Том 10, № 1 (2020)
- Жылы: 2020
- Мақалалар: 19
- URL: https://journals.rcsi.science/2227-2925/issue/view/19789
Бүкіл шығарылым
Chemical Sciences
Aspects of lithium tri- and tetraborate synthesis in the subsolidus region
Аннотация
The present work is focused at studying the transformation patterns for the crystalline structure of phases formed during the synthesis of polycrystalline lithium tri- and tetraborate. In the field of lithium triborate (LiB3O5) and tetraborate (Li2B4O7) of the Li2O – B2O3 system, LiB3O5 and Li2B4O7 polycrystalline powders were synthesised. In terms of precursors, lithium carbonate (Li2CO3) and boric acid (H3BO3) were selected. Two synthesis methods were tested including precipitation from solution and solid-phase synthesis. As a result, the direct sintering of a mechanically-grinded stoichiometric precursor mixture is shown to be the optimal method for crystallising LiB3O5 and Li2B4O7. The crystallisation patterns of lithium borates were studied in a temperature range of 500-850 °C with sampling carried out every 50 °C. Individual phase portraits were established presenting a set of process character-istics depending on the level of substance particle organisation and subsolidus crystallisation from the initial reagent mixture of lithium tri- and tetraborate at the phase, local and structural levels. In a lithium triborate stoichiometric mixture, the maximum conversion of crystalline phases is observed in the region of 500–600 °C, while, for lithium tetraborate, the temperature maximum is in the range of 600–700 °C. The sequence of phase transformations re-mains almost unchanged and occurs according to the following scheme: starting reagents > intermediate metastable phases > final borates. The local level of phase portraits characterises the interaction of coordination polyhedra forming the crystal lattice of the studied phases. Solid-phase synthesis of crystalline LiB3O5 from the Li2CO3 and H3BO3 takes place as a result of (BO3)3- → (B3O7)5- transition with the (BO3)3- → (B4O9)6- scheme realised in obtaining Li2B4O7. At the crystal structure level, such transitions correspond to transformations of the monoclinic lattice of the Li2CO3 and H3BO3 primary phases into the LiB3O5 and Li2B4O7 rhombic and tetragonal structure, respectively. In this case, an intermediate step of this transformation consists in formation of the LiBO2 trigonal chain metaborate and metastable Li2B8O13.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):6-13
6-13
Vinylidene chloride- and styrene-based sulphonate-containing copolymers
Аннотация
Bare polyvinyl chloride (PVC) and polyvinylidene chloride are not commercially used due to their high softening point (185–200 ºС) and the absence of a suitable solvent for obtaining coatings (films) from their solutions. Therefore, vinyl chloride and vinylidene chloride are mainly applied in the production of copolymers having a lower pour point and better solubility as compared to homopolymers. Polymer materials based on copolymers of vinyl chloride and vinylidene chloride are widely used in a number of industrial applications. Recent research has been focused on monomer rafting onto a vinyl chloride and vinylidene chloride copolymer base by the formation of free radicals as a result of the transfer reaction of a chlorine atom to an initiating agent followed by sulphonation. Membranes obtained from solutions of grafted copolymers possess high proton conductivity values resulting in their perspective application for fuel cell manufacture. In order to obtain such membranes, it is necessary to carry out studies on the synthesis of vinylidene chloride copolymers and the substitution of chlorine atoms with sulphonic acid groups in these copolymers. In the framework of this work, vinylidene chloride and styrene copolymers were obtained by radical copolymerisation. The substitution of chlorine atoms by sulphonic acid groups in the synthesised copolymer was studied. The composition and structure of the copolymers were characterised using elemental analysis and IR spectroscopy data. The co-polymerisation values indicate a greater reactivity of styrene in comparison with vinylidene chloride. The interaction of a vinylidene chloride copolymer and styrene with sodium sulphide is accompanied by dehydrochlorination of vinylidene chloride units. The spatial modified copolymer structures are generated by double bonds formed as a result of elimination in a macromolecule.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):14-20
14-20
Acid-base properties of silicon-containing compounds isolated from horsetails (Equisetum Equisetaceae)
Аннотация
The results of a study into the acid-base surface properties of four silicon-containing ash samples obtained from the above-ground part of the field horsetail plant species (E. arvense L.) are presented. The samples were derived according to various schemes, comprising oxidative roasting both with and without preliminary treatments involving water and solutions of hydrochloric acid having a concentration of 0.1 and 1.0 mol/l. It was shown that the content of silicon dioxide in the samples varies from 33 to 98 % depending on the conditions of processing of raw materials. Preliminary processing of the raw material with an acid solution prior to roasting results in the formation of ash having a high silicon oxide content. The main impurity elements are calcium, potassium, magnesium, aluminum and iron. Samples prepared without preliminary treatment, as well as those treated with water, are characterised by a large amount of alkaline earth metal- and potassium oxides. A comparative characteristic of the surface condition of the obtained ash samples is given using pH measurements and the Hammett acidity function method. The pH measurements allow the integral acidity of the surface to be evaluated, while the Hammett method, based on the selective adsorption of acid-base indicators, is used to study the distribution of surface centres by acid-base properties. The pH values of the aqueous suspensions of neutral, alkaline or acidic samples are determined depending on the plant tissue processing scheme. It was found that the surface of the samples is characterised by the presence of Lewis acid- (pKa +16.8), Brønsted basic- (pKa +7.15; +9.45) and acid- (pKa +2.5) active sites, the amount of which is determined by the composition of the samples. The high content of Lewis acid sites in the ash is associated with silicon atoms. The number of Bronsted sites depends on the horsetail treatment scheme. On the surface of samples obtained by oxidative roasting and those pretreated with water, the number of Brønsted active sites at pKa +2.5 and pKa +9.45 is higher compared to ash isolated following hydrolysis with hydrochloric acid. A comparative characteristic of the distribution curves of acid-base centres of silicon-containing ash samples obtained from the above-ground parts of field horsetail and rice straw is given, indicating their similarity.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):21-28
21-28
Regression models of zinc ion adsorption from aqueous solutions on zeolite from Kholinski deposit, modified with with a sulphur-containing polymer
Аннотация
This article presents regression analysis results of experimental data obtained from a study of the sorption of zinc ions from standardised aqueous solutions using zeolite (clinoptilolite type, Kholinski deposit) modified with a sulphur-containing polymer. Differences in the IR spectra of the modified zeolite were registered before and after sorption of Zn2+ from an aqueous solution. The effect of the following technological parameters on the adsorption capacity of the modified zeolite was studied: pH, initial concentration of Zn ions in solution, temperature and sorption time of the studied zinc ion extraction. It was shown that the adsorption activity of the modified zeolite of the Kholinsky deposit cannot be approximated by the classical Freundlich and Langmuir equations, since the Zn (II) ion sorption mechanism is complexly coordinated. It was found that the Freundlich equation describes only 40% of the experimental data on the adsorption of zinc ions by a modified zeolite, while the Langmuir equation describes 71%. Accordingly, regression analysis was used to process the measurement results. The found nonlinear regression models reliably describe the observed patterns of sorption and desorption. Kinetic curves of the solution at different temperature conditions are described by exponential models. Adsorption activity toward zinc ions of activated carbon-, as well as natural- and modified-zeolite sorbents was studied. The comparison revealed significant advantages on the part of the modified zeolite: modification of the zeolite surface with a sulphur-containing polymer made it possible to increase its sorption ability by 4.5 times compared to natural zeolite and 9 times compared to activated carbon.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):29-38
29-38
Physico-chemical biology
Methods for improving the preservation of natural antioxidants in meat products
Аннотация
The article presents the results of a study into methods for increasing the preservation of polyphenolic compounds in the composition of meat products in terms of expanding product ranges and improving the functional effectiveness of foods. Various quality indicators of a dry extract of lingonberry (DLE) grown in Transbaikal regions were studied. The extract, obtained from lingonberry husks, was characterised by a mass fraction of moisture of 4.52 % and acidity of 5.6 %, having a burgundy colour, a sweet and sour taste and characteristic lingonberry aroma, as well as a free-flowing powder consistency. The DLE was established to have a high total antioxidant content of 382.5 mg / g. With the introduction of 0.2 % DLE into a meat steak recipe, the total content of antioxidants following thermal processing in the final product decreased by 18.7%. In order to increase the antioxidant activity and corresponding preservative effectiveness in the ready-to-serve products, various methods for increasing bioavailability, including sorption and encapsulation of biologically active substances of DLE were used. An offal paste based on beef honeycomb tripe, lung and diaphragm was developed for sorption of DLE polyphenols. The matrix consisted of collagen proteins of offal connective tissue having high sorption ability; moreover, fine grinding of by-products into a homogeneous consistency provided good conditions for the immobilisation of polyphenols. The results demonstrate that the use of this method reduced the loss of antioxidants to 7.4 %. Next, the possibility of using an encapsulated form of DLE was considered. Liposomal forms of an extract dissolved in a buffer solution and water were developed. Soy lecithin was used as a liposome forming agent. The obtained data indicated that the introduction of the liposomal form of plant polyphenols contributed to the greater preservation of antioxidants. Specifically, when dissolving the dry lingonberry husks extract in water, the loss of antioxidants was 5.3 %, and when dissolved in a buffer solution, only 3.4 %.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):84-94
84-94
Isolation of the Inonotus obliquus chaga mushroom strain and intensification of a culture growth during solid-phase cultivation
Аннотация
The extracts from fungus Inonotus obliquus (Pers.:Fr.) Pilat (chaga), which have been widely used in medicine and cosmetics due to their high antioxidant properties, are in evergrowing demand currently. Since fungus natural resources are limited, the search for new highly productive Inonotus obliquus strains and the methods for its cultivation development with the high production ability of the main active component - melanin, are relevant. The aim of the present study was to isolate a new Inonotus obliquus strain from natural chaga, introduce it into a standard culture registered in an international database, as well as determine the optimal cultivation environment for the procurement of melanins with high antioxidant properties. A new strain of the fungus Inonotus obliquus SUB2092728 was isolated. For its growth, an agar nutrient medium was selected. It was shown that Inonotus obliquus SUB2092728 has a maximum growth rate of 2.18 mm/day in a glucose-potato medium with the onset of pigmentation on the 8th day of growth. The introduction of the hydrolysed lignin-containing drug Polyphepan into the environment made it possible to intensify the growth of the fungus and increase its growth rate up to 3.60 mm/day. It was established that the obtained melanins differ from the natural chaga melanin in terms of a lower degree of aromaticity and a higher degree of aliphaticity, as well as exhibiting antioxidant properties 16 % higher than natural melanin, making them suitable for use in the development of biologically active additives having antioxidant properties.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):95-106
95-106
Pilot submerged cultivation of Trichoderma asperellum RNCIM F-1323 micromycete
Аннотация
The study is aimed at developing a pilot industrial method for producing a biofungicide based on the fungus of Trichoderma genus. The cultivation was carried out by submerging in a pilot industrial bioreactor line with an inoculation bioreactor having a total volume of 10 litres and a working bioreactor with a total volume of 100 litres. Czapek’s modified nutrient medium was used with yeast extract and molasses replacing sucrose, g/L: molasses – 20; yeast extract – 7; NaNO3 – 2; K2HPO4 – 1; MgSO4 – 0.5; KCl – 0.5; FeSO4 – 0.01. Cultivation was carried out maintaining the following parameters: temperature – 27±0.5 ºС; culture medium mixing speed – 600 rpm; aeration intensity – 1 L of air per 1 L of culture medium per min. The inoculum was grown on a nutrient medium of a similar composition in rocking flasks with a total and a working volume of 750 and 100 mL, respectively. Inoculated flasks were incubated using an Innova 40R shaker incubator (New Brunswick, USA) at 200 rpm for 22–24 h until a dry biomass index of 6.5–7.5 g/L was achieved. Conidia concentration was calculated using a Goryaev camera. Liquid cultivation was selected due to its relatively short process time. In addition, unlike solid-phase, the submerged cultivation provides for the accumulation of numerous secondary metabolites having antagonistic activity against phytopathogens in the finished form of the preparation. The object of the study was the Trichoderma asperellum RNCIM F-1323 strain with antagonistic activity against many phytopathogens. From a technical and economic point of view, the culture transfer to an inoculation bioreactor in an amount of 5 % vol. was established to be justified as a result of the experiments. The effect of various time values for cultivation in inoculation bioreactor on the growth rate of micromycetes in a working bioreactor was studied. The optimal time for transfer to a working bioreactor was determined to be within 20–24 h. At the end of the cultivation process, the conidia concentration was equal to 1.9·108 conidia/mL.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):39-47
39-47
Full-genome sequencing of the Staphylococcus warneri strain isolated from oil-contaminated soil
Аннотация
Bacterial consortium bioremediation presents itself a promising approach to the treatment water, soil and the atmosphere for pollution by oil and its derivatives. In the territory of the Romashkinskoye oil field, Republic of Tatarstan, various decomposers were isolated from oil-contaminated black soil, including three that demonstrated oil resistance and ability to produce biosurfactants. The genome sequencing of the Staphylococcus warneri strain isolated in a consortium of decomposers was performed on the MiSeq Illumina plat-form. The average content of GC pairs in the genome comprised 32.7 %. Genome annotation was performed using the RAST server. The SEED viewer was applied for subsystem category distribution of predicted genes. The sequenced genome of Staphylococcus warneri strain was identified as containing 2535 protein coding sequences. The majority of annotated genes govern the synthesis of amino acids and their derivatives (255), carbohydrate (195) and protein metabolism (167), cofactors, vitamins, prosthetic groups and pigmented formations (87), nucleosides and nucleotides (78), fatty acid metabolism, lipids and isoprenoids (55), as well as DNA metabolism (68). The full-genome sequencing and genome annotation of the Staphylococcus warneri strain confirmed its hydrocarbon-oxidising properties. The yddN and yceB genes of uncharacterised proteins were identified as similar to alkanal monooxygenases likely to be involved in the biodegradation of alkanes. The three genes detected in this strain code the catechol-2,3-dioxygenase, fumarylacetoacetate hydrolase and salicylate-1-monooxygenase enzymes involved in the biodegradation of aromatic hydrocarbons. The obtained genome sequence data help to provide a better understanding of the process of hydrocarbon degradation (absorption) by the Staphylococcus warneri strain and its role in the bacterial consortium.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):48-55
48-55
Effect of cold helium plasma on the catalytic activity of certain erythrocyte dehydrogenases of rat blood
Аннотация
The work is aimed at clarifying the effect of cold helium plasma on the catalytic properties of lactate- and aldehyde dehydrogenase in rat blood erythrocytes. The effect was studied in 20 white Wistar rats. Upon completion of the full course of exposures (1 exposure per day for 5 days), blood samples were taken from all animals with subsequent erythrocyte isolation performed by standard differential centrifugation for assessing the activity of lactate dehydrogenase (LDH) and aldehyde dehydrogenase (AlDH). When assessing LDH activity, both direct and reverse reactions were considered. Gas flow microwave ionisation was applied to the synthesis of cold plasma using a special device developed at the Institute of Applied Physics, Russian Academy of Sciences. The plasma treatment was established to provide stimulation of LDH activity in both direct and reverse reactions. In the direct reaction, erythrocytic LDH activity in rats with plasma-treated skin almost doubled (94 %) against 48 % of activity growth in the reverse reaction. Rat blood erythrocyte AlDH tends to moderate inactivation, with catalytic properties observed to decrease by 13 %. Thus, treating the skin of healthy rats with cold helium plasma was demonstrated to stimulate the energy metabolism of blood cells, with moderate activity inhibition for AlDH presenting one of the detoxification enzymes. The nature of the observed shifts indicates their adaptability. In general, according to the obtained data, the modulation of free radical processes was confirmed to play a key role in the molecular-cellular mechanisms of the cold helium plasma action on the biological system.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):56-62
56-62
Restoring biocoenotic species composition in aerated structures following prolonged downtime
Аннотация
A study was carried out into the dynamics of species composition for immobilised sludge with inert brush filtering following prolonged bioreactor downtime. The experimental part was carried out using microscopic analysis. The start of a bioreactor with sludge adapted to wastewater provides a specified degree of purification within a stated period of time. The experiment was carried out in a physical bioreactor model presenting a transverse vertical section of an industrial bioreactor aerotank. The dynamic dependency of the quantitative increase in biocoenotic species composition during the recovery period is obtained. The dynamics of biocoenosis is determined by the example of ciliate vital activity. A mathematical expression for calculating the ciliate movement speed during biocoenosis recovery is obtained. In culturing the biocoenosis under aerobic conditions, the rate of mass change for immobilised sludge with brush filtering is presented. The application of bioreactors with immobilised sludge under brush filtering provides for the biological treatment of sewage through the creation of aerobic conditions and cyclic transfer of immobilised sludge to freely floating sludge using air medium bubble aeration. In ten days, the microorganism species composition increased to the initial 6 species having a physiological biocoenosis state characterised as satisfactory.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):77-83
77-83
Refractometry study of polymorphic transformations in animal fats and their blends
Аннотация
The aim of the work is to carrying out a comparative refractometry study of changes in the refractive index (nD) during consecutive heating-cooling processes for a series of fats obtained from domestic and wild terrestrial animals, birds, marine mammals and fish, as well as a vegetable oil sample of four groups classified by iodine number (IN). Within the framework of the study, an analysis of liquid and solid lipid blends was carried out according to the ratio of components (0-20-50-70-100 %). Optical refractive indices and IN were measured by an Abbemat WR/MW digital refractometer (Austria) at three different wavelengths (436.4, 589.3 and 657.2 nm) in a temperature range from 20 to 70 °C. On the nD = f (Т, °С) heating dependencies in the range of 30-45 °С for solid animal fats and vegetable oils, sharp bends were observed corresponding to the melting temperatures of α - and β1 crystalline polymorphic modifications. In all the cases considered, the dependency sections were linear at higher temperatures and completely coincided with the cooling curves in the given temperature range, thus reflecting the structural homogeneity of the liquid crystalline phase. At temperatures below 30 °C, hysteresis was observed, resulting in cooling curves passing below the heating curves and containing bends corresponding to the melting temperatures of their low-melting α -forms. Both dependencies of the repeated melting-cooling cycle coincided with the cooling dependency of the first. The use of rapid cooling technique for fats melted at 40, 70 and 90 °С allowed desaturation processes of fatty acids in their liquid crystalline phase to be recorded. Regardless of the component ratio, a study of beef and pork fat blends demonstrated a decrease in the melting point of the α -forms in all cases to 25 °C, i.e. noticeably lower than the melting point of the original fat. However, at lower temperatures, the cooling curves diverge, indicating a difference in the melting temperatures of their low-temperature modifications depending on the component composition of the system, as well as a corresponding difference in structural, optical and biochemical properties.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):63-76
63-76
Chemical technology
Lead (II) concentration by a chelating sorbent containing meta-phenylenediamine fragments
Аннотация
A sorbent based on a copolymer of maleic anhydride with styrene, containing m-phenylenediamine fragments was synthesised. After drying at 50–60 °С, the obtained sorbent was identified using IR spectroscopy. Further, a study of lead sorption by a synthesised sorbent was conducted. For this purpose, the effect of pH, time, ionic strength and metal concentration on sorption was determined. According to the experiment, the maximum sorption was established at рН = 6. Complete sorption of lead (II) wasobtained following 3 hours of metal contact with the sorbent. The effect of increase in ionic strength to 0.6 mol/L on sorption was shown to be insignificant, with a subsequent increase leading to a critical decrease in sorption value. The isotherm of lead sorption by the synthesised sorbent was constructed and the optimal concentration conditions studied. The analysis results demonstrated an increase in the concentration of lead (II) ions in the solution to provide higher values of sorbed metal concentration with the maximum occurring at a concentration of 6·10-3 mol/L (pH = 6, СPb+2= 6·10-3mol/L, Vsample= 20 mL, msorb.= 0.05 g, CE = 405 mg/g). Under optimal conditions, the extraction degree of lead (II) ions exceeds 95 %. The study of sorption was carried out both under static and dynamic conditions. Additionally, the effect of various mineral acids (HClO4, H2SO4, HNO3, HCl) of the equal concentration on the desorption of lead (II) from the sorbent was studied. The maximum desorption of lead (II) was obtained in sulphuric acid. Thus, the proposed express technique including preliminary concentration of lead (II) with a synthesised sorbent provides quantitative isolation of lead (II) from a large sample volume with a complex background composition.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):107-113
107-113
Selection of the most beneficial raw materials for the synthesis of biodiesel from a standpoint of its yield and physicochemical properties
Аннотация
Biodiesel presents itself as one of the most promising alternative energy sources at the present time, both as a pure fuel and a mixed component of petroleum-based diesel fuels. According to research works carried out around the world, the addition of biodiesel to diesel oil is established to significantly improve the environmental friendliness of this oil product. Nevertheless, its effect on most regulated operational indicators remains ambiguous due to the characteristics of biodiesel fuel varying greatly depending on the feed-stock. The present paper is aimed at resolving the issue of selecting the most beneficial raw material for the synthesis of biodiesel from the perspective of the target product yield, physicochemical and low temperature characteristics. In this study, biodiesel was synthesised from five different edible vegetable oils (sunflower, mustard, linseed, corn and camelina) using ethanol and potassium hydroxide as transesterifying agent and catalyst, respectively. The main physicochemical (density, dynamic and kinematic viscosity, molecular weight) and low-temperature (cloud point and pour point) properties of vegetable oils, as well as biodiesel fuels derived therefrom, are determined. According to the obtained yield values of the target product, sunflower oil is shown to be the optimal raw material for the synthesis of biodiesel. From the position of their physical and chemical properties, sunflower and corn oil appear to equally preferential, while, with regard to low temperature properties, mustard oil turns out to be the optimal feedstock. Sunflower oil was additionally determined to be a leader in terms of economics. The paper presents recommendations for choosing the most preferable raw materials for the synthesis of biodiesel, which are useful in application of biodiesel as a mixed component for commercial diesel fuels.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):114-123
114-123
Thermolysis waste processing in hydrolysis production
Аннотация
One of the urgent tasks of rational environmental management concerns the recycling of large-tonnages of industrial waste. Occupying significant landfill areas, accumulated waste acts as a source of environ-mental pollution, resulting in a decline in human living conditions. The great quantity of some carbon-containing wastes leads to their consideration as secondary technogenic raw material resources. In particular, since comprising an integral part of the structure of wood and accumulating in large quantities in the wastes of paper pulp and hydrolysis plants, lignin potentially forms a promising basis for producing a wide range of products, including aromatic aldehydes, alcohols, mineral fertilisers and feed additives. However, due to its high resistance to microbiological decomposition and propensity to spontaneous combustion (in dry form), the utilisation of lignin for such purposes presents certain difficulties. Additional limitations affecting existing technologies for lignin processing include the inability to efficiently process large volumes, as well as the remoteness of processing enterprises from storage sites. In the present article, the decomposition of lignin in a microwave thermolysis pilot plant comprising part of an existing waste recycling plant (Tombov, Russia) is investigated in connection with its disposal and extraction of target products. Under the applied microwave radiation, the decomposition time of lignin is reduced in comparison with the traditional method. This is combined with a decrease in volume of utilised substance complemented by its neutralisation and cleaning of pathogenic microorganisms. Based on the results of the study, the technological parameters of the process are determined and the average estimated yield of thermolysis products is provided. The resulting carbon residue can be ap-plied in the production of catalysts and carbon sorbents, while the liquid component can be used as a raw material for low-combustible fuel fractions. The existing gas cleaning system makes the process more environmentally friendly.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):124-132
124-132
Adsorption extraction of nickel (II) from industrial aqueous solutions
Аннотация
A scheme for the primary unit of a technological means for the adsorption extraction of nickel from industrial solutions resulting from the processing of oxidised nickel ores is presented. The solutions comprise an aqueous extract of complex compounds of transition metals from an ore having an initial nickel content of 1-2 %. The traditional stepwise treatment of the solutions is oriented towards sequential precipitation of metals by ammonia water in the form of hydroxides, involving their decantation and filtration, etc., which significantly complicates the process of obtaining the target metal. The adsorption process significantly increases the economic efficiency of the extraction process for this valuable metal. In terms of their properties, carbon sorbents are chemically resistant, able to endure the harsh conditions of high temperature exposure and treatments based on strongly acidic and strongly alkaline solutions. Moreover, such sorbents have a developed porous structure, a significant specific surface area and high mechanical strength. The process of nickel extraction using carbon adsorbents from solutions in a weakly alkaline environment at elevated temperatures is described. The scheme of the nickel (II) ion extraction by adsorption unit is based on the use of a fluidised bed whose operational parameters are calculated directly by studying the sorption of nickel ions. The adsorption extraction of nickel (II) ions facilitates the complete selective separation and derivation of the metal following desorption of a saturated solution making the process suitable for direct electrolytic metal production.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):133-139
133-139
Comparative studies of extraction methods of biologically-active substances with antioxidant properties from grape seed (Vitis vinifera L.)
Аннотация
The aim of the work was to compare the influence of extraction methods on the total phenol and flavonoid content as well as antiradical activity and reducing power of biologically-active extracts obtained from grape seeds. The examined methods for obtaining by-products of wine production consisted of maceration, ultrasonic exposure and microwave irradiation. Research methods included a spectrophotometric approach used for determining the total content of phenols and flavonoids, the free radical of 2,2-diphenyl-1-picrylhydrazyl to evaluate antiradical activity, a ferric reducing ability of plasma (FRAP) assay to assess reducing power and a linoleic acid model to test antioxidant activity. The results show that ultrasonic techniques allow higher phenol and flavonoid content to be extracted from grape seed feedstock, yielding extracts with high antiradical activity, reducing power and antioxidant values. A similar effect on a number of parameters of grape seed extract is achieved exerted by microwave irradiation, although these parameters' values are lower. Thus, ultrasonic treatment can be recommended as an intensification method for obtaining grape seed extracts having high antioxidant activity, frequently used as a component of many biologically active additives, as well as in various cosmetic products.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):140-148
140-148
Determination of equivalent alkane carbon number for West Siberian oils as a stage of optimisation in surfactant-polymer compositions for chemical flooding
Аннотация
The hydrophobicity of oil and oil products can be characterised in terms of its equivalent alkane carbon number (EACN). This characteristic can be determined on the basis of the correlation between the interfacial tension data and other characteristics for homologous oils and a number of alkanes having subsequent interpretation for oil and oil products. The EACN is a useful metric for selecting an effective surfactant for the emulsification of oil and oil products. The research is aimed at determining the equivalent alkane car-bon number of various crude oil samples obtained in the oil fields of Western Siberia using standard high-performance compositions of imported and domestic industrial sulphonate surfactants. In order to determine the EACN of oil and oil products, the S* characteristic was applied representing the optimal NaCl concentration (optimum salinity) in the aqueous surfactant phase, as well as providing the minimum surface tension and formation of the maximum microemulsion volume during the phase experiment at the interface with the hydro-carbon phase. Direct determination of the interfacial tension at the "oil / surfactant solution" interface was car-ried out with a tensiometer using the spinning drop method at a temperature of 87 °С. Linear dependencies are identified in accordance to the empirical correlation equations between the EACN, surfactant parameters and phase behaviour parameters of aqueous surfactant solutions and oil or a mixture of hydrocarbons. The K characteristic parameter of the proposed three standard surfactant compositions is determined to be consistent with the literature data for individual surfactants. The composition of industrial surfactants for determining the EACN of oil and oil products is proposed. The equations of linear regression for the logS* ~ EACN dependency with high correlation coefficients (R² = 0.9444-0.9999) are obtained, resulting in the determination of the EACN for kerosene and seven oil samples from Western Siberian oil fields. Promising surfactants can be selected on the basis of this indicator for reducing interfacial tension in the "hydrocarbon / water solution" system, as well as for predicting the most effective composition for obtaining emulsions.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):149-158
149-158
Barrier property features of various sands of the South-Western Baikal region in relation to typical environmentally hazardous wastewater
Аннотация
To determine the barrier properties of some sands of the southwestern coast of Lake Baikal, their holding capacity of such aggressive substances as petroleum products (tested on the example of gasoline emulsion) and household wastewater (tested on the example of surface-active substances (surfactants) and acommon household liquid detergent "Biolan") was evaluated. The throughput capacity of sands with respect to carriers imitating domestic wastewater was studied along with the adsorption capacity with respect to individual surfactants – in this case, typical detergents (sodium oleate, sodium dodecyl sulphate, sodium hexadecyl sulphate and sodium tetradecyl sulphate). It was established that holding capacity with respect to oil products and domestic wastewater varies according to the different source locations of sand samples obtained from the southwestern Baikal region. For instance, sands from the Baikal lake coast near the village Khuzhir possess the highest holding capacity for gasoline effluent; this capacity decreases for the sand samples collected near Baykalsk and Angasolka, and is most insignificant for sand samples derived from Obuteikha. Although this difference may be attributed to many factors, the most significant of these is particle size distribution. In relation to the effluents of the Biolan household detergent, the holding capacity of the sands predominantly depends on the crystalline chemical composition, with the best properties in this series of experiments being demonstrated by the sand obtained from Angasolka containing the clay mineral antophyllite. The results of adsorption tests showed that individual surfactants can be adsorbed on the surface of mineral particles via a molecular or micellar mechanism. It has been suggested that the adsorption mechanism depends both on the crystallographic features of mineral adsorbents and on the composition and structure of surfactant molecules. Thus, it is shown that, in terms of their inherent qualities, natural sands occurring in the southwestern coast of Lake Baikal can serve as a protective barrier for underlying soils and groundwater.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):159-168
159-168
Brief communication
Chemical modification of functional copolymers
Аннотация
The possibility of chemical modification of thermally-stable functional copolymers of 1-vinyl-1,2,4-triazole with vinyl acetate of various compositions synthesized under conditions of free-radical polymerisation in the presence of azobisisobutyronitrile was studied. Modification of the copolymers was carried out by alkaline hydrolysis; as a result, new copolymers containing vinyl triazole and vinyl alcohol units in the macromolecules were obtained. The structure, composition, physical and chemical properties of the copolymers were determined using elemental analysis, infrared spectroscopy and thermogravimetric analysis. With an increase in the number of vinyl alcohol units in the copolymer from 25 to 87 mol %, a nearly twofold reduction in the intrinsic viscosity of the copolymers was observed. The copolymers, which exhibit dielectric properties, are characterised by electrical conductivity of the order of Ш14-10-15 S/cm. According to thermogravimetric analysis data, the copolymers are resistant to thermooxidative degradation up to 270-290 °C depending on the composition. The introduction of a vinyl alcohol fragment into the structure of copolymer macromolecules contributed to the improvement of their fibre- and film-forming properties - that is, fibres and transparent elastic films with good adhesion to various metal surfaces can be formed from solutions of modified copolymers based on 1-vinyl-1,2,4-triazole.
Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya. 2020;10(1):169-173
169-173