V. V. Sidorchuk

Mechanochemical synthesis of BaTiO3 from barium titanyl oxalate

The effect of mechanochemical processing in air and water on the physicochemical transformations of barium titanyl oxalate has been studied using X-ray diffraction, thermal analysis, FTIR spectroscopy, temperature-programmed argon desorption, and particle size measurements. The results demonstrate that mechanochemical processing of barium titanyl oxalate in air leads to the formation of structurally imperfect barium titanate. During subsequent air calcination at 550°C, this material transforms into well-crystallized cubic BaTiO3, whereas thermal decomposition of barium titanyl oxalate only yields cubic BaTiO3 starting at 800°C. Mechanochemical processing in water leads to partial amorphization of barium titanyl oxalate, and conversion of the product to BaTiO3 requires heat treatment at 700°C. All of the BaTiO3 samples obtained via mechanochemical processing have a larger specific surface in comparison with samples prepared by conventional calcination of barium titanyl oxalate or other known processes.

Synthesis of vanadium-phosphorus oxide catalysts deposited onto silica-carbon supports

Effect of conditions of hydrothermal and microwave synthesis of supported vanadium-phosphorus oxide catalysts in an aqueous medium on the physicochemical properties of the vanadyl hydrophosphate obtained was studied. The transformations occurring in the system were examined using X-ray phase and differential-thermal analyses, adsorption-structural method, and scanning electron microscopy.

Formation of Porous Vanadium- and Molybdenum-Containing Oxides during Mechanochemical Activation of Pore-Free Powders

Porous V- and Mo-containing oxides have been produced by mechanochemical processing of pore-free coarse powders in different environments: air, water, and ethanol. The materials have been characterized by nitrogen adsorption-desorption measurements, mercury porosimetry, scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The results demonstrate that the only effect of air milling is to reduce the particle size of the powders, whereas wet milling leads to the formation of meso- and macropores with several maxima in the pore volume-size distribution.

Hydrothermal modification of silica in the form of a hydrogel-xerogel

The influence exerted by the conditions of hydrothermal treatment of silicas in the form of a gelxerogel on the pore structure and mechanical properties of the adsorbents obtained was studied.

Specific features of the photocatalytic destruction of Safranin T on mechanochemically produced barium titanate

Possibility of producing powdered barium titanate with increased specific surface area and defective structure by mechanochemical treatment of barium titanyl oxalate and a mixture of barium and titanium oxides was studied. Samples were examined by means of X-ray phase and differential-thermal analyses, low-temperature nitrogen adsorption, EPR, and electronic absorption spectroscopy. The photoactivity of the mechanochemically activated powders in the reaction of Safranine T disintegration in aqueous solutions was analyzed.

Synthesis of H3PW12O40 based heteropoly compounds chemically fixed on silica surface

Possibility of activating the silica surface for chemical fixation of tungsten heteropoly compounds of the 12th series on its surface was analyzed.

Production of microspherical aerosilogels by spray drying in a superheated steam

The effect of spray drying of aerosil dispersions in a superheated steam on the formation of microspherical grains and their pore structure was studied.

Changes in the pore structure of silica in chemical modification with organic compounds

Changes in the pore structure of silica adsorbents in their chemical modification with organic compounds of various kinds by gas-and liquid-phase processes, as well as those under conditions of high pressure of the reagents, were studied.

Hydrothermal deposition of vanadium phosphates onto carbon materials

Vanadium-phosphorus oxide compounds of various chemical and phase compositions were synthesized by hydrothermal and microwave techniques on the surface of carbon materials (activated carbons, nanotubes, graphite). The composites obtained were studied by means of X-ray phase and differential-thermal analyses, nitrogen adsorption, and scanning electron microscopy.

Specific features of modification of activated carbons with steam and hydrogen peroxide vapor at high temperatures and pressures

The effect of high-temperature treatment of activated carbons with water and hydrogen peroxide solutions on their pore structure, surface structure, and adsorption properties was studied.