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Vol 11, No 4 (2016)
View or download the full issue PDF (Russian)
https://doi.org/10.32362/2410-6593-2016-11-4

THEORETICAL BASES OF CHEMICAL TECHNOLOGY

5-14 155
Abstract
In this work the structures of phase equilibrium diagrams of multiphase four-component systems n-hexane (n-heptane, n-octane) - cyclohexane - furfural - water were investigated. The systems are characterized by the existence of areas of three-phase separation. On the basis of the obtained data the synthesis of feasible variants of separation schemes was carried out, rational modes of functioning of each column were found, the energetically favorable variant was chosen. It was found that the use of preliminary phase separation in systems with n-hexane and n-octane is power-efficient, and the profit in case of the octane system (equimolar mixture) in comparison with the application of the first predetermined separation at the first stage is more than 25%. Certain difficulties (the high values of columns effectiveness: 60 and 40 theoretical plates) upon the separation of the hexane and heptane systems are due to the similar volatilities of n-hexane (n-heptane) and cyclohexane in the vicinity of the point of pure alkane.
15-25 121
Abstract
In this article, the normal continuous mode of distillation is considered using an example of binary two-phase mixture distillation. In practice, there are often deviations from the normal mode. It has been proved that the deviation leads to an increase in energy consumption for the ongoing process. In the industry, columns separating binary mixtures are normally the finishing apparatuses in the flow-sheet separation of multicomponent mixtures, which are obtained in the reactor as a result of main reactions as well as by-reactions. The distillation of binary mixtures is relatively simpler than that of multicomponent mixtures. In this regard, the fundamental parts of monographs especially in the thirties-forties of the last century started with the study of binary mixtures, although multicomponent mixtures were the main focus. The aim of analyzing this complex and the highly energy-intensive process is to facilitate the choice of a mathematical model for the process and the determination on its basis variance. Variance is a set of independent variables that allow calculation of a process only after taking into account the number of independent equations related to these variables. A case of deviation from the normal distillation regime where an under-heated liquid enters the column feed has been revised. This leads to an increase in energy consumption during distillation. Key indicators of the normal regime relative to the level of feed and the temperature of the liquid are shown in the text.

CHEMISTRY AND TECHNOLOGY OF ORGANIC SUBSTANCES

26-34 180
Abstract
It was studied the epoxidation mechanism of allyl alcohol using titanosilicate zeolite (TS-1) at 40°C by means of procedures for the nomination and discrimination of mechanism hypotheses. The hypotheses was carried out using the literature data and the preliminary experiment results. Discrimination hypothetical mechanisms implemented on the basis of the univariate results of the kinetic experiment, varying concentrations of allyl alcohol, hydrogen peroxide and glycidol. The most probable mechanism involves the hydrogen peroxide and allyl alcohol adsorption at the catalyst active centers and the glycidol formation at a reversible stage in the interaction of the adsorbed molecules of the reactants. Considered hypotheses include a different sequence of interaction of the reactants with active catalyst centre. In addition, hypotheses take into account the formation of intermediate compounds as well as inactive products of the interaction of substances present in the reaction system, with the active centers on the silicalite surface. For each hypothesis, it was formulated the corresponding system of differential equations and carried out the estimation of the rate constants. The quality of the experimental data description was judged by the residual sums of squared deviations and correlation coefficients. The best results are obtained for the hypothesis involving the hydrogen peroxide and allyl alcohol adsorption at the two active catalyst centers with subsequent interaction of the resultant intermediates between them, with the formation of glycidol adsorbed on one center, free catalyst centre and molecule of water. Formation of free glycidol occurs at a reversible stage. A significant part of the active centers of the catalyst increasing the concentration of glycidol is associated with it. This is the main reason for the decrease of the reaction rate, apart from reducing the concentration of the reactants.
35-42 105
Abstract
The process of natural gas drying leads to accumulation of unstudied organic impurities in the used absorbent solutions. These impurities reduce the drying capacity of triethylene glycol. In order to increase the effectiveness of installations for drying natural gas it is necessary to purify triethylene glycol from the accumulated impurities. The absence of information on the structure and properties of these impurities considerably complicates the purification of the absorbent solutions. In this study the structures of impurities accumulated in triethylene glycol were determined by NMR and high resolution mass-spectrometry coupled with chromatography (HPLC-MS/MS). The obtained results will enable to improve the existing methods for the purification of the working solutions of the absorbent.

CHEMISTRY AND TECHNOLOGY OF INORGANIC MATERIALS

43-49 143
Abstract
The aim of the this work is the synthesis and study (IR, single crystal XRD, DTG) of complex compounds of chlorides and bromides of lanthanum, neodymium, holmium, and erbium with acetamide [Ln(AA)4(H2O)4]Cl3·H2O (Ln = La, Nd, Ho, Er ) and [La(AA)4(H2O)4]Br3·H2O. Ligands (Ln) coordination occurs through the oxygen atoms, and the coordination polyhedra of the Ln atoms are distorted tetragonal antiprisms or two-capped trigonal prisms (CN = 8). All the studied complexes are characterized by a developed system of hydrogen bonds with the bromide or chloride ions (and outer-sphere water molecules) in the cavities of the structure formed by the complex cations. The features of the complexes thermal decomposition are discussed.
50-55 126
Abstract
This work is devoted to comparison of optical absorption value of titanium dioxide coatings obtained by means of reactive thermal evaporation (RTE) and its activated species (ARTE), as well as to study on the dependence of the absorption coefficient of the coatings on the process parameters. Special attention is paid to the study of the influence of the films nonstoichiometry on absorption in the visible and near-infrared ranges of the spectrum. The results allow concluding that the dominant mechanism responsible for absorption in titanium dioxide films in the near-infrared range of the spectrum is the deviation from the stoichiometric composition. This deviation is caused by the presence of defects in the coating structure such as oxygen vacancies (ions Ti3+), which are seen as electron traps. As oxygen pressure and ionic current increase, the absorption of titanium dioxide films is reduced, and films with a composition closer to stoichiometric are obtained. In turn, the absorption of titanium dioxide in the visible spectrum (at wavelengths of 532 nm and 670 nm) has less to do with defects in stoichiometry, in contrast to contaminating impurities contained in the starting material, in the vacuum chamber and in the jet gas.

SYNTHESIS AND PROCESSING OF POLYMERS AND POLYMERIC COMPOSITES

56-62 179
Abstract
The synthesis of polymeric suspensions with a narrow particle size distribution is an urgent problem in modern science. The resulting polymeric microspheres are applicable in various fields of chemistry, pharmaceuticals, biology and medicine. In particular, they can be used as carriers of bioligands to create diagnostic test systems. This article presents the results of a study on the colloid-chemical characteristics of water-insoluble fluorinated silicone surfactants and kinetics of the polymerization process in their presence. The results were compared with data from studies on the properties of surfactants of similar structure not containing fluorine atoms in their structure. Studying these substances’ rheology enabled to determine the most suitable surfactants for adsorption forming a strong interfacial layer during the formation of polymermonomer particles during the polymerisation. The ability of fluorinated silicone surfactants to form a stable polymeric slurry was proved during heterophase polymerization of vinyl monomers. The resulting polymeric suspensions were characterized by a narrow particle size distribution and high aggregative stability during the synthesis and in storage.
63-68 108
Abstract
The influence of silica dioxide nanoparticles in the form of fumed silica BS-50 on the rheological properties, residual shrinkage and shrinkage stresses upon curing an epoxy resin is considered. It is shown that the introduction of BS-50 in the optimum concentration of nanoparticles into DER-330 epoxy resin results in agglomeration, which is accompanied by an abnormal behavior of the disperse system with a decrease in viscosity by ~ 25%, ultimate shrinkage by ~ 15% and the level of residual stresses by a factor of ~ 4-10. These properties are manifested when the concentration of fumed silica is 0.05 vol. % The introduction of fumed silica slows the rise of residual stresses and increases the induction period from 2 to 4 hours. Depending on the mode of curing the minimum residual stress is observed at different concentrations of BS-50. At temperatures of 30ºC and 50°C concentration was 0.5 vol. %, and at 70°C - 0.05 vol. %. Curing at 30°C and 50°C result in a fall of residual stress by a factor of 12 and 4, respectively, at 70°C, by a factor of 4.

MATHEMATICAL METHODS AND INFORMATION SYSTEMS IN CHEMICAL TECHNOLOGY

69-74 118
Abstract
A prognostic model for constructing hypotheses about the relationship of combinations of cytokines with the proliferative activity of cancer cells is proposed. The model is based on the use of inductive inference methods. The methodology takes into account the synergistic interaction of cytokines and uses sequential construction of logical formulas for selecting groups of cytokines, a statistical analysis of contingency tables and logical integration of the obtained estimates. Implementation of the proposed method in the information system of forecasting the effect of targeted anticancer drugs in immunotherapy will greatly accelerate research in this area.


ISSN 2410-6593 (Print)
ISSN 2686-7575 (Online)