Home – Home – Jornals – Chemistry for Sustainable Development 2005 number 1

The data on natural sources of betulin and methods of its extraction are systematized in the review. Transformations of betulin and its available derivatives are considered. The data on the biological activity of betulin, its natural and synthetic analogs are presented. The promising character of the compounds based on betulin for creation of antiviral and antitumour agents.

The concentrations of chlorinated phenols (CP) have been determined in superficial water of Selenga River and its basic tributaries, which provide for 53 % of the Baikal Lake drainage. It has been found that a level of contamination of the Selenga River basin by CP is relatively low and the total CP content comprises 0.36-1.85 mg/l. The presence of CP in natural water is caused mostly by the local anthropogenic and natural sources, for identification of which the use of the ratios of net concentrations of 2,4,5- and 2,4,6-trichlorophenols and 2,4- and 2,6-dichlorophenols, together with 2,4,5- and 2,4,6-trichlorophenols and 2-chlorophenol is suggested.

The part played by highly dispersed particles of metals of iron subgroup in catalytic decomposition of hydrocarbons through the carbide cycle mechanism has been considered. A crucial correlation between their crystallographic characteristics and the structure of formed graphite composites has been shown. The major factors have been determined that enable controlling the processes of formation of graphite filaments and fibres.

The process of deep phenol oxidation in electrochemically activated medium has been studied in an effort to develop the process for neutralizing the wastes of highly toxic matter. The known scheme of phenol destruction to carbon dioxide and water through the stage of p-benzoquinone and carboxylic acid formation has been confirmed. The comparative analysis of specific reaction rates of phenol oxidation has been conducted using the various oxidizers including oxygen, hydrogen peroxide in the presence of Fe²⁺, and ozone and also by means of electrochemical oxidation.

The possibility in principle for applying the concentrated aqueous solutions of heteropoly acid of composition H₅PV₂Mo₁₀O₄₀ (HPA-2) as the stable reversibly reacting oxidizers was shown. The reduced form of HPA-2 can be oxidized by oxygen at 353-433 K under a pressure of as much as 8 kg/cm² thereby reclaiming HPA-2. An effect of temperature and pressure on the depth and reaction rate of oxidation has been investigated. Reduced and oxidized HPA-2 solutions are stable up to 463 K.

An elemental analysis of superficial layers of the particles of atmospheric aerosols (AA) in Novosibirsk Region and the Baikal region has been performed with the technique of Secondary Ion Mass Spectrometry. It has been found that superficial layers (one-two) of monolayer of all aerosols are covered by adsorbed hydrocarbons, nitrogen-bearing compounds, by other more complex compounds, and water. It has been demonstrated that an erosion of aluminosilicate soils with admixtures of iron, titanium, alkaline and alkali-earth metals provides the basic source for AA formation. Action of water results in Na and Ca "washing out" from superficial layers and formation of hydroaluminosilicates. By means of X-Ray Absorption Near Edge Structure technique, the phase and charge state of iron in AA samples taken in Irkutsk have been determined. With the aim of analysing the composition of gases adsorbed on the surface, an attempt has been made to apply a technique of temperature-programmed desorption.

New efficient microfertilizers based on neodymium and natural zeolites are proposed. The equilibrium and kinetics of sorption of neodymium ions from the solutions of nitrate and sulphate by mordenite-containing tufa are investigated. It is established that neodymium is fully extracted from diluted solutions (<0.002 M); with an increase in concentration, sorption capacity of tufa with respect to neodymium ions is observed to decrease sharply. The kinetic parameters of sorption process are determined.

An effect of the accelerated electrons generated by the electron accelerator on the composition and indexes of the permolecular structure of brown and mineral coals of a metamorphism series has been studied. It has been demonstrated that the effects of ionizing action are controlled to an essential degree by the irradiation conditions and by the stage of coal metamorphism. Middle rank and high rank mineral coals show stability when exposed to an electron beam: their composition, swelling capacity, and the yield of solubles vary a little upon an irradiation with doses up to 200 Mrad. This may be related to the fact that the derivatives of polycondensed aromatic compounds that make up the mentioned coals may cause the radical and ion-radical reactions to decay inside the organic bulk due to the large electron affinity of these derivatives and trapping the low-velocity electrons. Low-rank coals (brown and mineral) with a great deal of aliphatic chains are rather easily subject to the radiation chemical transformations. When absorbing the small dozes (10-50 Mrad), the destruction processes including partial breaking of the valence cross-linking between macromolecules become dominant which leads to loosening the permolecular structure and to an increased capability of interaction with the molecules of organic solvents. The large radiation dozes (more than 50-100 Mrad) promote preferentially the cross-linking processes and structural regularity.

The photochemical stability of aqueous solutions of humic acids (HA) extracted from black soil and from solonetz soil from different depth R is studied by means of luminescence for the first time. It is shown that the photochemical activity of both HA samples extracted from the sub-surface soil layers is higher. The method of photochemical probing is concluded to have advantages over other methods for discrimination of the sorts of HA molecules.

Possible soil pollution, as a consequence of dusting of the tailings of copper and nickel ore dressing withdrawn from operation, is modeled. The results show that sulphide-containing final tailing products brought into soil cause rather intensive transformation of heavy metals into water-soluble forms. Thus formed organomineral complexes are stable and yield to no purification with the help of conventional reagents.

The seasonal dynamics of heavy metals (Fe, Mn, Zn, Cu, Cr, Ni, Co, Cd, Pb) in water, bottom sediments is shown; their concentrations in the higher aquatic plants (Elodea canadensis) and in zoobenthos (mollusca bivalvia) from the Cherkalov Sor bay of Lake Baikal are analyzed. It was established that the maximum permissible concentrations for fishery water bodies are exceeded for Fe, Mn, Zn, Cu in water all year long, for Pb during spring tide. The concentrations of all these metals in bottom sediments in fractions <60 mm exceeds the background values by 20-50 %, accumulation of Cd is almost 3 times higher. It is shown that redistribution of Mn, Zn, Cu, Cd is substantially affected by aquatic plants and molluscs.

For carbonization of binary compositions of pine sawdust with a number of gumlike products of coal processing as an example, it is shown that the use of compositions involving compounds of different nature as the initials for obtaining carbon sorbents allows one to change the mechanism of thermal destruction shifting the temperature ranges and decreasing the rates of intensive decomposition. The yield of carbon residue increases non-additively. Such an approach allows one to broaden the assortment of carbon sorbents, including the materials which cannot be carbonized in the individual form.

Oxidation and modification processes in the carbon composite material of "Tekhnosorb" grade are investigated. Carbon materials, oxidized and modified with the compounds of antimony (V) (NUMS-O, NUMS-Sb), are examined by means of thermal analysis, X-ray diffraction. It is established that antimonic acid can be synthesized on the surface of HUMS-O either in the crystal form and in the amorphous one, depending on the temperature of oxidation of the carbon surface.

For the first time, β-asparagine was isolated from burdock roots and identified. It was established that β-asparagine extracted from roots exhibits cytostatic and apoptosis-inducing activity. Synthetic L-asparagine (manufactured in Japan) exhibits neither cytostatic nor apoptosis-inducing activity.