Proc. of the Natl. Academy of Sciences of Belarus, Ser. Chemical Sci., 2006, No.3
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Proc. of the Natl. Academy of Sciences of Belarus, Ser. Chemical Sci., 2006, No.3
| Proceedings of the National Academy of Sciences of Belarus
(Vestsi Natsiyanalnai Akademii Navuk Belarusi)
SERIES OF CHEMICAL SCIENCESPublished by The Belaruskaya Navuka Publishing House, Minsk, Republic of Belarus |
Number 3, 2006
CONTENTS
INORGANIC CHEMISTRY
Klyndyuk A. L, Chizhova Ye. A.
Structure and properties of YBa1-xMexCuFeO5+d (Me = Sr, Ca; 0.0<õ£0.4) solid solutions. pp. 5--9
Summary: The influence of partial substitution of barium by strontium or calcium on the crystal structure parameters, thermal expansion and electrical conductivity of YBa1-xMexCuFeO5+ d (Me = Sr, Ca) solid solutions has been studied.
Smolenchuk S. V., Bashkirov L. A., Yanushkevich K I., Bushinskii M. V., Lubinskii N. N.
Crystal structure parameters and magnetic properties of solid solutions of Sr1-xLaxFe12-xÑÎxO19, Sr1-xLax12-xx19 ferrites. pp. 10--15
Summary: Solid solutions Sr1-xLaxFe12-xÑÎxO19, Sr1-xLax12-xx19 (2) are prepared by a ceramic method. Parameters a and c of magnetoplumbite crystal structure are determined for (1) and (2). Their specific magnetization is measured at 77-800 K. It is found that the increase of degree of heterovalent substitution of Sr2+ by La3+ up to x = 0.5 in strontium ferrite SrFe12O19 and of the equivalent amount of Fe3+ by Co2+ or Mn2+ ions results in a nonlinear increase of a and nonmonotonous change of c. For system 1, increasing degree of substitution up to x = 0.5 results in a gradual decrease of specific magnetization, while for system 2, a nonmonotonous change of the parameter takes place. In the systems studied Curie temperature gradually decreases with increasing degree of substitution.
COLLOID CHEMISTRY
Komarov V. S., Seredyuk L. I., Rat'ko A. L.
Active carbons on the basis of sawdust modified with salts. pp. 16--20
Summary: Conditions of formation of porous carbon structure by means of mineral structure formers have been studied. It has been shown that carbons having high sorption capacity and specific surface are formed in the presence of mineral agent particles. Particle size of inorganic pore-former fluences structure of the obtained carbons. The mechanism of carbon structurization by salts decomposing at wood carbonization, conditions of washing inorganic particles from carbon phase and perspectives of this method of active carbon synthesis are discussed.
Komarov V. S., Seredyuk L. I., Rat'ko A. I.
Activation of sawdust in salt solutions in the presence of organic additives. pp. 21--24
Summary: A method of active carbon preparation on the basis of sawdust treated with salt solutions in the presence of organic additives has been elaborated. Sorption capacity of these carbon samples was shown to increase with elevating ZnCl2 content in the modifying solution. It was found that the addition of 5% of methyl alcohol or formic acid and freezing the sawdust together with the modifying solution act in a similar way. Sorption capacity of the modified samples increases 2-2.5 times as compared with the initial ones and is more than 1 cm3/g of carbon. An explanation has been given to the enhanced sorption capacity taking into account cellulose structure and various additive action mechanisms.
ANALYTICAL CHEMISTRY
Kovalevich V. A., Rakhman'ko E. M., Gulevich A. L.
Anion-exchange extraction of inorganic ions with quaternary ammonium salts in the presence of p-trifluoroacetylbenzoic acid heptyl ester. pp. 25--29
Summary: The equilibrium of anion exchange extraction of chloride, bromide, perchlorate, thiocyonate, nitrate ions by trinonylocta-decylammonium 2,4-dinitrophenolate and picrate has been studied. The results on influence of p-trifluoroacetylbenzoic acid heptyl ester additives on conditional exchange constants, solvation constants and numbers are presented. The conditional exchange constants obtained allow selectivity of the extraction process to be evaluated.
PHYSICAL CHEMISTRY
Shutava T. G., Agabekov V. E., Dikusar E. A., Yuvchenko A. P.
Kinetics of thermal decomposition of substituted silver acetylenides in solution. pp. 30--37
Summary: Thermal decomposition of silver acetylenides (AS) RXCºCAg (X = CH2, R = CH3(CH2)6; CH3(CH2)14; CH3(CH2)6C(O)O; C6H5C(O)O or X = C(CH3)2, R = CH3; CH3O; (CH3)3COO) in orto-dichlorobenzene in the temperature range of 338-411 K is an autocatalytic reaction catalyzed by colloidal silver and probably occurring through chemisorbed intermediates. The substitution of the X = CH2 fragment for a C(CH3)2 group significantly increases thermal stability of the compounds in solutions and decelerates their decay. The values of activation energy (Ea) for non-catalyzed AS decomposition decrease with increasing electron-acceptor properties of the substitutes. The difference between the values for non-catalyzed and catalyzed decay is 33-50 kJ/mol. The Ea for catalyzed decomposition of the AS with X = CH2 are 15-20 kJ/mol lower than that for RC(CH3)2C=CAg compounds. Properties of R do not influence quantitative characteristics of catalyzed AS decomposition.
Ivashechkin V. V., Matveyko N. P.
Electrodes with active coatings on the basis of iron, nickel, and cobalt for hydrogen and. oxygen production. pp. 38--41
Summary: The influence of composite electrode coatings of different composition on overvoltage of hydrogen and oxygen release from alkaline aqueous solutions has been investigated for model electrodes covered with layers of iron, cobalt, and nickel obtained with a plasma deposition method.
Makarevich N. A.
Thermodynamic factors in real systems of electrolytes. pp. 42--48
Golub N. M., Borichevsky A. I.
Investigation of the first stage mechanism of hydrolysis of asymmetrically substituted 1,3-dioxans in superacidic media by quantum-chemical methods. pp. 49--52
Summary: Quantum-chemical methods were used to investigate the mechanism of the first stage of catalyzed by acid hydrolysis of asymmetrically substituted 1,3-dioxans. The reaction apparently occurs through alcoxycarbenium ions.
Azizbekyan O. P., Yakimovich M. N., Kacherskaya S. P., Kuvaeva Z. I.
Isoleicine extraction from aminocid mixtures and solvent nature influence. pp. 53--56
Summary: Isoleicine extraction from aqueous salt solutions of corresponding aminoacids by a solution of dinonylnaphtalene sulfonic acid in octane and in a mixed octane-octanol solvent has been studied in a wide range of pH. It has been found that the highest selectivity of the isoleicine extraction is observed at pH 1¸2, while using the mixed solvent.
Petrovich V. A., Volchek S. A., Tabulina L. V.
Effect of hydrogen ions on rhenium reduction rate. pp. 57--61
Summary: In this work, the studies of a rhenium reduction process in rhenium solutions of various acidity are presented. The effect of hydrogen reduction on rhenium film formation as well as the effect of hydroxypolyethylene introduced into the rhenium solution were studied. The rhenium reduction seems to be realized by two mechanisms, one of which is realized in acidic solutions, and another takes place in alkaline solutions. The hydroxypolyethylene additions to the solutions inhibit hydrogen evolution process by: increasing the potential of atomic hydrogen evolving; retarding hydrogen ion diffusion processes; retarding atomic hydrogen association into molecular forms and gaseous state.
Yegiazarov Yu. G., Radkevich V. Z., Khaminets S. G., Potapova L. L, Gorbatsevich M. F.
Activity of metal-coated catalysts on the basis of carbon-fibrous material in the oxidation of CO and H2. pp. 62--66
Summary: Monometallic (Pt, Pd, Ni) and bimetallic (Pt + Sn, Pd + Ag, Ni + Ag) catalysts on the basis of a carbon-fibrous carrier have been prepared and examined in the oxidation of CO and H2. Palladium-based catalysts are the most effective for H2 oxidation, while platinum-based ones - for CO oxidation. Modification of the catalysts with silver and tin leads to a rise of dispersion of the metal phase.
It was revealed that molar ratio of the reactants chemisorbed on the particles of mono- or bimetallic active component is rather essential for catalytic reaction. For the catalysts with the same active metal, it is determined mainly by dimension factor.
ORGANIC CHEMISTRY
Olkhovik V. K., Matveenko Y. V., Vasilevski D. A., Petooshok V. G., Kalechyts H. V.
Synthesis of 4,4'-diformyl-2-alkoxybiphenyls. pp. 67--71
Summary: A preparative method of 4,4-biphenyldicarboxaldehyde and 4,4'-diformal-2-alkoxy biphenyl synthesis starting from dimethyl ester of 4,4-biphenyldicarboxylic acid have been elaborated.
BIOORGANIC CHEMISTRY
Budnikova L. P., Eryomin A. N., Rubinov D. B., Metelitza D. I., Semashko T. V., Mikhailova R. V.
Effect of tralkoxydime on activity of enzyme pairs glucose oxidase - peroxidase and their polyglobular forms. pp. 72--78
Summary: In the mixtures buffer-DMFA the effect of a pesticide, tralkoxydime, on peroxidase-catalyzed oxidation of tetramethyl-benzidine and co-oxidation of phenol and4-aminoantipyrine with participation of enzymes pairs (glucose oxidase Penicillium funiculosum 46.1 (GO) and horseradish peroxidase (HRP), GO and polyglobular HRP (pHRP), co-polymer of polyglobular GO with HRP (pGO-HRP)) has been studied. Tralkoxydime at its concentrations higher than 1.0 mM in different degree activated the oxidation of the peroxidase substrates with participation of the enzyme's pairs which, in accordance with the activation degree, may be disposed in the following manner: (GO - pHRP) > (GO - HRP) >> pGO-HRP. The efficiency of the tralkoxydime action on enzymes increased with pH increasing from 6.4 up to 9.0 and growth of the DMFA content in the water-organic medium.
Litvinko N. M., Kuchuro S. V., Rakhuba G. N., Kalinichenko E.N., Zhernosek E. V.
Effect of etanolamine substrate fragment modification on pancreatic phospholipase A2 activity. pp. 79--82
Summary: The pancreatic pho spholipase A2 activity toward purine nucleoside phospholipid adducts in micellar phase was studied in vitro. It was shown that hydrolysis rate of the conjugate was three times lower than that of natural phosphatidylethanolamine.
PHYSICAL-CHEMICAL PROBLEMS OF ECOLOGY
Vatutsina O. M., Sokol V. P., Soldatov V. S.
Arsenic anion sorption by fibrous composite sorbent as a function of pH. pp. 83--86
Summary: The effect of pH on arsenic anion sorption by a fibrous composite sorbent has been investigated. A sorption maximum for As(V) was observed at pH 5.64, that for As(III) -- at pH 9. The sorbent shows high selectivity toward As(V) and As(III) at pH values typical for drinking water.
TECHNICAL CHEMISTRY AND CHEMICAL TECHNOLOGY
Lishtvan L I., Falushin P. L., Smolyachkova E. A.
Utilization of peat and timber waist for suspension fuel production. pp. 87--91
Summary: The work contains experimental results on elaboration of suspension fuel (SF) production technology on the basis of hard oil products, peat and timber waist. The impact of concentration, moisture, ash-content, particles size and hard phase pouring density on dispersion rehological features and suspension fuel qualitative parameters has been shown.
Trakhimchik O. E., Kuz'menkov M. I.
Hexafluorosilicate magnum synthesis from technical materials. pp. 92--95
Summary: On the basis of a system research of parameters of the technological process of magnesium fluorosilicate preparation from fluorosilicic acids and magnesia usta, their optimum values providing maximal yield of the target product are revealed.
Vorob'ev N. I., Dormeshkin O. B., Shatilo V. I.
Water-soluble chlorine-free NPK fertilizer with controllable balance of nutritious elements. pp. 96--101
Summary: A conversion way of preparation of water-soluble chlorine-free NPK fertilizers with controllable balance of nutritious elements has been investigated. The influence of main technological parameters on the conversion process and product quality has been studied. The optimal technological conditions were determined.
Mozheiko F. F., Korshuk E. F., Potkina T. N., Goncharik I. L
Dressing of deposit phosphorite ores of the Mogilev region. pp. 102--107
Summary: The possibility of dressing Mstislavl's deposit phosphorite ores has been shown. Concentrates suitable for use as phosphorite flour have been produced.
Komar V. V., Pohodina T. A.
Influence of mineral fillers on film-forming properties of powdered epoxy compositions. pp. 108--112
Summary: Experimental results on properties of powdered epoxy compositions filled with various types of modified mineral fillers at curing by acid ic and basic hardeners are presented.
Dyakonov O. M.
Development of the processes of thermal chemical modification of metal wastes. pp. 113--116
Summary: Main questions of metal chip thermal chemical modification during the heating and hot briquetting processes have been studied. It has been shown that the conversion of chemical contaminations into useful products is achieved under continuous heating of the material in an atmosphere with weak oxidized medium created from controlled residues of oil phase. The oil thermal chemical destruction under the air shortage allows to obtain a hydrocarbon atmosphere that prevents the metal from oxidation. The thermal destruction processes of sublimation products lead to formation and adsorption of pyrolytic forms of free carbon on the metal surface. The gas product residues are used for chip heating as fuel additives to natural gas.
Chernaya N. V.
Kinetics of fast coagulation of hydrodispersion of modified tall rosin by cationic polyelec-trolytes. pp. 117--122
Summary: Coagulation kinetics of aqueous dispersion of modified colophony drastically depend on the properties of the cationic polyelectrolyte used, especially its molecular weight. The half-time of coagulation is 15.3-20.0 min for strong polycations and 32.0 min for weak ones. The coagulation ability of PE is higher as compared with aluminum sulfate.
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