Voprosy khimii i khimicheskoi tekhnologii (Issues of Chemistry and Chemical Technology)

20-25

Authors: V.N. Anisimov, V.V. Anisimov

It is shown that assessment of the properties of linear block-polyurethanes (BPUs) depending on the hardness, which is usually assumed as a basis of their sorting, disregards the features of the molecular structure and the nature of the initial components. A scientifically substantiated approach to the creation of BPU-based materials with an optimal molecular topology for tribological purposes was developed in this study. The effects of molecular weight of linear block-polyurethanes and oligomeric glycols of the methylene series on the deformation, thermophysical and tribological properties were investigated. Thus, the BPUs with the molecular weight of oligoglycols in the range of 500 to 2000 exhibit an efficient combination of high deformation characteristics and sufficient frame hardness. An increase in the degree of crystallinity from 1% to 20% results in ordering the structure of the BPUs and, consequently, a growth of elastic modulus from 15 MPa to 225 MPa. The use of esters of regular structure contributes to the minimum values of residual elongation and high wear resistance. In addition, the wearing intensity of BPUs with a molecular weight of oligoglycol of about 500 and of regular structures is seven times less than of polyurethanes based on oligoglycol with molecular weight of about 2000. It was also established that BPUs with molecular weights, that correspond to the characteristic viscosity []=0.8–1.0 dL/g, have the most optimal structural order, minimum values of wear intensity, and a high heat resistance. The change in the coefficient of friction as a function of the molecular weight is less pronounced, but it reproduces in detail the dependence of the wear intensity on the molecular weight. The conducted research and established dependences can be used to develop the branded range of BPUs.

34-45

Authors: P.V. Borovyk, S.I. Orysyk, H.H. Repich, A.F. Likhanov, A.M. Mishchenko, Yu.L. Zborovskii, V.V. Orysyk, L.G. Palchikovska, V.I. Pekhnyo, M.V. Vovk

The spectral characteristics of the synthesized cisplatin analogs based on -complexes of Pd(II) and Pt(II) with N-allylmorpholine-4-carbothioamide and 1-allyl-3-tret-butylthiourea and the mechanism of their cytostatic and antiproliferative action on meristem cells of Allium cepa L. are reported in this work for the first time. It is shown that the electronic absorption and diffuse reflection spectra of complexes show absorption bands corresponding to the transitions with charge transfer from a ligand to metal, dd-electron transitions and intraligand * and n* electronic transitions with the contributions of multiple bonds of allyl moiety and carbothioamide group. In this case, the absorption bands in the ultraviolet region of the spectra of the complexes undergo a hypochromic shift with respect to the spectra of the ligands themselves, which is due to the presence of a coordination link. Analysis of the titration curves shows the possible coordination of the ligands in solution in both chelate and non-chelate ways only through the atoms of sulfur of the carbothioamide group with molar ratios M:L=1:1, 1:2 and 1:3. Theoretical quantum-chemical calculations of the IR spectra are carried out; their results are in good agreement with the experimental data of infrared spectroscopy. It is established that cisplatin analogues exhibit a specific cytostatic effect on Allium cepa meristem cells with high antiproliferative activity. Due to the formation of numerous cross-links of metal-containing preparations with DNA molecules and with nuclear proteins, chromatin is not compacting as normal. This results in a disrupted cell cycle, a decreased mitotic index and anomalous cell division, which are usually followed by apoptosis. Palladium-based -complexes cause chromatin dispersion, which leads to significant abnormalities in the processes of karyokinesis, which cause the chromosomes to lose their typical structure and undergo fragmentation, mostly with loss of telomeric sites.

53-58

Authors: O.G. Velychko, Т. Liu, S.O. Abramov, I.V. Marchuk, V.S. Gryshin

The converter lance tips functioning at high external temperatures are damaged in a corrosive environment due to thermal fatigue, hot corrosion, creep, embrittlement and the synergistic influence of all these factors. Premature erosion of the blowing nozzles edges affects the blowing mode. To avoid this effect, certain reliability margins are provided at the stage of the tips design. However, despite this, during the operation of the tips, their premature destruction occurs due to the factors that are difficult to take into account in the initial calculations. The aim of the present work is to solve an important task of increasing the life cycle of the converter lance tips by creating technological methods that allow adjusting the physical-mechanical properties of the surface layer of the outer surface of copper converter lance tips. The developed methods were used for experimental investigations of the energy-power parameters of abrasive blasting treatment process, residual stresses in the coatings and the influence of electrolytic-plasma processing upon a cluster coating obtained by electrospark doping followed by the preparation of an electrolytic-plasma thermal barrier coating. A comprehensive, economically viable and environmentally friendly technological process for the fabrication of the electrolytic-plasma thermal barrier coating on the converter lance tips has been developed and substantiated. This process allows increasing significantly their resistance and thereby improves the steelmaking parameters.

69-76

Authors: A.V. Dubenko, N.V. Nikolenko, A.B. Velichenko, A.D. Suschinskii

The thermodynamic equilibrium in TiO2–SO3–H2O and TiO2–NaF–SO3–H2O systems is studied. It is shown that rutile can spontaneously dissolve in sulfuric acid solutions. However, rutile is considered as an inert component of the titanium-bearing raw material due to the inhibition of such reactions. The kinetic deceleration of rutile dissolution in sulfuric acid is explained by the lability of Ti(IV) cations and the specific features of the rutile crystal structure. The breaking of Ti–O–Ti bonds without additional deformations of the crystal lattice is suggested to be more beneficial when using smaller anions; thus, fluoride ions can be used to this end. The thermodynamic analysis of sulfate-fluoride leaching of titanium confirms an additional decrease in Gibbs energy values for the dissolution of rutile in sulfuric acid in the presence of fluoride ions. A reaction mechanism is proposed for the interaction of rutile with sulfuric acid. The mechanism includes the stage of substitution of oxygen ions on the rutile surface by fluoride ions and the stage of sulfate-acid decomposition of titanium dioxide in places of "defects" of the rutile surface.

96-100

Authors: Y.I. Koltsova, V.V. Peschanskaya

The study was aimed at the preparation of porous layered materials in which each layer differs by volumetric mass and mechanical strength. The combination of product layers with a gradient structure allows purposefully controlling the achievement of required physical-mechanical properties of the synthesized materials. Industrial waste products and natural non-deficient raw materials were used as gas-forming agents to produce multilayer glass-crystalline materials. This contributes to the solution of the problem of waste utilization. The sintering of the samples was carried out at the temperatures of 750 and 850С, depending on the type of a gas-forming agent. The average volumetric mass and compressive strength were determined for the burnt samples. The pore diameter was measured and the coefficient of the inhomogeneous structure was calculated. The type of the formed structure was analyzed, which depends on the average diameter of the predominant pores. It was found that the most optimal structure from the point of view of homogeneity (Kn=0.27–0.39) and low volumetric mass (330 kg/m3) showed the samples that consists of three following layers: a medium one that contained open-hearth slag and two outers ones that contained loam. The compressive strengths of such samples were 3.97 MPa and 2.19 MPa when the load was applied along the layers and perpendicularly to them, respectively. The firing temperature of these materials was 750 ºС.

108-115

Authors: V.К. Lukashov, Y.V. Кostiuchenko, T.M. Shevtsova

The article presents the results of investigation concerning the heat transfer in a liquid film flowing down from a heated vertical surface and evaporating into a cross stream of a neutral (inert) gas. The cross interaction of fluid and gas flows is of interest from the point of view of increasing the intensity of the evaporation process by removing vapor from the surface of the liquid. The presence of a neutral gas above the film allows reducing the vapor pressure of the vaporized liquid in the vapor-gas mixture and, accordingly, gaining the effect concerned at lower temperatures. The investigation was performed using a mathematical model based on physical concepts, which include assumptions about a constant surface temperature and the absence of friction between the film and gas. When developing the model, it was assumed that the motion of the film and the gas stream as well as the heat transfer in them, is an established processes. The heat transfer between the film and gas stream occurs due to both the heat flow transferred by the steam and the heat exchange flow resulted from the contact of the phases. These ideas allowed obtaining differential equations of the heat transfer in a liquid film and a gas phase. By means of the numerical solution of these equations and using the equations that were previously derived by solving the hydrodynamic problem, the equations were obtained, which describe the changes in the temperatures of the film and gas flow along the height of the heated surface and in the temperatures of the gas along the width of the surface. It is shown that the film temperature reaches an equilibrium value when moving away from its initial section. With a further increase in the distance from the section, the liquid can completely evaporate. The developed calculation algorithm allows determining these distances for various initial parameters of the heat transfer process. The results can be used to develop film heat and mass transfer apparatus with cross-interaction of liquid and gas flows.

122-127

Authors: M.N. Meiirbekov, M.B. Ismailov, Т.А. Manko

The effect of polyurethane and silicone rubbers as modifiers providing an increase in the toughness of ED-20 (cold curing) and Etal-Inject-T (hot curing) epoxy resins is investigated. The ED-20 resin has an initial strength of 97 MPa and the impact strength of 20.1 kJ/m2, while Etal-Inject-T resin has an initial strength of 106 MPa and the impact strength of 42.34 kJ/m2. It is established that polyurethane and silicone rubbers equally affect the strength properties of the epoxy resins. The polyurethane rubber was found to be a more effective modifier. The addition of polyurethane rubber to ED-20 resin leads to an increase in impact viscosity, however a slight decrease in the compressive strength is observed. An optimal content of polyurethane rubber in ED-20 resin is about 5%; this ensures a twofold increase in the impact viscosity, the compressive strength being decreased insignificantly (only by 14%). With an increase in the content of modifiers in the ED-20 resin (more than 5%) results in a slight increase in the impact viscosity, however the reduction of the compressive strength becomes significant. The addition of 6.5% of polyurethane rubber to Etal-Inject-T resin causes an increase in both the impact viscosity (by 67% up to 71 kJ/m2) and the compressive strength (by 7.5% up to 114 MPa). When the content of the modifiers in Etal-Inject-T is more than 6.5%, the impact viscosity remains the same, but the compressive strength begins to diminish. An increase in the impact viscosity of the material can be attributed to the formation of a rubber's dispersion phase, which seems to loosen the rigid structure of a cured epoxy resin. The microstructures of the epoxy resin samples modified by polyurethane and silicon rubber were also investigated.

134-139

Authors: L.P. Oleksenko, G.V. Fedorenko, N.P. Maksymovych

Nanosized cerium-containing materials based on tin dioxide with the addition of antimony were synthesized by a sol-gel method and studied as gas-sensitive layers of adsorption-semiconductor sensors intended for measuring the content of hydrogen in air. It was found that the sensors created using the synthesized nanomaterials demonstrated high sensitivity to microconcentrations of hydrogen (44 ppm H2), which may be resulted from a highly dispersive state of cerium and antimony oxides in the formed nanomaterial when introducing them simultaneously in the process of synthesis. It was shown that sensors based on nanomaterial CeO2/SnO2–Sb2O5 have good response time, reproducibility of measurements and a wide range of detecting hydrogen (10–1000 ppm H2). The dependence of the electric resistance of the sensor on the hydrogen concentration in logarithmic scale is linear, which should make cheaper the periodical calibration of the sensor in conditions of its operation. It was observed relatively high selectivity of the sensor to hydrogen measurement in relation to CH4 measurement. The sensors created based on the nanosized CeO2/SnO2–Sb2O5 are promising to measure hydrogen in air because they have twice the sensitivity to Н2 with significantly lower power consumption (P=280 mW) as compared with the sensors prepared by impregnation of a gas sensitive layer with CeCl3 solution (P=450 mW).

148-153

Authors: O.I. Peredriy, I.V. Yemchenko, O.V. Pakholiuk, O.V. Sheginsky

The methods of physical and chemical analysis (complex thermal analysis, X-ray diffraction study, IR spectroscopy and X-ray microanalysis) were used to investigate the effect of heat treatment on the changes in phase composition of the protective coating based on aluminosiloxane polymer filled with Al2O3, ZrO2, TiO2 and kaolin oxides. It is stated that a thermal oxidative destruction of aluminosiloxane polymer with the formation of a reinforcing silicon-oxygen skeleton occurs during the heating of a protective coating to a temperature of more than 573 K. This provides conditions for the formation of a temperature- and fire-resistant layer. The interaction between the components of the coating proceeds at the temperatures of above 1223 K with the formation of mullite and zircon. The introduction of kaolin fiber into the composition during heating from 1223 K causes intense formation of a vitreous phase. The addition of kaolin to the composition of the coating in the amount of 10–20 wt.% increases only the content of the mullite–sillimanite phase by 7–12 wt.%, which leads to an increase in the temperature resistance of the coatings. It is established that the introduction of 1–3 wt.% TiO2 into the coating composition increases the content of sillimanite and zircon phases by 20–25% and 10–12% respectively, as compared to the coatings without titania. In addition, the introduction of TiO2 facilitates the synthesis of the above-mentioned phases and reduces their formation temperatures by 50–60.

162-169

Authors: V.O. Sabierova, Yu.V. Tamarkina, V.O. Kucherenko

This work is devoted to the evaluation of the heat shock efficiency by comparing the properties of solid thermolysis products (STPs) formed from brown coal (BC) during thermoprogrammed alkaline activation (TP-activation) with those formed by activation with heat shock (AHS-process). The sample BC-KOH was prepared by impregnation, the KOH/BC ratio being equal to 1 g/g. TP-activation included heating of BC-KOH (4 deg/min) in argon to a predetermined temperature (150–850C), holding for 1 h and cooling. In the AHS-process, BC-KOH was quickly introduced into a preheated reactor. STPs were isolated by washing (to remove KOH) and drying. The characteristics of STPs supramolecular and porous structures were determined by X-ray diffraction analysis and low-temperature (77 K) nitrogen adsorption. It was found that the STPs yield in the AHS-process is less than in the TP-activation due to the additional formation of volatile organic products. The effect increases with increasing temperature. The yield of STPs was 15% and 24% at 850С (AHS-process) and with TP-activation, respectively. The positive effect of heat shock on the STPs porosity is manifested within the temperature range of 650C to 850C; it becomes more pronounced with increasing the temperature and promotes the formation of STPs with increased specific surface area (an increase from 1115 m2/g to 2414 m2/g), higher total pore volume (by 1.8 times) and increased subnanopores volume (by 2.1 times). At temperatures below 650C, the structural characteristics of STPs are almost identical for both thermolysis modes. The reorganization of supramolecular structure occurs at 400–850C and depends on the heating mode. The interlayer distance of crystallites increases with increasing temperature (from 0.412 nm to 0.453 nm) in TP-activation, whereas it decreases (from 0.412 nm to 0.350 nm) in the AHS-process due to the enrichment of STPs with more structurally ordered crystallites. They have increased linear sizes of graphene layers and are most inert with respect to the action of KOH. In addition, they are uniformly distributed in the STP amorphous porous framework.

178-182

Authors: A.V. Sybir, S.S. Fedorov, M.V. Hubynskyi, S.M. Hubynskyi, S.V. Koval, K.M. Sukhyy, S.M. Foris

The thermal method for the cleaning of carbon materials in an electrothermal fluidized bed belongs to the "green" technologies for producing graphite for the manufacture of anodes of lithium-ion batteries. The technology involves a rapid heating of the feedstock particles to the specified processing temperatures. The aim of the work was to simulate the thermal cleaning of carbon materials in electrothermal fluidized bed and choose such modes for the treatment of natural graphite that will ensure carbon content in the finished product of at least 99.95%. To achieve the goal, a 5 kW laboratory resistive furnace was developed. While processing carbon samples weighing up to 30 g, the reactor simulates the operating conditions that arise during fast heating to 3000°C in a fluidized bed in an inert gas atmosphere. A typical multistage purification cycle in laboratory conditions included the heating of the material during 0.5–1 min and holding it at a constant temperature for 5–15 min. The production mode was controlled based on the dependences of the operating temperature on the power consumption obtained by the "witness" method. The laboratory study of the thermal purification of natural graphite from the Zavallevsky deposit was carried out. The composition of the processed samples was determined by elemental analysis using a spectrometer and by measuring the ash after combustion of the samples. As a result of the study, acceptable parameters of the operating modes were determined, in particular, the temperature of 2900–3100°C and the processing time of 15 min, which ensure the manufacture of high-quality product with a carbon content of at least 99.95%.

189-196

Authors: V.V. Taranenkova, Ya.N. Pitak, G.N. Shabanova

To synthesize special multimineral cements, it is necessary to have information concerning binding properties of individual phases being part of given cements. Despite numerous studies, there are not yet clear theoretical criteria to evaluate the behavior of various oxide compounds (if only qualitatively, not to mention quantitatively) with respect to their possible use in chemistry of special cements. Therefore, the development of corresponding quantitative dependences as well the ascertainment of the physical and chemical conditions determining the binding properties remain the actual task of chemistry of binding materials. Our study shows that a certain range of relative electronegativity values, where compounds under consideration reveal their binding properties, can be determined clearly by means of the concept of electronegativity. It is ascertained that some binary and ternary compounds (about 100) lie within a certain range of relative electronegativity, including those ones which binding properties have not been fully studied yet. Besides, the obtained data will allow selecting the most favorable conditions for compound hardening. Thus, in terms of our findings, the binding properties of oxide compounds and prospects of their application in special cement technology can be evaluated.

202-209

Authors: E.A. Chebanenko, E.E. Martsinko, I.I. Seifullina, V.V. Dyakonenko, S.V. Shishkina

A heterometallic coordination compound {[CuCl(bipy)2]2[Cu2(bipy)2(-C2O4)(-HXylar)2Ge2(OH)2(-HXylar)2Ge2(-OH)2]4Н2О}n (where bipy is 2,2'-bipyridine, C2O42– is the oxalate anion and HXylar4– is the xylarate anion) was synthesized for the first time. It was characterized by the methods of elemental analysis, IR-spectroscopy, thermogravimetry and X-ray diffraction. According to the results of X-ray diffraction analysis, the compound contains one anion [Cu2(bipy)2(-C2O4)(-HXylar)2Ge2(OH)2(-HXylar)2Ge2(-OH)2]2–•and two cations [CuCl(bipy)2]+. Fragment [(-HXylar)2(OH)2Ge2(-HXylar)2Ge2(-OH)2 ] is symmetrical and tetranuclear. Germanium atoms exhibit two different coordination polyhedrons. The coordination polyhedrons of two Ge atoms are distorted trigonal bipyramids. Their equatorial planes are occupied by the two oxygen atoms of carboxyl groups of HXylar4– ligands and the oxygen atom of hydroxyl anion, while the axial positions are occupied by the two oxygen atoms of two deprotonated carboxyl groups of HXylar4– ligands. The coordination polyhedrons of two central Ge atoms are distorted octahedrons formed by four oxygen atoms of deprotonated hydroxyl and carboxyl groups of two HXylar4– ligands and two oxygen atoms of the hydroxoligand. The oxygen atoms of the hydroxoligand form a bridge between two central germanium atoms. The coordination polyhedron for copper in anion [Cu2(bipy)2(-C2O4)(-HXylar)2Ge2(OH)2(-HXylar)2Ge2(-OH)2]2– is a square bipyramid, the top of which is occupied by the oxygen atom of xylaric acid. This leads to the formation of coordination polymer chains [Cu2(bipy)2(-C2O4)(-HXylar)2Ge2(OH)2(-HXylar)2Ge2(-OH)2]n, that interact with each other through hydrogen bonds of water molecules and form layers in the crystal. The cations [CuCl(bipy)2]+ are located between layers of coordination polymer chains. In the cation, copper forms distorted-bipyramidal coordination polyhedron.

215-224

Authors: L.P. Shchukina, Ya.O. Galushka, A.S. Savenkov, A.А. Khlopytskyi

In this work, we studied the stress-strain state of 3D models of structures with different types of pores imitating porous construction heat-insulating wall ceramics by means of the finite element method. It was found that a structure with spherical pores is more durable than the structures with ellipsoidal and globular pores. The wastes of heat-generating facilities (ash sphere, ash and slag and products of its processing) were investigated as prospective pore-forming components for the production of porous ceramics. The chemical composition of the ash was studied and it was determined that they belong to aluminosilicate iron-containing materials, which are classified as low-calcium, low-sulfate and ultra-acidic wastes with liquidus temperatures lying in the range of 1150 to 1700С, which varies depending on the ratio Al2O3:Fe2O3:SiO2. Based on low-melting loam and ash waste (10–30%) at a firing temperature of 970C, porous ceramic materials were prepared and its macrostructural characteristics and properties were studied. It was shown that the use of ash spheres is promising to obtain heat-efficient heat-insulating ceramics. Ash spheres provide materials with high porosity (total 54.2% and closed 31%) at a low level of mechanical strength. This strength is due to the weak interaction of the refractory ash sphere that contains silica and mullite with loam during the firing process, which prevents the formation of strong contact between the sphere and the ceramic matrix. Ash and slag products of its processing can be utilized in the technology of wall ceramics, which is commonly regarded as ineffective with respect to its thermal characteristics (density, thermal conductivity).