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Vol. 5 Issue 2

Archives Journal Chemical Bulletin Vol. 5 Issue 2

SYNTHESIS OF GRAFT COPOLYMERS BASED ON SKF-32 BY ATOM TRANSFER RADICAL POLYMERIZATION

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 7-18 p.
Abstract
The use of partially fluorinated polymer electrolyte membranes in fuel cells is a very promising approach. Due to this, it is possible to avoid the disadvantages that arise when using perfluorinated polymers containing sulfonate groups as proton exchange membranes. Such disadvantages include high cost, unsatisfactory characteristics of proton transport with low water content and high values of hydrogen permeability through the membrane. Materials based on vinylidene fluoride are representative partially fluorinated polymers that exhibit interesting thermal, chemical, physical and technological properties. One of the promising directions for creating proton-exchange membranes is creation of graft fluoropolymers containing sulfonate groups. Samples of grafted copolymers based on industrial fluoroelastomer SKF-32 (a copolymer of vinylidene fluoride and chlorotrifluoro-ethylene) was carried out by grafting styrene with subsequent sulfonation. Graft poly(vinylidene fluoride-co-chlorotrifluoroethylene-g-styrene) was synthesized by atom transfer radical polymerization (ATRP). The data of viscometry and FT-IR spectroscopy allow us to conclude about the successful grafting of polystyrene fragments. Sulfonation of the grafted copolymer was carried out by injecting an acetyl sulfate solution to a polymer solution in 1,2-dichloroethane at a temperature of 40°C for 3 hours in an argon atmosphere. The qualitative composition, characteristic viscosity, molecular weight distribution and concentration of sulfogroups in the studied samples were investigated. The concentration of cross-linked polymer chains increases with an increase in the duration of synthesis, which complicates the sulfonation process. Optimal synthesis conditions were determined: temperature 90оC, initiator ‒ 2,2’-bipyridyl, duration – 3-4 h. Under these conditions, the highest yield of the finished product is achieved and unintentional crosslinking of the polymer does not occur.
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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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