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Vol. 5 Issue 1

Archives Journal Chemical Bulletin Vol. 5 Issue 1

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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FORMATION AND RESEARCH OF BIMETALLIC ELECTRODE MATERIALS ON POLYMER-CARBON CARRIER MATRICES FOR ENERGY POWER SOURCES

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 74-82 p.
Abstract
Fuel cells are promising devices for direct conversion of chemical energy into electrical energy from the point of view of efficiency and low emission of pollutants. The main component of fuel cells is a solid polymer electrolyte. Membranes made of perfluorinated sulfonated copolymers of the Nafion type with different content of sulfogroups satisfy most of the application conditions, because they have a sufficiently high degree of proton conductivity, stability in electrolyte solutions and high mechanical strength. The principal disadvantage of such membranes is their relatively low ion selectivity and a decrease in mechanical strength at temperatures above 100oC. To improve the characteristics of the membrane, various modification methods are used, including various additives and metal nanoparticles. The main obstacle to the widespread large-scale use of fuel cells is their cost, in which the main part is the cost of electrocatalysts based on platinum metals. Therefore, the development of effective electrode materials with a reduced content of platinum metals is an urgent task. In this work, bimetallic platinum-ruthenium nanoparticles were synthesized on combined carrier matrices consisting of a Nafion polymer membrane and carbon nanotubes. The sizes of Pt-Ru nanoparticles were compared with varying the molar ratio of wa-ter:surfactant from 1.5 to 8. It was found that the minimum size is characteristic of nanoparticles obtained with a maximum platinum content in nanoparticles (7:1) and the degree of solubilization ω = 1.5. It was found that in the methanol oxidation reaction, electrode materials based on bimetallic Pt-Ru nanoparticles (7:1) demonstrate the greatest catalytic activity when the catalyst is loaded 0.2 mg/cm2 on polymer substrates with the addition of multi-walled carbon nanotubes at a temperature of 60oC.
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THE JOINT INFLUENCE OF SUCCAROSE AND HIGHLY DISPERSED CALCIUM HYDROSILICATES ON THE STRENGTH DEVELOPMENT KINETICS OF CEMENT CONCRETE

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 83-94 p.
Abstract
Сement hydration accelerator (highly dispersed calcium hydrosilicates) and hydration retarder (sucrose) are components of calcium silicate dispersion (CSD). Their joint influence on the processes of setting and hardening of cement composites is considered. The content of 10% CSD in the composition of the composite binder (CB) leads to a shift of the thermal maximum on the thermokinetic curve by a day. At the same time, at the late stages of hydration (>70 hours), the heat release rate remains consistently high, it is 2-3 times higher than the heat release rate of the control sample. The setting kinetics of CB pastes depends on the content of CSD in its composition and is of an extreme nature. The effectiveness of CSD in the composition of CB was evaluated on the example of ordinary heavy concrete (B25) with the replacement of cement with CSD. The results of assessing the change in the strength of concrete at CB are supplemented with calculated strength indicators in the future up to 1800 days hardening. The expected compressive strength of concrete samples on a composite binder is 1.8 times higher than the strength of the control sample.
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STUDY OF THE EFFECT OF ANIONS ON THE DISSOLUTION RATE OF CO2O3 AND CR(OH)3

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 95-100 p.
Abstract
Сhromium compounds are widely used in industry, therefore, studies related to the study of the process of dissolution of oxides in various environments, including aggressive ones, are relevant. Currently, a huge amount of experimental material has been accumulated on the dissolution of metal oxides and hydroxides. Despite this, the effect of anions on the dissolution rate of these compounds has not yet been sufficiently studied, models have not been developed and generalized dissolution mechanisms have not been found. This article presents experimental studies on the effect of nitrate and sulfate ions on the dissolution rate of chromium (III) oxide and hydroxide. It was found that chromium (III) oxide and hydroxide dissolve better in sulfuric acid in the presence of nitrate ions than sulfate ions. Moreover, chromium (III) hydroxide dissolves better in acids with the addition of anions than chromium (III) oxide. Based on the data obtained, using the equation of the chain mechanism (the Barton-Stransky model), we found the functional dependence of the specific rate of dissolution on the concentration of anions in an acidic medium. With the help of the mathematical computer program MathCad, models of the dissolution of chromium oxide phases were selected. A scheme of the mechanism of the heterogeneous process of dissolution of chromium oxide and hydroxide in acidic media was proposed.
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