Volodymyr Sydorchuk

Sol-gel synthesis and properties of compositions containing heteropoly compounds in porous silica matrix

Compositions containing heteropoly compounds (ammonium phosphoromolybdate (APM) and phosphoromolybdenum acic (PMA)) are synthesized in a porous silica matrix using the sol-gel method. The obtained compositions containing 5–20 w/w % of APM and PMA are studied with the help of the X-ray-phase and differential-thermal analyses, IR and electron spectroscopy, and nitrogen adsorption. The APM and PMA maintain the Keggin structure after being introduced into an oxide matrix. The samples prepared by the sol-gel method have mesoporous and meso-macroporous structures and enhanced photocatalytic activity in comparison to the initial heteropoly compounds.

Mechanochemical degradation of Safranin T catalyzed by oxides

Mechanochemical treatment of aqueous solutions of Safranin T in the presence of oxides as catalysts was studied.

Physical-chemical transformations in the system V2O5/(NH4)2Mo2O7 under hydrothermal conditions

AbstractModified compositions in the system V2O5/(NH4)2Mo2O7 have been prepared by means of mechanochemical, hydrothermal, microwave and ultrasonic treatments in aqueous medium. Chemical and phase transformations occurring on the stages of modification and following calcinations have been studied with the help of XRD, DTA-TG, FTIR and UV-Vis spectroscopy, nitrogen adsorption, and SEM. It has been established that precursors of catalytically active phases possessing meso-macroporous structure have been formed during modification. The comparison of the properties of compositions prepared via different methods has been carried out. Particularly, precursors modified via various procedures possess different morphology.

Electokinetic and adsorption properties of different titanium dioxides at the solid/solution interface

AbstractSix samples of titanium dioxide of different phase compositions and specific surface areas have been characterized by XRD, Raman-and FTIR spectroscopy, adsorption of nitrogen, electrophoresis. Adsorption of Zn(II) ions at the TiO2/NaCl aqueous solution interface as well as the effect of adsorption on the structure of electrical double layer have been studied. The influence of ionic strength, pH and presence of ions on the adsorption of Zn(II) ions at the TiO2/NaCl solution interface have also been investigated. The zeta potential, surface charge density, parameters of adsorption edge pH50% and ΔpH10–90% for different concentrations of basic electrolyte have been determined. Studied unpurified samples showed lower values of isoelectric point pHiep compared with literature data due to the presence of anion impurities. The antibate dependence between pHiep values and particle size has been established. Adsorption of Zn(II) ions using monophase samples is completed at a lower pH than for the biphase TiO2. Appearance of the point CR3 is associated with the charge turnover from positive to negative at high values of pH and formation of Zn(OH)2.

Mechanochemical synthesis of BaTiO3 using different forms of TiO2

Reactions between barium oxide and different forms of titanium dioxide during milling in air and subsequent heat treatment have been studied by X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The results indicate that, when the low-temperature forms of TiO2 are used, milling produces weakly aggregated barium titanate powders with a large specific surface area.

Mechanochemical synthesis and some properties of dispersed lithium niobate

Interactions in the lithium carbonate-niobium pentoxide system upon mechanochemical treatment (MChT) in air and in water are studied. The products are examined using differential thermal and X-ray diffraction analyses; IR, Raman, and electron spectroscopy; nitrogen adsorption; and electron micros-copy. Activation of the reagents and direct mechanochemical synthesis of lithium metaniobate (LMN) were found to occur at 600–850 and 1000 rpm, respectively. Lithium metaniobate prepared by MChT has high dispersion, defect structure, and increased photocatalytic activity.

Preparation and properties of BaTiO3/porous oxide composites

Barium titanate has been synthesized in pores of oxide matrices using barium titanyl oxalate and barium titanyl peroxide (peroxotitanate) by a sol-gel process and by dispersing the precursors together with pyrogenic oxides in water. The composites were characterized by X-ray diffraction, differential thermal analysis, nitrogen adsorption measurements, transmission electron microscopy, dielectric spectroscopy, and photocatalytic activity measurements. The results demonstrate that the pore structure of the composites forms concurrently with their crystal structure. The composite produced using pyrogenic alumina has high dielectric permittivity.