Home – Home – Jornals – Chemistry for Sustainable Development 2004 number 5

The results of the geological, physicochemical, and technological studies of mineral coals of the Tyva region are presented. Directions of high-level comprehensive processing of coals, which ensure the development of economy and raise the living standards of the population of the Tyva Republic, are shown.

Conditions of phenol oxidation with hydrogen peroxide have been studied using a slot type flow electrolyzer with a gas-diffusion electrode to generate hydrogen peroxide from oxygen. The dependences of the rate and efficiency of phenol oxidation on current density have been investigated (pH 12-13). The efficiency factor of a flow type electrochemical cell has been determined.

This paper presents the results of interlaboratory comparison of analytical data on ion composition for two artificial rain and 80 atmospheric aerosol samples taken on AFA-KhA and Whatman filters. The largest error of analysis is reported for the HCO₃^- and NH₃⁺ ions. Optimization of the water extraction procedures and improvement of water used for this purpose will reduce the systematic error in aerosol analysis.

This paper presents a comparative analysis of the contents of heavy metals (HM) in the water, suspended matter (SM), and bottom sediments (BS) of the Ob river based on the results of long-term monitoring. The spatial distribution of metals along the middle and lower course of the Ob river is affected by its large tributaries such as Tom', Chulym, and Irtysh and by the Novosibirsk reservoir, as well as by large cities (Novosibirsk, Tomsk, and Nizhnevartovsk). The metal distribution at the interface between water and bottom sediments depends on the hydrological and hydrochemical conditions and is the major factor that is responsible for the higher contents of heavy metals in the bottom sediments of the Novosibirsk reservoir compared with the channel and still water lines of the river. The calculated concentration factors depend on the nature of the metal; the least factors were obtained for lead and zinc. Previous data obtained for the Ob reservoir and the upper Ob in general are discussed.

Methods for utilization of liquid and solid wastes of soda production are reviewed. The possibility of flooding oil fields with distiller fluid is examined. A landfilling technique is described whereby distiller fluid is injected into deep horizons. Utilizations of distiller fluid in asbestos-cement and white black productions are discussed. From soda production sludge one can manufacture building materials and oil-well cement materials for cementing wells under stringent mining and geological conditions.

Four topological structures of polytetrafluoroethylene (PTFE) have been found by using thermomechanical spectroscopy (TMS): amorphous structure and three crystalline (high-melting, intermediate, and low-melting) modifications. Gamma irradiation of PTFE showed that both free volume and molecular mass remain practically unaffected in the pseudoreticular structure of the amorphous block. In the crystalline phase, gamma irradiation reduces the molecular weight of the crystallized chains of the low-temperature modification; the intermediate and high-temperature crystalline phases disappear as a result of their transformation into the amorphous structure. Quantum-chemical simulation of the F₃

Quantitative and comparative analysis of the activity of 3,6-bis(vinylsulphonyl)-1,2,4,5-tetrafluorobenzene and 3,6-bis(vinylsulphonyl)-1,2,4,5-tetrafluorobenzene in radical copolymerizations with styrene has been carried out. 3,6-Bis(vinylsulphonyl)-1,2,4,5-tetrafluorobenzene possesses high reactivity in radical reactions due to the effect of the tetrafluoro-substituted benzene ring as an acceptor substituent on the vinyl groups of the monomer.

Ultradisperse tetrafluoroethylene powder obtained by thermo-gas-dynamic method (FORUM TM material) was studied by derivatography, mass spectrometry, and differential scanning microcalorimetry. Thermal decomposition of FORUM and its thermophysical properties differ significantly from those of commercial PTFE. The temperature range of decomposition increased more than fourfold: 465-595^oC for PTFE, and 70-550^oC for FORUM. Thermal decomposition of FORUM gave a wide spectrum of molecular fragments with atomic weights from 31 up to 881. In the crystalline phase, there are no phase transitions characteristic of commercial PTFE samples; at the same time, the melting and transformation points in the amorphous part of the polymer are shifted.

Glow discharge polymerizations of fluorobenzenes, perfluoromethylbenzenes, polyfluorostyrenes, and perfluorinated benzocycloalkenes have been studied. The reactivity of these compounds depends on the number and position of fluorine atoms in the ring and on the type of substituent. High reactivity is inherent in compounds with a fluorinated vinyl group and in ortho-substituted compounds (perfluoro-o-xylene, perfluorobenzocyclobutene). The polymer products were identified by IR spectroscopy and element microanalysis. Film growth rates on metallic supports have been determined. Suggested mechanisms underlying polymerizations are discussed; these include double bond polymerization, condensation of fluoroaromatic rings via elimination of substituent, and ring cleavage that forms aliphatic segments in the polymer chain. Introduction of chlorine atoms in the starting compound decelerates polymer formation. The polymerizations are accompanied by oxidations, leading to oxygen-containing groups in the polymers. Polymerizations of oxygen-containing compounds C₆F₅OR (R = CH₃, CF₂H, CF₃) and C₆F₅C(O)CH₃ have been investigated, and film growth rates have been determined; routes of transformations of oxygen-containing substituents are suggested. For a number of polymers, hydrophobicity and thermal stability are assessed.

Solid-phase mechanochemical methods for the synthesis of new materials, metal-fluoropolymer and metal-ceramics-fluoropolymer composites have been developed. Composite materials possessing high electric conductivity, low friction coefficient and mechanical attrition resistance were synthesized from W-Cu, WC-Cu, and Cu-TiB₂ and ultrafine polytetrafluoroethylene (UPTFE) systems. It is demonstrated that thermal stability of mechanically processed pure UPTFE differs from that of the PTFE component of mechanocomposites and depends on the nature of the main component of the composite.

The results of investigations into new wear-resistant polymer composites based on polytetrafluoroethylene filled with disperse synthetic and natural compounds are presented. The efficiency of using similar fillers in the crystalline polymers is shown, which cardinally modify the polymer properties. The materials developed have passed field tests as the components of friction units of equipment that are functioning in conditions of the North and process equipment of mining industry. Their application allowed the resource of friction units to be raised manyfold and also the problem of import substitution for regular seals and bearings to be solved.

Pyrolysis reactions of polytetrafluoroethylene (PTFE) proceeding under various conditions and giving rise to perfluoroolefins and perfluorocyclobutane together with perfluoroalkanes, perfluorocyclopentenes, and perfluoromethylbenzenes are considered. Methods for the preparation the simplest homologs of perfluoroarenes, namely, perfluoromethylarenes with one to three trifluoromethyl groups (perfluorinated methylbenzenes, methyldiphenyls, methylnaphthalenes, methylindans, and methylpyridines) by co-pyrolysis of PTFE with perfluoroarenes have been developed. Data on co-pyrolysis of chloropentafluorobenzene with PTFE generating perfluoromethylbenzenes, chloroperfluoromethylbenzenes, and perfluoroindan are considered. Routes involving difluorocarbene and leading to perfluorocyclopentenes, perfluoromethylarenes, chloroperfluoromethylbenzenes, and perfluoroindan are discussed.

The fundamental features of direct fluorination of polymers and its potential commercial applications are described. The effects of the composition of the F₂-He-N₂-O₂-HF fluorination mixture, fluorine pressure, temperature, and fluorination time on the formation rate and chemical composition of the fluorinated layer, as well as on the density, refractive index, surface energy, gas separation characteristics, and friction coefficient of the latter have been studied. Processes of formation and destruction of the long-lived and short-lived radicals, which are involved in the chain processes of the direct fluorination, have been investigated.
A description of the commercial applications of direct fluorination to improve some performance characteristics of polymeric articles is given. Among these characteristics are the selectivity of gas separation of polymeric membranes, barrier and adhesion characteristics.

Meteorological effects on the ionic composition of atmospheric aerosols and precipitates in West Siberia have been studied. Seasonal variations have been found: decreased mass concentration of aerosol particles, increased contents of water-soluble salts in them, and changes in the proportion of ions originating from the volatile components of the atmosphere or the land or ocean surface (in aerosols and precipitates); these changes were also observed in relation to the periodicity and amount of precipitates. Increased concentrations and fractions of Ca²⁺ + Mg²⁺, Na⁺, and ions in southwestern Siberia correlate with the trajectories of air mass transfer from the territory of Kazakhstan and from the Aral and Caspian Seas. In northwestern Siberia, the effects of remote land sources are weaker, while marine source effects are more pronounced, the major precursors of ions in aerosols being the volatile components of the atmosphere.