The paper presents data on the actual issue ofthe usage of the microalgae Chlorella sorokiniana in the biotechnological field. Its vitamin and amino acid contents, which arehigher than in soy, enriches its nutritional value.This article also provides information on the utilization of chlorella as an enrichment supplement to develop a modern Life Support Systemfor manned spacecraft. Based on the data collected from various bibliographical studies, it is recommended to take into account the established positive effect of light exposure on the microalgae for the production of astaxanthin, as well as, to vary the composition of the nutrient medium in order to obtain a dry microalgae biomass with a fixed lipid, protein and starch content. The influence of various physical factors on the specificity of biochemical processes in the cell and the variation in the composition of dry biomass in the cultivation of Chlorella sorokiniana was studied. Experimental results of the application ofa red laser (output power 1.6 mW, wavelength 0.63 µm), the exposure to daylight (intensity 2800 Lux), infrared (power 250 W, intensity 14100 Lux) and ultraviolet (wavelength 280-315 nm) radiations of the microalgalsamples are presented. The most significant concentrationsof protein compounds (46.0% and 48.4% of dry biomass) were obtained after the exposure to daylightand to infrared radiation. In the last case, the fatty acid composition of the sample was represented mainly by unsaturated acids (77% by weight). The biomass of C. sorokiniana cultivated under the influence of daylightshowed an increased content of chlorophylls a (19.3 mg/g), chlorophyll b (7.1 mg/g) and of total carotenoids (2.8 mg/g). Under the action of ultraviolet light, the quantity of saccharides increased (up to 430 mg/g).The data obtained enables to select optimal cultivation conditions of Chlorella sorokinianain order to obtain a biomass with a given composition and properties.
In the present article we introduce application areas of Сhlorella sorokiniana microalgae biomass for national economy (feed and biologically active additives, etc). Here it is shown that thermal and chemical modification of plant material waste might result in obtaining of highly-efficient materials for water purification. Major stages of waste-free technology of microalga processing with further extraction of valuable lipids and obtaining of sorption materials are schematically shown. We have determined fatty-acid content of lipid fraction (77 mg/g), obtained by Soxhlet method from lyophilized microalga biomass. It was revealed, that it includes 83.7% of unsaturated fatty acids (generally, С18:1, С18:2, С18:3), whereas saturated fatty acids are mostly presented by С16 – С20 family. In lyophilized biomass we discovered α-linolenoic acid (Omega-3, 28.3%), which is one of the most valuable biologically active compounds, required for full-value human life and activities. Microstructure analysis of residual biomass of C. sorokiniana microalgae has shown pore surface, formed by destroyed cells. In the course of studying the sorption properties of residual biomass with the use of initial and final concentration parameters, the efficiency of purification of model water from Fe3+ ions (47.5%) was evaluated, which indicates the need to modify the sorption properties of biomass. It has been established that the degree of wastewater purification containing iron (III) compounds can be significantly increased (by 1.8 times) by forming from the residual biomass granular materials with additional introduction of chitosan in the composition, which using as a binder and a modifying additive (mass ratio 4:1).
The phase composition of natural pink clay was studied and influence of sorption properties on purification of mustard oil was investigated. The clay was activated by treatment with oxalic acid and sodium carbonate before using. The acid-base activation of natural material was shown to promote the creation of the new centers on its surface. The new materials demonstrated a positive effect on the oil purification process from fatty acids, peroxide compounds and no effect on the concentrations of carotenoids.
I In the work there were studied the regularities of extracting copper (II) and lead (II) cations from aqueous solutions with the help of natural sorbents from the Astrakhan region such as the marl of the Baskunchak deposit, the Kamennyy yar deposit and the clay of the Volzhsky deposit. A comparative study was made of the applicability of the adsorption models of Langmuir, Freindlich, Temkin, and Dubinin-Radushkevich to describe the experimental adsorption isotherms of these cations on the surface of aluminosilicates. The constants and parameters of the equations corresponding to these models are determined. A comparison of the regression coefficients shows that the Temkin model is suitable for describing the adsorption equilibria in the "M2+ -clay" systems. The Freundlich model most adequately describes the experimental data on adsorption in the "M2+ -marl/opoka" systems, which reveals the heterogeneous surface of both of these materials with a large number of energetically dissimilar active centers. The regression coefficients found in this case by the Langmuir model are small; the boundary conditions for the description of systems with a monomolecular coating are not observed. The Dubinin-Radushkevich model was also used to describe the process of concentrating lead (II) compounds on the marl surface of the Baskunchak deposit and the Kamennyy Yar deposit. The calculated values of the free energy of adsorption were 11.2 (opoka) and 4.17 kJ/mol (marl). The process of fixing lead cations on these natural sorbents in the Astrakhan region proceeds according to the ion-exchange mechanism. The adsorption activity of Cu2+, Pb2+ ions on the surface of sorbents is confirmed by the calculated values of Gibbs energy and entropy. The endothermic nature of the processes taking place with the participation of the clay of the Volzhsky deposit and the Kamennyy Yar deposit is explained by the considerable energy expenditure for the dehydration of the surface groups of sorbents. For citation: Dzhigola L.A., Sadomtseva O.S., Shakirova V.V., Kargina K.V., Syutova E.A., Razgovorov P.B., Nagornov R.S. Application of adsorption models for description of equilibria in systems cations of copper (II) and lead (II) – natural materials of Astrakhan region. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 105-112
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