Home – Home – Jornals – Chemistry for Sustainable Development 2012 number 2

Novel data are discussed concerning tritium content in surface, ground and underground waters in the area the accidental pacific underground nuclear explosion “Kraton-3” in August 24, 1978. Early studies on the object “Kraton-3” were mainly devoted to the determination of surface contamination in the taiga landscape at the moment of the explosion, and the further redistribution and migration of radionuclides from contaminated areas under the influence of exogenous and biogenic processes. For the first time, an issue was considered whether the underground source of radioactivity is opened. Basing on the analysis of radioecological and geochemical data, a conclusion is drawn that there occurs a significant delivery of radionuclides from the cavity of the explosion to the surface of the earth.

Using ferromagnetic resonance and electron microscopy, dispersing bulk nickel and its alloys in the course of interaction with the reaction medium (1,2-dichloroethane and hydrogen) accompanied by the intense growth of carbon nanofibres was studied. It is demonstrated that in all the cases the formation of rather uniform nickel nanoparticles occurs with the characteristic size of 200–300 nm. The efficiency of this method for studying the formation of nickel particles at the very initial stages of the reaction was demonstrated, including the induction period, when the use of electron microscopic studies is not efficient enough.

Deep methanol oxidation in aqueous solutions with the methanol concentration lower than 2.0 mass % within temperature range 250–450 °С is considered. Experiments were carried out with industrial catalysts based on aluminum oxide with active components such as platinum as well as copper, chromium, iron, and magnesium oxides. The minimum concentration of methanol after oxidation (≤3 mg/dm³) was achieved for CuO/Cr₂O₃/Al₂O₃ catalyst. Most likely, the methanol oxidation on the catalysts of this type proceeds according to the Mars–van Krevelen mechanism, wherein reactive oxygen species responsible for deep oxidation are presented by the lattice oxygen of the catalyst. TPD spectra were obtained for oxygen, methanol, water, as well as for methanol and water in simultaneous presence, within the temperature range of 100–950 °С.

Composition, surface structure (including those after annealing at high temperature) and the catalytic activity in the steam conversion of naphthalene were studied for Ce-, Zr- and Mn-containing oxide layers obtained on titanium by means of plasma electrolytic oxidation. The composition and structure of oxide systems were studied by means of XRD phase analysis, energy dispersion analysis and scanning electron microscopy. It was demonstrated that Ce-, Zr-containing structures exhibit a rather high thermal stability: the elemental and phase composition, the structure of their surface remain almost unchanged after annealing in atmospheric air at the temperature values up to 800 °С. The catalytic studies demonstrated a rather high activity of Ce-, Zr-containing coatings in the reaction of naphthalene steam conversion at the temperature values up to 850 °С. Mn-containing oxide structures have developed surface covered with nanowhiskers those were not detected after thermal treatment. Mn-containing oxide systems exhibited a lower level of naphthalene conversion as compared to Се-, Zr-containing coatings, which could be connected with substantial changing their surface and with the formation of low-active fused manganese silicates at high temperature values.

Results are presented concerning the determination of lead and mercury total content in oligotrophic peat bog deposits in West Siberia. It is demonstrated that the current level of atmospheric lead fall-out is insignificant, the lead concentration in the upper layers of peat deposits are far below the level of background values established for other territories. Data concerning the mercury concentrations are comparable with those obtained earlier for other background areas. The distribution of elements depending on the physical and chemical properties of peat was revealed. A selective absorption of heavy metals by the humic and fulvic acids of peat organic matter was found to occur.

A series of environmentally safe highly efficient bifunctional catalysts for hexane skeleton isomerisation was studied. It was demonstrated that the activity of the catalysts is determined mainly by acidic properties. Reaction rate values and selectivity level with respect to target products were determined depending on the concentration of Lewis acid, whereas the content of Brцnsted acidic centers was maintained approximately constant. The data obtained could serve as a basis for the development of Russian highly efficient catalysts for light gasoline skeleton isomerisation those could be used for obtaining branched isomers for С₅-С₈ hydrocarbons with the octane number ranging within 92–105.

A method was developed for obtaining granulated sulphur-containing sorbents with the use of wastes from epichlorohydrin production containing about 76 % of 1,2,3-trichloropropane was developed. The interaction between the wastes and sodium polysulphide is carried out in the presence of petroleum coke particles playing the role of polycondensation centres. The sorbents obtained are capable of extracting metals from aqueous solutions to exhibit the following sorption capacity (mg/g): Zn up to 74, Cd up to 31, Hg up to 152, Cu up to 25. The sorption mechanism is under discussion.

A composition was studied for polycyclic aromatic hydrocarbons formed in the course of the pyrolysis (160–650 °С) of the resin-asphaltene components of heavy crude oil from the Permian–Carboniferous age deposits of the Usinskoye field (Komi Republic). It was demonstrated that the molecules of resins and asphaltenes inherent in the oil contain the same set of aromatic fragments. Among them there were identified bi- and tricyclic fused aromatic hydrocarbons and (С₁-С₃ alkyl derivatives, tetra -, penta -, hexacyclic substances and phenyl-substituted compounds (diphenyl-, phenylnaphthalenes, terphenyls, phenylphenanthrenes). Tri- and tetracyclic aromatic hydrocarbons are prevailing, which hydrocarbons should form the basis for the composition of oil fractions produced by means of thermal processing the heavy hydrocarbon feedstock.

Influencing the parameters of the crystallization process and the preparation of raw materials upon the quality of manganese acetate tetrahydrate was investigated. Optimum parameters were determined for the process of crystallization. Results are presented concerning studies on the influence of leaching the manganese carbonate upon the process purifying from calcium and chlorine impurities. A low-waste technological scheme is proposed for the production of high purity manganese acetate tetrahydrate.

Regularities were studied concerning dimethyl disulphide transformation in an atmosphere of helium in the presence of solid catalysts those differ from each other in the acid-base properties. The catalysts containing mainly BrØnsted acidic centres or strong basic centres on the surface exhibit a low activity level. Under the action of weak Lewis acidic centres, the dimethyl sulphide is formed at a low rate, however with increasing the strength of these centres the rate of dimethyl sulphide formation increases. For a catalyst to exhibit a high activity level in the formation of dimethyl sulphide, it is required for the presence of strong Lewis and BrØnsted centers, as well as basic centres with a moderate strength on the surface. The results of kinetic studies indicate that before 200 °C there is a parallel reaction scheme realized, whereas at a higher temperature the reaction scheme is consecutive. The reaction kinetic type varies from the first-order kinetics to zero-order one depending on the concentration of the substrate. The rate of dimethyl sulphide formation increases with increasing the temperature, the apparent activation energy amounts to (55±1) kJ/mol. The selectivity level of dimethyl sulphide formation in the case of complete conversion level of the substrate reaches 50–60 %.

Using the methods of XRD phase analysis, Raman and IR spectroscopy, thermogravimetry and chemical analysis the process of bismuth (III) citrate precipitation was investigated concerning the solutions of perchloric acid, nitric acid and hydrochloric acid under adding thereto a solution of citric acid or trisodium citrate. Conditions were determined with respect to the formation of compounds BiC₆H₅O₇, BiОC₆H₇O₇ · H₂O and Bi₆(OH)₆(C₆H₅O₇)₄ · 6H₂O. It was demonstrated that bismuth (III) citrate such as BiC₆H₅O₇ used in medicine for the synthesis of pharmaceuticals and in microbiology the production of bacterial preparations are appropriate to obtain via the precipitation from nitric acid solutions from manufacturing bismuth compounds with adding citric acid; the molar ratio between citrate ions and bismuth ions in the solution should be equal to 1.1–1.2, the process temperature being of (60±5) °С.

The bottom ash and fly ash investigated in this study originated from the bubbling fluidized bed boiler at the large-sized (246 MW) combustion plant of a pulp and paper mill complex. Approximately 40 % of the energy produced by the boiler originated from the incineration of commercial peat fuel, and approximately 60 % from the incineration of clean forest residues (i.e. bark, woodchip and sawdust). Due to the low heavy metal concentrations (As, Cd, Cr, Cu, Hg, Pb, Ni and Zn) in the bottom ash and fly ash, these residues are potential forest fertilizers as such. However, additional Ca is needed for the bottom ash, because its Ca concentration of 5.8 % (d.w.) was lower than the statutory Finnish minimum limit value of 6.0 % (d.w.) for Ca in forest fertilizers. Except for potassium, nutrients and heavy metals were enriched in the fly ash. Compared to the total phosphorous content, which was 0.2 % (d.w.) in the bottom ash and 1.3 % (d.w.) in the fly ash, the water soluble phosphorous content in both ashes was negligible (<0.01 %; d.w.). This finding is discussed on the basis of the minerals observed in the XRD data for the ashes, as well as on the grounds of findings reported by other researchers.

For the first time a pK spectroscopy technique was applied to study the influence of Lewis acids upon changing the acid-base properties of cellulose suspensions. Basing on the cellulose pK spectra obtained before and after the modification in the solution of titanium tetrachloride, it was demonstrated that the action of titanium tetrachloride on the cellulose results in weakening the bonds between hydrogen ions and appropriate acid-base groups, thereby the number of these groups remain unchanged. The powdered cellulose obtained under the influence of titanium tetrachloride differs from the original (fibrous) one in a high ion exchange capacity.

A series of sulphides belonging to pinane family was obtained basing on (1<i>S</i>)-(–)-β-pinene and its oxide. The asymmetric oxidation of β-hydroxysulphide with the fragment of 2-mercaptoethanol using an oxidizing system such as Ti(O-<i>i</i>-Pr)₄/R-C₆H₅CH(OH)COOH/<i>t</i>-BuOOH resulted in obtaining diastereomerically pure hydroxysulphoxide with pinane structure.

The stability of green tea catechins was studied in the solid phase and in aqueous solution in the course of storage, degradation rate values were determined depending on ambient conditions. The stability of catechins was investigated in the course of mechanical activation; possibility is demonstrated for obtaining a mechanocomposite consisting of plant raw material and ascorbic acid, with a higher stability.

Chelate complexes of selenium and iodine ions with the peptides of elastin protein were obtained. The parameters of sorption of selenium- and iodine-containing chelate complexes of elastin on natural zeolite tuff depending on the concentration of chelate complex and the time of contact between the chelate complex and tuff were studied.