Home – Home – Jornals – Chemistry for Sustainable Development 2005 number 3

The most interesting results among those described in literature on the development and application of the materials for adsorption purification of water from petroleum and oil products are considered and generalized. Sorbents used both for elimination of oil outflow and for purification of oil-containing waste water are considered. Natural (plant- and mineral based), artificial and synthetic sorbents are described. Fibrous (non-woven, in the form of chaotically positions fibers, wool, pressed, etc.) materials are considered along with those used in the dispersed or granulated form. It is stressed that combination of materials differing both in origin and in the state of aggregation, with additional modifications if necessary (for the purpose of enhancing the actual properties or imparting new characteristics) leads to a multiple increase in the efficiency of purification process.

Formation of Al(III)-maltol complexes was studied in aqueous solutions. It was shown that an increase in pH resulted in sequential transformations of the complexes in the following order: [AlMa]²⁺, [AlMa₂]⁺ and [AlMa₃]. The data concerning stability constants revealed the superior stability of the electrically neutral complex (formed at pH 4-8), which is also of interest regarding its application in medicine.

Results of electrochemical research of the formation mechanism of metal-containing modifying agent for polyurethanes in the systems like

Results of the research into improved techniques to excrete the extracts of biologically active betulin, suberic and tanning agents from the wastes of birch bark are presented. A short-term activation of bark by superheated steam has been used to intensify the processes of excretion of extractives. Selection of optimum conditions for bark activation that ensure the maximum yield of betulin, suberic and tanning agents has been performed. It has been shown that the use of betulin extracts is viable to yield gastroprotective preparations, whereas the use of suberic materials is viable in production of film-forming materials.

Optimization of conditions for obtaining of tanning agents, anthocyanidin dyes, and enterosorbents from bast of a birch bark has been performed. By choosing the appropriate conditions for alkali treatment of a porous fixed residue from extraction processing of bast, enterosorbent was produced, which has exhibited high efficiency when treating acute intestinal infections in animals and dysbacterioses that were caused by application of antibiotics. The comprehensive processing of bast of a birch bark makes it possible to produce about 3 % of resinous matter, 35-40 % of polyphenolic products, 13-15 % of anthocyanidin dye, and about 40 % of enterosorbent.

The composition of extractives from the top part of Halenia corniculata were investigated. Two individual compounds were extracted and characterized.

Using sweet and sulphurous oils of West Siberia as an example, the regularities in chromatographic isolation and separation of sulphur compounds (SC) with the use of tin tetrachloride have been studied for the first time. It has been demonstrated that the efficiency of SC separation depends on the content of total sulphur in oil. The high extent of decontamination of the studied oils from SC is achieved: 72-95 % with respect to total sulphur and 68-95 % with respect to sulphide sulphur. Most part of SC is isolated with benzene chromatographic fraction irrespective of sulphur content of oil, of Pr/Ph ratio, and of geological confines of a reservoir. Sulphur compounds of the studied oils are presented by thiophenes and sulphides. Oils with 0.22-0.68 mass % of the total sulphur are dominated by alkyl-substituted thiacycloalkanes among sulphides and by alkyl-substituted dibenzothiophenes among thiophenic compounds. Oils with 0.94-1.14 mass % of the total sulphur are dominated by alkylbenzothiacycloalkanes and alkylnaphthenodibenzothiophenes.

The uniformly disoriented carbon fibre with textural blocks about 0.5 nm in size is produced from the pitchy fibre that was moulded in an electrostatic field from a melt with a moulding temperature T_m that exceeded the softening point T_s by 70^oC. The layered carbon fibre with the ordered shell and disoriented nucleus is produced from a pitchy fibre through its mechanical draft at T_m that exceeds T_s by 40^oC. The average size of textural blocks in it is of about 1.0 nm.

Properties of aluminium oxyhydroxides (AOH) that were obtained through oxidation of electroexplosive ultradispersed (nano-) powder of aluminium by water (55^oC) and subsequent calcination of the initial sample in a temperature range 100-1150^oC have been investigated. These materials were taken up as highly effective adsorbents for special complex water treatment. With the use of X-ray diffraction, thermal analysis, and porosymmetry methods, the basic structural characteristics of samples have been determined. It was found that initial AOH contains two modifications: pseudo-boehmite and bayerite. Depending on conditions of heat treatment, the following phase transitions are observed: bayerite → η-Al₂O₃ → θ-Al₂O₃ → α-Al₂O₃ and pseudo-boehmite → γ-Al₂O₃ → δ-Al₂O₃ → θ-Al₂O₃ → α-Al₂O₃. The oxyhydroxides that were obtained at relatively low calcination temperatures are characterized by high specific surface and by existence of a microporous structure. A decrease in the calcination temperature leads to disappearance of micropores and to an increase in the volume and size of mesopores.

The process to obtain lithium metatantalate, lithium and sodium metaniobates and their solid solutions, lithium-conducting phosphate solid electrolytes, epitaxial films of lithium metatantalate and metaniobate, and Li_1.3Al_0.3Ti_1.7(PO₄)₃ solid electrolyte on various substrates with the use of their precursor peroxide solutions has been studied.

Various methods for recovery of birch bark processing wastes to produce energy, carbon sorbents, biological products, and humic substances have been investigated. Optimum ways for combustion of fixed residues from extraction processing of a birch bark, which differ in moisture and ash content, have been determined by means of calculations. Clearing of a part of bast pores in the birch bark during recovery of extractives is favourable to form the developed cellular structure after carbonization and subsequent activation of bast. The produced sorbents match commercial powder sorbents, which are made from qualitative wood, with respect to their performance. Selection of cultivation conditions is performed for fungi of Trichoderma species on bast of a birch bark, these conditions providing the production of biological preparations with nutrition from ammonium nitrogen and the production of humic substances with nitric nitrogen used.

For the first time MgB₂ and MgCu₂ were synthesized utilizing a dynamic loading technique. Particularly magnesium diboride is of great importance due to its superconducting properties. X-ray and electron microscopy analyses were carried out in order to characterize the products of the reaction. The method described can be used to produce pure MgB₂.

The possibility of processing natural and industry-caused materials by carrying out mechanochemical reactions participated by the material of milling bodies is investigated; this possibility is based on the use of abrasive (desirably amorphous) inert additives, such as glass or fused quartz. The essence of the method is the abrasive-reaction wearing of the material of milling bodies of the mechanochemical reactor. Meta-oxide-sulphide composites (during the treatment of tenorite and galena) and composites based on pyrite and quartz (during mechanical activation of a mixture of sulphur and amorphous quartz) were obtained in a planetary AGO-2 mill with steel equipment.

Effect of air industrial emissions of the main industrial hubs of Buryatia on the pine forests in water-collecting area of the Lake Baikal has been studied. Contamination of forest stands is estimated from accumulation of sulphur, a priority pollutant element, in needles of Scotch pine. Depending on the distance from sources of industrial emissions, zones of variable intensity of forest pollution are distinguished. The highest correlations between the sulphur content of needles and morphometry parameters of trees are revealed in the zone of severe pollution.

The procedure has been developed to determine arsenate, arsenite, monomethylarsonate, and dimethylarsenite ions in water by the capillary electrophoresis method with spectrophotometric registration of detectable forms of arsenic derivatives. Isopolymolybdate has been selected as a reagent for derivatization. The stoichiometry has been studied and the extinction coefficients of the detected heteropoly complexes have been determined. Optimum conditions for their formation and for electrophoretic separation have been selected. Upon concentrating by the electrostacking method, the developed procedure affords the detection limits at a level of 0.01 mg/ml.

The possibility in principle for obtaining vitamin K₃ (2-methyl-1,4-naphthoquinone) by the diene synthesis reaction from such available substrates as 2-methylphenol (o-cresol) and 2-methyl aniline (o-toluidine) has been shown. Solutions of Mo-V phosphoric heteropoly acids represent bifunctional catalysts for these processes that make it possible to conduct oxidizing and diene synthesis reactions as a one-stage process.