N. B. Egorov

Preparation of lead sulfide nanoparticles in the photolysis of aqueous solutions of lead thiosulfate complex

It was found from spectroscopic and microscopic data that lead sulfide nanoparticles are formed during the UV irradiation of aqueous solutions of lead thiosulfate complex. The yield and the size of the lead sulfide nanoparticles depend on the concentration of solution and the lead to thiosulfate ion ratio in the solution.

Separation of rare earth elements by zone recrystallization

The separation of holmium and cerium by zone recrystallization using a mixture of HoCl36H2O and CeCl36H2O was investigated. It is shown that holmium is enriched at the end of the crystal that the recrystallization zone moves to, while cerium is concentrated in the primary solidification zone. The possible reasons for the experimentally observed distribution of hydrated ions of cerium and holmium along the length of the ingot are discussed. Also the coefficients of enrichment and separation are calculated.

Products of photolysis of cadmium thiosulfate aqueous solutions

On the basis of X-ray diffraction and chemical analysis data, it was found that cadmium sulfide exhibiting the ‘size effect’ is formed during the UV irradiation of aqueous solutions of cadmium thiosulfate. Sulfate ions and hydrogen ions accumulate in the aqueous solution. It was shown that the yield of cadmium sulfide is affected by the concentration of thiosulfate ions in the solution. The overall equation of photolysis of cadmium thiosulfates is proposed.

Investigation of lead thiosulfate photolysis in aqueous solutions

A model of photolysis of PbS2O3 aqueous solutions has been proposed on the basis of identified photolysis products and semiempirical quantum-chemical calculations. The degradation of PbS2O3 starts with the dissociation of the sulfur-sulfur bond in the thiosulfate group via photochemical excitation and transition of the system a whole to the activated state, which is decomposed by the solvent. The interaction of the primary photolysis products with PbS2O3 results in the formation of final products.

Synthesis and properties of lead nanoparticles

Lead nanoparticles were synthesized by the thermal decomposition of lead stearate in octanol. The nanoparticles were characterized by X-ray powder diffraction, thermal analysis, IR spectroscopy, and electron microscopy. The lead particle size can be controlled by both varying the concentration of lead stearate in octanol and changing the thermolysis time. Lead nanoparticles have an organic coat composed of decomposition products of lead stearate. This coat prevents the particles from oxidation in air and favors their dissolution in organic solvents.

Quantum chemical study of the structure and properties of isotopically pure lead chalcogenides

In the present work the theoretical methods B3LYP/SDD, GGA and BP86/TZ2P were used for quantum-chemical calculations of lead chalcogenides. It is shown that these levels of theory are applicable for assessment of their geometric parameters, Raman and IR spectra and thermodynamic characteristics. It is shown that there are correlations between the experimental and calculated characteristics of lead sulphide, selenide and telluride. The influence of different isotopes of lead, sulphur, selenium and tellurium on the thermodynamic parameters and the Raman spectra for the lead chalcogenides is shown.

Study of photolysis of K 4 [Cd(S 2 O 3 ) 3 ] solutions in aqueous isopropanol

Photolysis of K4[Cd(S2O3)3] solutions in aqueous isopropanol under irradiation with high-pressure mercury-quartz lamp has been studied by spectroscopy methods. The photolysis products have been identified by X-ray diffraction analysis; their formation mechanism has been suggested. The primary photolysis product is nanosized CdS, its irradiation initiating further redox transformations of the solution components to give the final products.

Thermolysis of Lead Thiosulfate Thiourea Complexes

We have studied the thermolysis of lead thiosulfate thiourea complexes in a nitrogen atmosphere at temperatures from 20 to 500°C. The thermal decomposition products have been characterized by X-ray diffraction, IR spectroscopy, and mass spectrometry at different stages of the process. The structure of the complexes and the thermolysis mechanisms are discussed.

On the Photolysis of Barium Thiosulfate

The synthesis of BaS2O3 ⋅ H2O was carried out in accordance with a published procedure [6]. A solution of BaS2O3 with a concentration of 7.5 × 10–3 mol/L and a volume of 40 mL was irradiated with the full light of a DRT-240 high-pressure mercury-vapor lamp for 40 min at room temperature. The resulting precipitate was separated from the solution by centrifugation, triply washed with water and then with ethanol, and dried in a vacuum desiccator. The precipitate preparation procedure was multiply repeated to accumulate an amount sufficient for analysis. The concentrations of barium ions before and after photolysis were determined on an ICAP 6300 Duo atomic emission spectrometer. The diffractograms were recorded on a Rigaku Miniflex 600 diffractometer. The IR spectra were measured on a Nicolet 6700 Fourier transform IR spectrometer in a range from 400 to 4000 cm–1. The samples were prepared as pellets with KBr. The values of pH were measured on an inoLab pH/Ion 740 WTW ion meter with the use of a Sentix 81 combined electrode. The diffractogram of the precipitate obtained by photolyzing aqueous BaS2O3 solutions contained only lines due to the BaSO4 phase (PDF 01-072-1390). An IRspectroscopic study of the precipitate showed that the IR spectrum contained absorption bands at 1170, 1117, 1074, 997, and 611 cm−1, which are characteristic of BaSO4. Furthermore, the sediment exhibited absorption bands at 925, 635, and 497 cm−1 characteristic of BaSO3 and absorption bands at 686, 556, and 540 cm−1 characteristic of BaS2O3. The intensity of the absorption bands of BaSO4 was considerably higher than that of absorption bands due to BaSO3 and BaS2O3. The treatment of the photolysis product of BaS2O3 solutions, which was separated by centrifugation, with n-hexane showed that the electron spectrum of the extract did not contain absorption bands characteristic of dissolved elemental sulfur. Its absence from the solid-phase products of photolysis is a distinctive feature, as opposed to the products of photolysis of the aqueous solutions of lead thiosulfate [7]. It was organoleptically revealed that the UV irradiation of the air-saturated solutions of BaS2O3 was accompanied by the release of sulfur-containing gas. The gas released during the photolysis of a BaS2O3 solution was transferred into a receiver by passing air through the solution and analyzed with the aid of a TRACE DSQ gas chromatography–mass spectromeSHORT COMMUNICATIONS PHOTOCHEMISTRY

Preparation of nanosized nickel powder by direct-current electrolysis combined with high-voltage spark discharge

The possibility of obtaining nanosized nickel powder by simultaneous dc electrolysis and high-voltage spark discharge has been explored. The powder has been prepared from a nickel sulfate-containing electrolyte using soluble nickel anodes at a cathodic current density in the range of 11000–19000 A/m2, a voltage on the spark gap of 12–16 kV, and a pulse repetition frequency of 0.5 Hz. The effect of various factors on the synthesis of the powder has been studied and the optimum conditions for its preparation have been found using mathematical experiment design. The size distribution of particles has been determined with a particle size analyzer. The BET specific surface area of the powder has been measured to be 11.7 ± 2.1 m2/g.