , 630–633 (2009) 13. C. Sarici-Ozdemir, Physicochem. Probl. Miner. Process., 48(2), 441–454 (2012) 14. O. V. Perlova, V. F. Sazonova, N. A. Perlova, and N. A. Yaroshenko, Russ. J. Phys. Chem. A, 88(6), 1012–1016 (2014) 15. E. Lorenc-Grabowska, G. Gryglewicz, and M. A. Diez, “Kinetics and equilibrium study of phenol adsorption on nitrogen-enriched activated carbons,” Fuel, 114, pp. 235–243 (2013) 16. T. Feng and L. Xu, Adv. Mater. Res., 690–693, 438–441 (2013) 17. Y. Lei, J.-J. Guan, W. Chen, Q.-F. Ke, C.-Q. Zhang, and Y.-P. Guo, RSC Adv., 5(32), 25462–25470 (2015) 18. P. Hou, C. Shi, L. Wu, and X. Hou, Microchem. J., 128, 218–225 (2016) 19. J. He, S. Hong, L. Zhang, F. Gan, and Y. S. Ho, Fresenius Environ. Bull., 19(11A), 2651–2656 (2010) 20. A. Ramesh, D. J. Lee, and J. W. C. Wong, J. Colloid Interface Sci., 291(2) 588–592, (2005) 21. S. Banerjee and M. C. Chattopadhyaya, Arab. J. Chem., 10, S1629–S1638 (2017) 22. Y. Dai, D. Zhang, and K. Zhang, J. Taiwan Inst. Chem. Eng., 68, 232–238 (2016) 23. P. Llewellyn, Adsorption by Ordered Mesoporous Materials, 2nd ed. Elsevier Ltd. (2013) 24. C. C. Rodrigues, D. Moraes, and U. F. De, Technology, 2(1), 1013–1022 (2002) 25. A. Zarrouk, B. Hammouti, H. Zarrok, and M. Messali, “Temperature Effect , Activation Energies and Thermodynamic Adsorption Studies of LCysteine Methyl Ester Hydrochloride As Copper Corrosion Inhibitor In Nitric Acid 2M,” 6, pp. 6261–6274 (2011) 26. H. Chen, J. Zhao, and G. Dai, J. Hazard. Mater., 186, 1320–1327 (2011) 27. D. C. Emeniru, O. D. Onukwuli, P. Douyewodu, and B. I. Okoro, “The Equilibrium and Thermodynamics of Methylene Blue Uptake onto Ekowe Clay ; Influence of Acid Activation and Calcination,” 5, 17–25 (2015) 5 BIO Web of Conferences 30, 02008 (2021) https://doi.org/10.1051/bioconf/20213002008 ILS 2020

Simultaneous thermal analysis of mineral fertilizers, purchased in Almaty Ilona Matveyeva, Nurgul Nursapina, Askar Bakhadur, Sholpan Nazarkulova, Balnur Shynybek,and Oksana Ponomarenko* Dept. of General and Inorganic chemistry al- Farabi Kazakh National University, Almaty, Kazakhstan Abstract. Increased demand for agricultural products leads to soil depletion and increased use of mineral and organo-mineral fertilizers. Mineral fertilizers used in agriculture may contain contaminators such as heavy metals or radionuclides that can migrate and accumulate in plants. Although migration and accumulation abilities directly depend on species in which they are presented. Determination of species of heavy metals and radionuclides can be done by sequential extraction technique, which takes long time and a lot of reactants. Preliminary evaluation can be done on the basis of data of simultaneous thermal analysis. In the present study the simultaneous thermal analysis was used for investigation of mineral fertilizers, purchased in Almaty. “Fasko” with ammonia nitrate and “Bujskie udobreniya” fertilizers contain water-soluble fractions and “Ljubo zeleno” and “Fertika” contain organic soluble fractions. 1 Introduction Kazakhstan is a developing country with a growing population and evolving economics [1]. Agriculture plays a significant role in the development of economics of the country. Mentioned economics sector is developing all around Kazakhstan and, especially, in southern regions of Kazakhstan due to better climate conditions and access to water resources. Moreover, South Kazakhstan is the region with biggest population density in the country, two of three megapolises, i.e. Shymkent and Almaty, are situated in the south. Therefore, the tendency of growth of production rates in agricultural sector can be seen annually. Growing food demand leads to soil depletion and in order to solve these problem mineral and organo-mineral fertilizers are widely used. In addition to that, it can be said that soils of South Kazakhstan require regular special treatment with fertilizing agents due to soil types [2]. The biggest issues in application of fertilizers are use of fertilizers above normal concentrations and the contamination of mineral fertilizers with toxicants. Mineral fertilizers may contain radionuclides or heavy metals incorporated in natural apatite, which is the origin of phosphate containing fertilizers, or potassium containing fertilizers may contain K-40, radioactive isotope, above normal concentration. Phosphorus containing fertilizers are more probable to contain uranium and thorium in their content and the concentrations may reach up to 660 mg/kg for U and 220 mg/kg for Th [3]. Species of contaminators is a cause for concern, because it determines migration ability of toxicant and consequently probability of their migration into edible parts of plants [4]. In order to predict the species of contaminators, simultaneous thermal analysis (STA) can be used as fast and simple method. 2 Experimental Seven samples of mineral fertilizers were purchased in Almaty, namely, “Fasko” granulated superphosphate, “Fertika” organo-mineral fertilizing mixture for vegetables, “Bujskie udobreniya” monopotassium phosphate, “Fasko” fertilizer including ammonia nitrate, “Ljubo zeleno” fertilizer, “Ogorodnik” double superphosphate, “Ogorodnik” phosphate fertilizer. Contents of analyzed fertilizers samples given by producers are presented in Table 1. Sample preparation included the homogenization of samples with pestle and mortar crushing. Samples were placed in corundum crucibles and analyzed on NETZSCH STA 449 F3A-0372- M with NETZSCH Proteus software. The identical empty corundum crucible was put with the analyzing sample as a reference. The temperature grew from 30 to 800°C. The heating rate was equal to 20° K/ min. The atmosphere of the analysis was nitrogen gas with purity of 99.99 %. 3 Results and discussion Seven thermogravimetric differential scanning calorimetry (TG/DSC) curves were obtained as a result of simultaneous thermal analysis. TG/DSC curves are able to characterize the thermal stability of analyzed fertilizers, i.e. they can show decomposition or ignition processes and loss of mass on each step. On Fig. 1 that corresponds to “Fasko” granulated superphosphate it was seen that decomposition starts at 115° C and at that step absorbed water was evaporated *Corresponding author: [email protected] © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 30, 02009 (2021) https://doi.org/10.1051/bioconf/20213002009 ILS 2020

with weight loss of 0.80 %. Gradual mass loss indicates decomposition process on temperatures 130-350 °C. Endothermic process was indicated at temperature range of 440-800 °C with mass loss of 30.31 %. Total mass loss during the analysis was equal to 44.77 %. In Fig. 2 TG/DSC curve for “Fertika” organomineral fertilizing mixture for vegetables is shown, total mass loss in this analysis was equal to 49.14%. Gradual mass loss of 1.88 % at temperatures 90-110 °C indicated evaporation of absorbed water. Exothermic ignition process was presented at range of 200 to 280 °C with massive and severe mass loss of 23.71%, which indicated organic matter ignition. From 290 to 800 °C gradual mass loss was presented with endothermic process at 630- 680 °C which indicated decomposition of inorganic components. “Buiskie udobreniya” monopotassium phosphate TG/DSC curve is shown in Fig. 3. The sample was undergoing endothermic process; total mass change was equal to 12.60 %. Decomposition of sample constituents started at 200 to 340 °C with mass loss of 7.69 %. Weight loss at range from 330 to 380 °C at that step was equal to 4.91 % and corresponded to endothermic process, which was evaporation of crystallised water, further the mass stayed constant with endothermic melting process at 450-470 °C. “Fasko” fertilizer with ammonia nitrate is presented in Fig. 4. Endothermic process was registered from the very beginning of analysis 40-200 °C which indicated melting processes without mass change. At range of temperature from 275 to 360 °C main mass loss observed which was equal to 97.75 %. It was related to decomposition of main component of the fertilizerammonia nitrate according to the (1). Endothermic process – melting, was registered at 470-480 °C. 2NH4NO3 = 2N2 + 4H2O + O2 (1) Fig. 5 shows TG/DSC curve of “Ljubo zeleno” fertilizer with insignificant mass loss of 1.61 % with respective endothermic effect on differential scanning calorimetry (DSC) in range of temperatures from 60 to 165 °C which identified as dehydration process. Upon further heating up to 300 °C organic matter exothermic process of ignition was seen with mass loss of 17.21 %. From 300 to 800 °C mass loss was equal to 12.79 %, which may indicate decomposition of inorganic matter. Total mass loss was equal to 31.61 %. In Fig. 6 “Ogorodnik” double superphosphate TG/DSC curve is presented. At 100-110 °C absorbed water evaporated accompanied with 2.59 % mass loss. Heating up to 260 °C led to crystallised water splitting and following loss of 11.79 % of mass. Gradual mass loss was seen up to 700 °C and at temperature range of 700-800 °C severe mass loss was indicated with endo effect. Total mass loss was equal to 34.55 %. “Ogorodnik” phosphate fertilizer TG/DSC curve is shown in Fig. 7, where multiple decomposition processes were accompanied with gradual mass loss at temperature range of 30 to 390 degrees. From 610 to 800° C staggered endo effect registered with corresponding mass loss. The total mass loss was equal to 20.92 %. Table 1. Content of components, reported by producer Fertilizer N, % P2O5, % Ca, % MgO, % K2O, % “Fasko” granulated superphosphate 9 30 - - - “Fertika” organo-mineral fertilizing mixture for vegetables - 5 - - 8 “Bujskie udobreniya” monopotassium phosphate - 50 - - 33 “Fasko” fertilizer including ammonia nitrate 33 - - - - “Ljubo zeleno” fertilizer 10 12 - - 15 “Ogorodnik” double superphosphate 5 20 - - - “Ogorodnik” phosphate fertilizer 8 20 20 0.5 - Fig. 1. “Fasko” granulated superphosphate TG/DSC curve Fig. 2. “Fertika” organo-mineral fertilizing mixture for vegetables TG/DSC curve 2 BIO Web of Conferences 30, 02009 (2021) https://doi.org/10.1051/bioconf/20213002009 ILS 2020

Fig. 3. “Bujskie udobreniya” monopotassium phosphate TG/DSC curve Fig. 4. “Fasko” fertilizer with ammonia nitrate TG/DSC curve Fig. 5. “Ljubo zeleno” fertilizer TG/DSC curve 4 Conclusion High “Fasko” granulated superphosphate, “Ogorodnik” double superphosphate and “Ogorodnik” phosphate fertilizer contains big amounts of water both crystallised and absorbed. On each sample listed above the decomposition processes are registered at temperature ranges from 400 to 800o C. Five of seven fertilizer samples undergo endothermic processes during the heating, exception is strong exothermic process that observed in “Fertika” organo-mineral fertilizing mixture for vegetables, which indicates large amounts of organic matter in content. Less severe exothermic effect seen in “Ljubo zeleno” fertilizer, which also specify organic substances in content. The organic matter is soluble in organic solvents; thus, migration ability will be high and mobile fraction is organic. “Bujskie udobreniya” monopotassium phosphate and “Fasko” fertilizer with ammonia nitrate are containing inorganic water-soluble compounds, which allow to predict high potential of migration ability of intoxicants in that water-soluble species. Fig. 6. “Ogorodnik” double superphosphate TG/DSC curve Fig. 7. “Ogorodnik” phosphate fertilizer TG/DSC curve References 1. Rakhmetova R., Abenova K., Procedia Economics and Finance, 5, 631-636 (2013) 2. Klebanovich N. V., Efimova I. A., Prokopovich S. ucheb. materialy dlja studentov spec. 1-56 02 02 «Geoinformacionnye sistemy» (2016) 3. Vogel, C., Hoffmann, M. C., Taube, M. C., Krüger, O., Baran, R., Adam, C., Journal of hazardous materials, 382, 121100 (2020) 4. Kumar A., Chauhan R. P. “Journal of Radiation Research and Applied Sciences, 7, 454-458 (2014) 3 BIO Web of Conferences 30, 02009 (2021) https://doi.org/10.1051/bioconf/20213002009 ILS 2020