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2022

Archives Journal Chemical Bulletin Vol. 5

ISOLATION OF CELLULOSE FROM TYPHA LATIFOLIA BY THE NITRIC ACID DELIGNIFICATION METHOD

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 19-29 p.
Abstract
The material of the article considers the production of cellulose from broadleaf cattail by the nitrate method as one of the ways to process spent cattail after a cycle of filtration of water bodies in order to provide a potential effective natural biofilter in an economical way of disposal. Morphological differences of plants in composition, structure, packing density, conformation of molecules do not allow equally effective application of the same methods of material processing, which requires adjustment of the process conditions. For the nitric acid method, the process conditions were optimized in terms of the time parameters of soaking in solutions of nitric acid and alkali for its application to broadleaf cattail with the highest yield of the target product. The isolated cellulose by the nitric acid method satisfies the basic requirements for the content of α-cellulose and residual lignin to obtain a wide range of further products, including the synthesis of cellulose nitrates for the defense industry with the possibility of selecting processing conditions to obtain the required composition. Also, broadleaf cattail proved to be a relatively capacious source of holocellulose. The paper presents the mass fraction of holocellulose in samples subjected to different processing time parameters, the content of α-cellulose and residual lignin in holocellulose from broadleaf cattail.
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ANALYSIS OF MAGNETITE IN THE FE3O4/C NANOCOMPOSITE

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 30-41 p.
Abstract
This paper presents the magnetite study results of a Fe3O4/C nanocomposite obtained with air pyrolysis of a heterogeneous system which includes iron dichloride tetrahydrate – the source of magnetite nanoparticles (NPs) – and polyacrylonitrile (PAN) – the source of a carbon shell for nanoparticles protection from issues like aggregation. Methods such as Mössbauer spectroscopy and X-ray diffraction analysis are used for studying and determine the magnetite NP formation way. There are two types of NPs in the system studied: ferrimagnetic and superparamagnetic ones, the difference between which is clearly watched when taking Mössbauer spectra – sextets and doublets relatively. All magnetite NPs are established to be formed according to the reaction chain the inter-mediate elements of which is ferrous carbonate well-known for its decomposition into magnetite upon heating: FeCl2 → FeCO3 → Fe3O4. This transformation occurs in the temperature range from 200 oC to 400 oC above which an ability of the carbon shell to protect NPs is gradually reduced that leads to agglomeration and oxidation to hematite α-Fe2O3.
To study the magnetite obtained, size distribution of magnetite crystallites and the degree of nonstoichiometry are estimated. According to various calculations, the average crystallite size is 9-10 nm.
To preserve the NP properties, storage methods are important to be chosen properly, thence Mössbauer spec-troscopy of the Fe3O4/C nanocomposite is carried out after keeping it in air at room temperature for 1 year.
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PRODUCTION OF PHENOL-FORMALDEHYDE SORBENTS FROM LEATHER INDUSTRY WASTE

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 42-52 p.
Abstract
The leather industry refers to material-intensive industries in which the cost of raw materials is about 70-80% of the cost of finished products, therefore, the rational use of raw materials through waste disposal is of particular importance. 40-50% of the area can be used, the rest is usually sent for burial or incineration. Both in the first and in the second case, this is not only economically inefficient, but also an environmentally hazardous way to get rid of these wastes. One of the ways to dispose of such waste (minnow and sawn trim) is to process them into hydrolysates and use them in the production of gelatin, adhesives and building materials. In this paper, the possibility of using collagen hydrolysates as a modifier of phenol-formaldehyde resins has been studied. The sorption of heavy metal ions by an oligomeric sorbent obtained by modifying phenol-formaldehyde resins with collagen hydrolysate was studied at various pH values, temperature, particle sizes, and metal ion concentrations. The physical and technical characteristics of the adsorbent are determined.
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CORRELATION OF HYDROCARBON AND NON-HYDROCARBON COMPONENTS OF DISPERSED GAS IN THE PERMAFROST ZONE OF WESTERN SIBERIA

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 53-66 p.
Abstract
The composition of dispersed gas in the permafrost zone of Western Siberia characterized by the heterogeneity of the distribution of hydrocarbon and non-hydrocarbon components both over the area and along the section. This work carried out to assess the influence of the lithological composition on the following indicators: methane and its homologues, olefins and hydrogen. The analysis is based on a chromatographic analysis of 199 samples taken from 6 wells. A latitudinal well profile selected to capture as much diversity in lithology as possible within the work area. Samples taken at a site located within a multi-layer gas condensate field in the Nadymsky district of the Yamalo-Nenets Autonomous Okrug in the zone of continuous permafrost (PFR). To minimize the influence of external factors on the data obtained, a shallow well core used for the study, which underwent degassing and further chromatographic analysis to determine hydrocarbon components from C1 to C8, as well as non-hydrocarbon gases: hydrogen, carbon dioxide and helium. The work based on the results on hydrogen, olefins, methane and its homologues up to C7. Correlation schemes built based on the lithological composition, and then on the content of individual components in the wells, an inter-well correlation made with the distribution of indicators. As a result, it turned out that almost always at the boundary of lithological differences, the gas content values decrease, and the drop in values at the boundaries of layers of different composition does not affect the distribution of components within individual layers, that is, they do not accumulate in a significant amount, this phenomenon does not fall under the concept "geochemical barrier" in connection with which the concept of "geochemical screen" is proposed.
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DEVELOPMENT OF ELECTRODE MATERIALS BASED ON PLATINUM- RUTHENIUM NANOPARTICLES FOR METHANOL FUEL CELLS

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 7-15 p.
Abstract
The creation of effective materials for the functioning of new chemical power sources is currently an urgent task. Fuel cells can use environmentally friendly and energy resources, such as hydrogen and carbon biofuels (methanol and ethanol), which have a wide range of potential applications from portable devices to power plants. The researcher’s attention is attracted by the development of methanol fuel cells, due to their compact design, liquid fuel, low operating temperature and high specific power. However, commercialization of such energy sources is still a difficult task due to the high platinum content on the electrodes, the high cost of precious metals, low durability and delayed kinetics of both anode and cathode reactions. Increasing the activity and reducing the Pt load are two main tasks in the development of methanol fuel cell technology. In the work, bimetallic Pt-Ru nanoparticles were synthesized by chemical reduction in reversed microemulsions to evaluate the parameters of methanol fuel cells. A porous nickel was used as a carrier matrix, which was formed by template synthesis in a dimensional mask of metallic aluminum. As a result of experimental studies of methanol membrane-electrode assemblies of fuel cells based on porous nickel with Pt and Pt-Ru nanoparticles, it was concluded that the maximum voltage and current density are achieved when using electrodes based on platinum-ruthenium nanoparticles with a particle size of no more than 3 nm, a catalyst content of 0.2 mg/cm2 and a process temperature of 60oC.
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PROMISING MONOMERS AND OLIGOMERS FOR OBTAINING AROMATIC POLYESTERS BASED ON THEM

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 16-26 p.
Abstract
New halogen-containing oligoesterketones have been synthesized by high-temperature polycondensation in an aprotic dipolar solvent in an inert gas atmosphere, and methods have been developed for producing new monomers and oligomers suitable for the production of aromatic polyesters based on halogen-containing monomers with the replacement of the traditional 4,4-difluorobenzophenone with a chlorine-containing monomer. The substantiation of the choice of the research task, the technical and economic aspects of the problem and the ways of its solution are presented. The task of synthesizing monomers and oligomers for the subsequent polymerization of aromatic polyesters is due to the importance of ensuring the relationship of the properties of the synthesized polymer from the list and characteristics of the base materials used. Thus, methods for obtaining monomers and oligomers based on them have been developed, correlation dependences of the properties of the obtained materials on the composition and quantity of fillers used have been investigated. Nucleophilic substitution reactions for the production of oligomers are described. The structures of the obtained monomers and oligomers are determined and possible areas of their application are established, data on the study of the properties of the obtained materials by IR spectroscopy, elemental and X-ray diffraction analysis, TGA, DSC, etc. are presented. The practical significance and applicability of the obtained materials and products for various purposes is proposed, taking into account the requirements for materials with high heat resistance, physico-mechanical, operational characteristics.
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RESEARCH OF THE COMPOSITION OF ORGANIC ACIDS IN THE THE FRUIT PRESS CAKE OF SEA BUCKTHORN CRUSHINOID

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 27-36 p.
Abstract
Sea buckthorn is a unique plant, the medicinal properties of which have been known since antiquity. The greatest value in medical practice is the product of processing the fruits of this plant - sea buckthorn oil. Today there is a problem of press cake utilization after receiving oil by cold pressing method. The organic acids contained in the sea buckthorn fruits are water-soluble, therefore, a minimum amount of them is extracted into the resulting oil, and the entire main part remains in the cake. Organic acids are indispensable elements necessary for the normal functioning of the human body, the study of their composition in the cake would later justify its use as a secondary raw material for various industries. Thus, the purpose of our study was to study the chemical composition of organic acids in sea buckthorn cake by high performance liquid chromatography. Based on the data obtained, it can be concluded that the content of organic acids in the cake is quite high. In this connection, the most rational solution would be the implementation of waste-free production of sea buckthorn oil, involving the use of the re-maining raw materials as secondary raw materials for various industries.
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PREPARATION OF GLYCOLIC ACID USING ELECTRODIALYSIS

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 37-53 p.
Abstract
Every day, more and more talk about the problem of ecology. Oddly enough, this problem will not lose its relevance for a long time. Modern life is impossible without chemistry: its processes and products are used by all industries: both extractive, and manufacturing, and agriculture, and the service sector. The depletion of natural resources and the problem of waste led science to the conclusion: humanity needs to radically change industrial technologies in order to preserve the planet. Chemistry has to become green – as wasteless and environmentally friendly as possible. Since every year there are more and more enterprises that harm nature. Accordingly, it is necessary to deal radically with this problem, which as a result can open up new ways for the development of all industry. In most cases, each industry has ways to reduce harmful emissions and harm to the environment. To this end, more and more "cleaner" ways of obtaining products are being developed. The purpose of the article is to develop a method for producing glycolic acid by electrodialysis. This method enables to obtain glycolic acid in industrial quantities with high product yield and minimal environmental damage. As a result of the study, the technological scheme of the plant for converting sodium glycolate to glycolic acid was developed, equipment was selected, on the basis of technical and economic analysis, the following were estimated: cost of product, profitability of production and payback period.
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KINETICS OF DISSOLUTION OF CR(OH)3 AND AL(OH)3 IN SULFURIC ACID

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 54-60 p.
Abstract
This work is a continuation of studies related to the kinetics of dissolution of oxides and hydroxides of aluminum (III) and chromium (III). Earlier studies have shown that oxides and hydroxides of these metals are better soluble in sulfuric acid than in hydrochloric, nitric, oxalic and phosphoric. This article presents experimental studies on the effect of sulfuric acid concentration on the rate of heterogeneous reaction of chromium (III) and aluminum (III) hydroxides. It is established that the rate of dissolution of hydroxides increases with increasing concentration of sulfuric acid. Moreover, the rate of transition of aluminum (III) ions from hydroxide is higher than the rate of transition of chromium (III) ions, under the same conditions. To calculate the main kinetic parameters, a model of a chain mechanism was selected. The dissolution simulation was carried out using the mathematical computer program MathCad. The need for real models is associated with the need to optimize ore leaching technologies, regulate the physico-chemical processes of oxide dissolution, scale etching and removal of deposits from thermal power equipment. Experimental studies have made it possible to determine that the rate of dissolution is limited by the formation and subsequent transition of surface compounds of the form: into an electrolyte solution. Such studies will help to create a generalized mechanism for the heterogeneous process of dissolution of aluminum and chromium oxides in acidic media.
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SYNTHESIS OF POLYMERIC MATERIALS BASED ON AROMATIC POLYESTER MATERIALS BY HIGH-TEMPERATURE POLYCONDENSATION

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 61-73 p.
Abstract
As part of solving the problem of creating recipes for the synthesis of domestic superconstruction polymers, work was carried out on the synthesis of aromatic polyester materials with a complex of valuable performance characteristics. It has been established that it is possible to improve the economic performance of the PCM synthesis process based on aromatic polyesters by replacing the traditional 4,4'-difluorobenzophenone monomer with a chlorine-containing functional analog, which makes it possible to synthesize new materials with a cost up to 6 times lower than known competitors. The paper studies the features and determines the optimal conditions for the synthesis of new aromatic polyester materials: oligoetherketones and polyetherketones, polyimides and polyeth-erimides, to create binders for the impregnation of glass and carbon reinforcing fillers. It is described that the syn-thesis of polyimides (PI) was carried out by a two-stage method: obtaining a polyamic acid (PAA) and obtaining an insoluble diversified polymer. It has been established that by replacing the expensive dihalide, it is possible to a large extent to reduce the cost of synthesized polymers, increase their yield and manufacturability. A complex of physicochemical studies by various methods has been carried out, the structure of the synthesized polymers has been established, it has been determined that new polyester materials based on poly(aryleneetherketones) and pol-yetherimides are superior in their basic physicochemical and operational properties to industrial analogous poly-ester superstructural materials.
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