Fine Chemical Technologies (E-Journal) / Тонкие химические технологии
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СОСТАВ И СТРОЕНИЕ СОЕДИНЕНИЙ СЕМЕЙСТВА ХАНТИТА
Get PDFThe literature data on the composition and structure of rare-earth borate compounds of the huntite family with the general composition LnM3(BO3)4, where Ln3+ = Y, La = Lu and M3+ = Al, Fe, Cr, Ga, Sc as well as a number of solid solutions with М3+ = Sc are systematized. The difference between the real compositions of crystals and the compositions of the initial mixture, the most characteristic of rare-earth scandium borates, is shown. The significant role of the composition in the manifestation of the compounds symmetry is established. The necessity of determining the crystals symmetry only on single-crystals with detailed analysis of diffraction reflections is proved. Morphotropic series were selected depending on changes in the ionic radii of Ln and M. Attention is paid to the peculiarity of the structural behavior of Cr3+ ions. It was revealed that the formation of solid solutions and internal solid solutions is most likely for rare-earth scandium borates. The implementation of polytypic modifications for LnM3(BO3)4, where M3+ = Al, Cr, and polymorphs for a number of Ln ions with M3+ = Fe, the existence of which is not excluded for M3+ = Sc, is demonstrated. Crystal-chemical effects observed for huntite-like crystals (morphotropy, isomorphism, polymorphism, polytypy; internal solid solutions; phase order-disorder phase transitions of different nature) with specific features of scandium borates are presented. The realization of polymorphism and polytypism for compounds of the huntite family confirms the crystal-chemical situation, according to which hightemperature polymorphic modifications should form more symmetrical compounds, but it is not typical of polytypic modifications
КАВИТАЦИОННАЯ ОБРАБОТКА ДИЗЕЛЬНОЙ ФРАКЦИИ НЕФТИ
Get PDFThe results of investigation on the effect of mechanochemical treatment of the diesel fraction on its physicochemical characteristics are presented. Mechanochemical treatment of the diesel fraction was achieved by creating a cavitation effect in the hydrodynamic regime. The studies were carried out in the range of pressure gradients up to 50 MPa, the number of treatment cycles varied from 1 to 5, the temperature of raw material at the apparatus inlet was 0 0С. It is shown that the effect of cavitation is manifested not only in the processing of high-boiling hydrocarbons, but also in a middle distillate directions. So, as a result of the cavitation effect, the density of the diesel fraction and its pour point decrease, and the fractional composition changes. It is suggested that these changes are associated with hydrocarbon degradation. The collapse of gas bubbles leads to a local increase in the temperature of the medium to 800 0C, which, in turn, leads to the destruction of hydrocarbons. Increasing the pressure gradient of the hydrodynamic flow enhances the noted effect. Increasing the number of treatment cycles reduces the effect achieved. A possible reason is the destruction of hydrocarbons formed in the first stage of processing and the formation of polycyclic and aromatic structures. The results presented in the article extend ideas about cavitation regularities in the hydrocarbon environmen
ИССЛЕДОВАНИЕ СВОЙСТВ ВУЛКАНИЗАТОВ НА ОСНОВЕ ЭТИЛЕНВИНИЛАЦЕТАТНЫХ КАУЧУКОВ С РАЗЛИЧНЫМ СОДЕРЖАНИЕМ ЗВЕНЬЕВ ВИНИЛАЦЕТАТА
Get PDFThe article studies the structure and properties of ethylene vinyl acetate rubbers and the influence of the vinyl acetate (VA) units content in the rubber on the technological, physical-mechanical, operating and electrical properties of vulcanizates. The results of the study prove that the distinctive feature of ethylene vinyl acetate rubbers compared to other rubbers is their thermoplastic properties and low viscosity. Besides, the high resistance to ozone, heat and oil resistance and good mechanical properties of vulcanizates based on them make this type of polymer materials very promising for the creation of modern products. It is shown that the values of elasticity modulus, strength, elongation and tear resistance are increased with increasing VA units content in the rubber. Besides, swelling in hydrocarbon media decreases. Vulcanizates containing 40-45% of VA have satisfactory electrical characteristics and good moisture resistance and can be used as the base insulating rubber. Vulcanizates with a high content of vinyl acetate units (60-70%) have high oil and heat resistance. Therefore, their use in rubber compounds for cable jackets is most effective. The study of the properties of ethylene vinyl acetate rubbers and their vulcanizates allowed to develop formulations of insulating and jacket rubbers and to determine the most promising areas of their application for modern cable products of special purpose in the petrochemical, aerospace, transport and shipbuilding industries
СПОСОБЫ БОРЬБЫ С БИОПЛЕНКАМИ НА ПОВЕРХНОСТИ ПОЛИМЕРНЫХ МАТЕРИАЛОВ
Get PDFOne of the harmful factors of the interaction of microorganisms with the technosphere is the formation of biofilms on the surface of various products. Steady colonies of bacteria ensure a stable contamination of the handling medium of the product, and their release is a cause of biodestructive processes in materials. In many cases, single or even regular antimicrobial treatment does not lead to complete suppression of colony formation. Therefore, today the most demanded methods of preventing biofilms formation involve the creation of materials that are resistant to colonization by bacteria. Since bacteria cells directly interact with the surface of the material, it is the surface that should have antibacterial properties. In the review, various methods of preventing the formation of biofilms by the example of polymeric materials are considered. The main attention is paid to the methods of creating antibacterial surfaces, which in various ways prevent the formation of biofilms. In accordance with the world practice, all antibacterial surfaces are divided into four types: releasing, contact-active, repelling and self-polishing. The advantages and disadvantages of each type of antibacterial surfaces, their existing limitations in use and prospects for further development are noted. Information on the compatibility of individual types of surfaces is also noted in the literature
АМПЕРОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ ПЕРРЕНАТ-АНИОНА НА МИКРОГРАНИЦЕ МЕЖДУ ДВУМЯ НЕСМЕШИВАЮЩИМИСЯ РАСТВОРАМИ ЭЛЕКТРОЛИТОВ
Get PDFVoltammetric responses associated with the simple reaction of perrhenate anions transfer across polarized micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) was investigated, and their sensing applications were demonstrated. The micro-ITIES array was formed at polyethylene terephthalate membranes containing a 196 microhole array of radius 10.0±0.1 μm using a femtosecond laser. The characteristics of perrhenate ions transfer at the water/2-nitrophenyloctyl ether interface were first investigated using cyclic voltammetry (CV). CV was used in the estimation of some of the perrhenate anions thermodynamic parameters, such as the formal transfer potential and the Gibbs transfer energy. The technique of alternating current stripping voltammetry (ACSV) was also utilized to improve the sensitivity of the perrhenate anion detection. Under optimized preconcentration and detection conditions, a limit of detection of 0.3 μM with a wide linear dynamic range extending from 1.0 to 100 μM was achieved. The effect of various potential interfering anions on the perrhenate sensor was also investigated and an excellent selectivity over SCN-, I-, NO3-, NO2-, CO32-, SO42-, MoO42-, WO42- and CH3COO- ions was also achieved. This enabled quantitative measurements of rhenium in some mineral raw samples and the data was also validated by comparing with inductively coupled plasma atomic emission spectroscopy
СИНТЕЗ СХЕМ РАЗДЕЛЕНИЯ РАССЛАИВАЮЩИХСЯ СМЕСЕЙ: СОВРЕМЕННОЕ СОСТОЯНИЕ ПРОБЛЕМЫ
Get PDFThe paper presents an analysis of the current state of research on separation flowsheets based on the combination of distillation and phase separation processes, as well as heteroazeotropic distillation. It is shown that the works of foreign researchers devoted to the study of flowhseets with decanters are more focused on finding ways to reduce energy consumption by introducing additional separators, a combination of several methods (extractive and heteroazeotropic complex columns with external decanters. The task of synthesizing all possible separation flowsheets is not considered in these works. In this paper, a complete set of flowsheets of different structures based on the combination of distillation and phase separation processes, including the use of columns with an external decanter, is proposed for water - butyl acetate - methanol and methanol - heptane-water ternary mixtures separation. Aspen Plus and NRTL model were used for mathematical modelling of phase equilibrium (the relative error of describing liquid-vapor and liquid-liquid equilibrium is less than 5%) was chosen as a method of research. Operating parameters for distillation columns (the number of theoretical plates, feed plate, reflux ratio) and the total energy consumption were obtained for each case. The necessity of using a double feed-plate column for separating of propanol-1 - water - butanol-1 and ethyl acetate - water - butyl acetate ternary systems was explained by the presence of extractive effect. Analytical review of modern publications and results of own research allowed to formulate a number of recommendations for the synthesis of energy effective flowsheets based on a combination of distillation and phase separation processes
КОНКУРЕНЦИЯ КИСЛОРОД- И АЗОТСОДЕРЖАЩИХ ДОНОРНЫХ ЛИГАНДОВ ПРИ КОМПЛЕКСООБРАЗОВАНИИ МЕДИ С 2-(ФЕНИЛ-4-ХЛОРФЕНИЛАЦЕТИЛ)ИНДАНДИОНОМ-1,3
Get PDFThe interaction of CuCl and 2-(phenyl-4-chlorophenylacetyl)indandione-1,3 (HL, C23H15ClO3) in a mixed organic solvent (CH3CN, C5H5N, EtOH) gave a solvated crystal complex of copper(II) of composition [Cu(C2H5OH)(L)2]•C2H5OH (I). The isolated compound was investigated by X-ray and IR spectroscopy methods. Lattice parameters of (I): space gr. P21/c, a = 14.982(1), b = 14.558(1), с = 20.608(2) Å; β= 105.176(2)°; Z = 4 (Z′=1). It is established that the structural units in the crystal structure of the obtained compounds are the neutral square-planar coordination spheres of Cu(II) with cis-oriented deprotonated indandionate ligands L. The spheres are located in the space pairwise. One molecule of EtOH is included in the internal sphere of the complex, and the second is a bridge that unites the coordination centers due to the hydrogen bonds between the hydrogen atom of the hydroxo group of the coordinated alcohol and the O-atom of the keto group of the adjacent bis-chelate. This results in a dimer structure. At the same time, in addition to ethanol, molecules of other co-solvents (CH3CN, C5H5N) do not participate in complex formation and do not form solvates. It was found that a copper(II) complex is formed from copper(I) chloride. When using copper(I) iodide as a starting compound in ethanol in the presence of pyridine the formation of the chelate with the deprotonated ligand HL is not observed
ГИДРОФОБНЫЕ ПОКРЫТИЯ НА ЦЕЛЛЮЛОЗНЫХ МАТЕРИАЛАХ
Get PDFA new hydrophobizator - tetra(ethoxy)di(octyl)disiloxane (TEDODS) - was synthesized in an ethanol solution at boiling point for 6 hours and characterized by NMR and IR spectroscopy. New hydrophobic coatings based on this compound were obtained under mild conditions by direct chemical modification of the surfaces of the cellulose materials (textile of different composition). The formation of a modified layer on the materials surface occurs due to the interaction of the ethoxy groups of the modifier and the hydroxyl groups of cellulose followed by heat treatment to fix it on the materials surface. The optimal conditions for obtaining the coatings were determined: 8% TEDODS weight gain with maximum hydrophobicity, with a wetting angle of 135°. The properties of the modified cellulose materials were studied (hydrophobicity, moisture absorption, etc.). The efficiency of using tetraethoxydioctyldisiloxane as a hydrophobizator when the content from 1% and a relatively small thickness of the coating of 2 microns was shown. It was found that hydrophobic coatings on the surface of cellulosic materials have little effect on moisture absorption and breathability of the original tissue
ВЛИЯНИЕ НЕПОЛИМЕРНЫХ КОМПОНЕНТОВ РЕЗИНОВОЙ СМЕСИ НА ПОВЕРХНОСТНЫЕ СВОЙСТВА ЭЛАСТОМЕРНЫХ КОМПОЗИЦИЙ
Get PDFThe effect of non-polymeric components of a rubber mixture on the surface properties of butadienestyrene rubber obtained by solution polymerization was studied in the article. As non-polymeric components, ingredients widely used in the practice of the rubber industry were introduced into the rubber: fillers, surfactants of various types, and also sulfur - as a vulcanization agent. The surface free energy of the samples, a quantitative characteristic of the surface properties, was determined using the Owens-Wendt-Rabel-Kaelble method. It has been found that the surface properties of elastomeric compositions depend significantly on the solubility of the ingredients of the rubber composition and their adsorption properties. It has been shown that the most significant influence on the surface energy of butadiene-styrene rubber is exerted by the filler, on the surface of which rubber adsorption does not occur. The effect of surfactants on the surface energy of rubber compounds is different and depends on the nature of the surfactant. A partially soluble component - sulfur - in small quantities does not affect the surface energy of rubber samples. However, if it is present in the system in quantities greater than the solubility limit, it significantly reduces the surface free energy of the samples
ИНТЕГРАЛЬНОЕ ПРЕОБРАЗОВАНИЕ В ЧАСТИЧНО ОГРАНИЧЕННОЙ ОБЛАСТИ С РАДИАЛЬНЫМ ПОТОКОМ ТЕПЛОТЫ
Get PDFA mathematical theory is developed for constructing integral transformations in a partially bounded region with a radial heat flow - a massive body bounded from the inside by a cylindrical cavity. Constructed: an integral transformation, the image of the operator on the right side of the equation of unsteady heat conduction, the inversion formula for the image of the desired function. The proposed approach favorably differs from the classical theory of differential equations of mathematical physics for the construction of generalized integral transformations based on the eigenfunctions of the corresponding singular Sturm-Liouville problems. The developed method is based on the operational solution of the initial boundary problems of unsteady heat conduction with an initial function of a general form L2(r0,∞) belonging to the r > r0 region and homogeneous boundary conditions and is associated with the calculation of the Riemann-Mellin contour integrals from images containing various combinations of modified Bessel functions. At the same time, for the above-mentioned region, the method of Green's functions was developed by constructing integral representations of analytical solutions of the first, second and third boundary value problems through inhomogeneities in the initial formulation of the problem (boundary conditions, source function in the initial equation). Mathematical models for finding the corresponding Green's functions are formulated, and functional relations of all three Green functions included in the presented integral formula are written out with the help of the developed theory of integral transformations. The functional relations constructed in the article can be used when considering numerous special cases of practical thermal physics. The specific possible applications of the presented results in many areas of science and technology are given