Close to spherical nanosized niobium diboride particles with an average diameter of 65 nm were synthesized by the reaction of amorphous boron with niobium powder at 1073 K in an argon atmosphere in KCl and Na2B4O7 ionic melts (autoclave, argon pressure of 4 MPa, 32 h).

— A new technique has been proposed for TiO 2 synthesis via oxidative hydrolysis of TiN powder. We have examined the effect of factors determining the rate of TiN dissolution (temperature, concentration, and nature of the oxidant) on the phase composition and particle size of resulting TiO 2 powders and assessed the photocatalytic activity of the synthesized powders in comparison with commercially available photocatalysts.

The product composition of photocatalytic oxidation of vaporized sevoflurane, a next-generation fluorinated inhalation anesthetic, has been studied. It has been found that the final products of oxidation are carbon dioxide and hydrogen fluoride. The possibility of complete chemical absorption of the evolved hydrogen fluoride by a lime absorber during the course of the photocatalytic reaction has been shown. A safe scheme for using photocatalysis is recommended for purifying air to remove vapors of halogen-containing anesthetics under medical hospital conditions.

Products of oxidation of HfB2 particles with mean size 50–55 and 20–25 nm with air oxygen under polythermal and isothermal conditions have been studied by means of thermal analysis, scanning electron microscopy, X-ray energy-dispersive analysis, and elemental analysis. Rate constants of oxidation of the HfB2 nanoparticles have been determined.

We have studied reaction between ZrCl 4 and NaBH 4 at temperatures between 300 and 725°C. The results demonstrate that single-phase zirconium diboride nanoparticles are formed starting at 575°C. According to electron microscopy data, the ZrB 2 powder obtained at 575 and 725°C consists of variously shaped particles, some of which are almost spherical, ranging in diameter from ~10 to 20 and from 25 to 35 nm, respectively. These values agree with the equivalent particle diameters evaluated from the measured specific surface area of ZrB 2 , ~14 and ~32 nm, respectively, and with the crystallite size extracted from X-ray diffraction data: D hkl ~ 13 and 28 nm.

Products of the zirconium powder reaction with amorphous boron in a Na2B4O7 ionic melt at 650–850°C and those of the ZrCl4 reaction with NaBH4 at 300–725°C have been studied by means of X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry, and elemental analysis. At temperature ≥750°C, single-phase ZrB2 with the particle size of 60–80 nm is formed in a Na2B4O7 ionic melt, whereas the ZrB2 powder obtained via the reaction of ZrCl4 with NaBH4 at temperature ≥575°C consists of particles differing in the shape, some of which are close to spherical with diameter of 10–35 nm.

The preparation of nanosized Group IV metal diborides by reacting powdery titanium, zirconium, and hafnium with fine-grained boron in Na 2 B 4 O 7 ionic melts in the temperature range 600–850°C has been studied. Nanosized titanium, zirconium, and hafnium diborides are formed at temperatures of at least 750°C.

TIOKRAFT experimental photocatalytic recyclers are suggested for cleaning and disinfection of indoor air in various facilities, including hospitals. It is demonstrated that these recyclers can be effectively used to purify air from volatile organic pollutants, aerosols, and fungal and bacterial microflora. The photocatalytic recyclers reduce microbiological contamination of the air in hospital facilities by an order of magnitude. Thus, the recyclers can be considered as promising agents of protection against nosocomial infections.

The method of the superadiabatic filtration combustion provides means for efficient extraction of at least 70% of the metal from oil residues with minimum cost, as well as for the environmentally safe disposal of the hydrocarbon residue to heat generate. This is due to the autolocalization of the reaction zones in a particular zone of the reactor observed in the superadiabatic filtration combustion mode. The potential of the method was shown for molybdenum-containing heavy oil residues. (C) 2015 Elsevier Ltd. All rights reserved.

X-ray diffraction analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry, and elemental analysis have been applied to study the products of interaction of powder hafnium with fine-crystalline boron in the Na2B4O7 ionic melt at 600–850°C and of HfCl4 with NaBH4 at 300–700°C.

The possibility of recovery of zinc and zinc-containing compounds from real technogenic waste, metallurgical sludge containing about 1.0% zinc by a filtration combustion method was studied. This method due to its features is distinguished by low energy consumption and can be effectively applied in cases where the use of traditional methods is economically unjustified. In a wide range of control parameters conditions of combustion of slurry samples, the degree of extraction of zinc-containing products were found. The optimal process conditions were determined, under which recovery of zinc from poor sludge (∼1.0% Zn) was possible.

Nonpyrophoric tungsten powders with an average particle size of about 30 nm were obtained by pyrolysis of tungsten hexacarbonyl in a flow of microwave discharge nitrogen plasma. It is found that these powders are stable in air up to 300°C. The reason for such stability is that the structure of powder particles is of the core-double shell type, in which the metal core is covered with an oxide film approximately 1 nm in thickness, coated in turn with roentgenoamorphous layer consisting of carbon, oxygen, and nitrogen atoms. It is also established that the powders under investigation mainly release carbon oxides (CO and CO 2 ) and water into the gas phase upon heating in vacuum. Among the molecules present in the gas phase in small concentrations, nitrogen monoxide (NO) and formaldehyde (H 2 CO) are worth mentioning apart from C1–C3 hydrocarbons.