Home – Home – Jornals – Chemistry for Sustainable Development 2009 number 3

Review of publications on chemistry, properties and outlooks for the application of the boron and nitrogen containing heterocyclic compound borazine (borazol), or cyclo-Н₃В₃N₃H₃, and some its derivatives, as well as the starting compounds for its synthesis is presented, embracing the period since 1926 (the date of borazine discovery) till present. It is shown that the information reported in classical works is essentially urgent even at present. Borazines were used to develop promising methods of obtaining insulating layers and films based on boron nitride h-BN and carbonitrides by means of the thermal or plasmachemical vapour decomposition, as well as coatings composed of condensed heterocycles of borazine derivatives. The data obtained by the authors of the review concerning solid-phase Mechanochemical methods of synthesis of borazine and its derivatives - N-trimethylborazine and N-triethylborazine are reported. The advantages and the possibility of technical implementation of these methods in comparison with other known methods are specified.

Interaction of oxohydroxobismuth (III) nitrate trihydrate of the composition [Bi₆O₅(OH)₃](NO₃)₅ ⋅ 3H₂O with aqueous solutions of citric acid was studied by means of X-ray phase analysis, thermogravimetry, IR spectroscopy and chemical analysis. The effect of the concentration of citrate ions, pH of the medium and process temperature on the rate of exchange of nitrate ions for citrate ions was investigated. The conditions of the formation of bismuth citrate of he composition BiC₆H₅O₇ were determined. The reasonableness of the synthesis of high-purity bismuth citrate by the interaction of oxohydroxobismuth (III) nitrate trihydrate with the solution of citric acid was demonstrated.

Results of chemical and low-temperature thermal regeneration with air and nitrogen of industrial active coal of grades AG-OV-1 and SKD-515 worked out in pyridine adsorption from model solutions and real waste waters are presented. It is shown that the use of chemical regeneration is unreasonable. The data of thermogravimetric analysis were used to choose an optimal temperature for the regeneration of active coal in the flow of nitrogen and in the air. A comparative analysis of the efficiency of low-temperature thermal regeneration in inert and oxidative environment was carried out. The results allows us to recommend low-temperature thermal regeneration with inert gas (nitrogen) for practical purposes.

It is established that the coefficient of biological absorption of rare earth elements allows one to characterize them by the weak level of intake by the top mass of pastoral grass. The concentrations of lanthanum, neodymium and samarium in the top phytomass of a natural pasture of the cryolite zone in Transbaikalia is 2.3-4.5 times lower than in roots.

It is established that after leaching calcium by ammonium chloride into solution from the product of thermal decomposition of phosphochalk (technical-grade calcium carbonate) obtained by conversion of phosphogypsum with soda solutions, the insoluble residue is a concentrate of strontium and rare-earth elements (REE); the concentrations of strontium and REE reach 9-10 and 4.5-5.1 %, respectively. The extraction of REE into solution with the help of different acids is considered. It is shown that the degree of leaching the REE into solution reaches 96-97 % in the presence of reducing agents. The leaching solutions contain 4.2-4.6 g/dm³ REE and can be processed to obtain REE compounds. The insoluble residue after REE leaching is a strontium concentrate with strontium sulphate content of 54.5-62.9 %.

Results of the investigations of the properties of humic preparations obtained by means of the colloid chemical separation of the salts of humic acids are presented. Substantial differences between the properties of humic preparations isolated in acidic and alkaline media are demonstrated, first of all in changes of the elemental composition of humic preparations, as well as the composition and ratios of functional groups in the molecular structure of these compounds. Results of the determination of sorption activity of the obtained humic preparations for ion sorption from monoionic or binary solutions are reported. The revealed regularities are considered as a basis of the development of a number of new sorption and land-improving materials for nature conservation purposes.

Interaction of artificial geochemical barriers with nickel sulpahte solution was investigated using chemical analysis, X-ray phase analysis, scanning electron microscopy and thermodynamic modeling. It was shown that the combinations of active silica with carbonatite, as well as serpophite with carbonatite, are promising materials for making artificial geochemical barriers.

Composition and sorption properties with respect to heavy metal ions are investigated for chitin-glucan complexes (CGC) isolated from the mycothallus of the fungi of Russula genus collected in teh zones with different levels of anthropogenic pollution. The amount of isolated insoluble CGC does not exceed 1.1 %, chitin content (Ch) is not more than 0.65 %. Passing from a non-polluted zone to polluted ones, an increase in the content of CGC and Ch in all the three kinds of the biomass of mycothallus is observed. The sorption capacity of CGC with respect to the ions of lead (II) and copper (II) is not high: it reaches 107 and 123 μmol/g, respectively, but the high selectivity (100 %) of copper (II) ion sorption is exhibited. For the investigated CGC, a trend to increased sorption capacity of CGC with an increase in the biotope pollution with heavy metals is observed. These investigations may be applied in using widespread fungi with the limited food and taste value of the Russula genus - russules - for obtaining sorption materials.

Methyl ester of 2-cyano-3,12-dioxo-11-deoxo-18-βН-glycyrrhet-1(2),11(9)-diene acid was synthesized by means of the combined modification of А and C rings of the 18-βН-glycyrrhetic acid.

Precipitation of bismuth salicylate from its nitrate solutions and the interaction of trihydroxo-pentaocohexabismuth (III) pentanitrate trihydrate [Bi₆O₅(OH)₃](NO₃)₅ ⋅ 3H₂O with the solutions of sodium salicylate and salicylic acid was studied by means of X-ray phase analysis, IR and Raman spectroscopy, thermogravimetry and chemical analysis. The dependence of the rate of nitrate ion exchange for salicylate ions on temperature and pH of the medium was investigated. The conditions of the formation of bismuth (III) oxide-salicylate of he composition Bi(C₇H₅O₃)О were determined for precipitation from nitrate solutions and for the solid-to-solution reaction. It is shown that it is reasonable to synthesize these preparations of high purity for use as a drug substance in antiulcer and antidiarrheic preparations by means of the interaction of [Bi₆O₅(OH)₃](NO₃)₅ ⋅ 3H₂O with the solution of salicylic acid.

Eco-friendly method for nitration of aromatic compounds using different solid supports has been successfully reported.

Results of the investigation of bone tissues with the help of XPA, IR spectroscopy, thermal analysis, mass spectrometry are reported. It is shown that the crystal basis of the bone tissue is poorly crystallized nonstoichiometric apatite. It is established for coxarthrosis that the amount of PO₄^3- decreases, while the content of CO₃^2- and the organic component increases, therefore, the degree of crystallinity and the stoichioemtry of bone apatite decrease. The differences between pathogenic and reference samples in the concentrations of manganese, tin, iron, copper and chromium were revealed.