Home – Home – Jornals – Chemistry for Sustainable Development 2011 number 3

Nanosized powders of the oxides SnO₂ and CoFe₂O₄ with the specific surface of 130 and 160 m²/g, respectively, were obtained by means of mechanochemical synthesis from the salt systems of the corresponding reagents. The physicochemical characteristics of the powders and their absorption ability with respect to microorganisms and organic pollutants were studied. It was established that the sorption of bacterial cells Microccocus albus and Pseudomonas putida during filtration of the microbial oil-polluted suspension through the columns filled with the nanosorbents under investigation is 99.999-100 %. Due to the developed specific surface, the nanosorbents can be used for high-quality purification of drinking water from microorganisms and organic pollutants, which is important in the effors to decrease the infectious morbidity of the population.

A detailed physicochemical characterization of columbite and tantalite samples from different locations in Nigeria has been undertaken. Parameters such as moisture content, loss of mass on ignition, pH, and the specific gravity of columbite and tantalite samples from different locations were determined and compared. The results showed that the moisture content of columbite samples obtained from Kwara and Plateau States are 1.0 and 0.53 %, respectively, while the percentage of moisture content of tantalite samples obtained from Kwara, Kogi, Kaduna, and Nasarawa States are 0.37, 0.30, 0.67 and 1.00 %, respectively. The percentage loss of mass on ignition of columbite samples obtained from Kwara and Plateau States and tantalite samples from Kwara, Kogi, Kaduna, and Nasarawa States are 6.1, 3.6, 7.7, 2.4, 4.4 and 4.3 %, respectively. Values of 2.40, 3.76, 3.65, 3.37, 2.07 and 1.96 were obtained as the specific gravities of columbite samples obtained from Kwara and Plateau States and tantalite samples from Kwara, Kogi, Kaduna, and Nasarawa States, respectively, and finally, the mean pH for each of columbite and tantalite samples was approximately 7.6.

Synthesis of the nanopowders of СеО₂ and ZnO was carried out from the solutions of cerium (III) and zinc salts in the presence of hexamethylenetetramine. The effect of the major synthesis parameters inclding the molar ratio of the reagents and synthesis temperature on the micro-morphology of the formed oxide powders was established. The possibility to vary the size of ZnO and CeO₂ nanoparticles under the hydrothermal microwave conditions was demonstrated.

Content of conventionally essential microelements (Li, B, Si, Ti, V, Ni) was studied in 21 species of medicinal herbs growing on different kinds of soil in Western Transbaikalia under the ecological phytocoenotic conditions of arid steppe, meadow with insufficient and normal wetting, and meadow bog. The species and ecological specificity of microelement accumulation in plants was determined. Different levels of microelement content in medicinal herbs and the concentrating plant species for Li, B, Si, Ti, V, Ni were established. According to the results of investigation, boron is attributed to the elements with intense absorption from soil, lithium to medium, nickel to weak, vanadium and titanium to the elements of very weak absorption.

Composite material based on nanofibrous aluminium oxyhydroxide activated with metal nanoparticles (Ag, Co, Fe, Cu) was developed. Its catalytic properties in the oxidation of isopropylbenzene were studied. It was demonstrated that aluminium oxyhydroxide can be used as a support for composite materials. Isopropylbenzene oxidation in the presence of activated aluminium oxyhydroxide proceeds selectively, predominantly with the formation of isopropylbenzene hydroperoxide.

Effect of the parameters of crystallization process and the preparation of the initial raw material on the quality of manganese nitrate hexahydrate was investigated. The optimal parameters of crystallization process were revealed. Results of the investigation of the effect of metal manganese leaching on the purification from admixtures of calcium and chloride ions are presented. A low-waste technology of the production of high-purity manganese nitrate hexahydrate is proposed.

Interaction of the artificial geochemical barrier (a combination of serpentine and carbonatite) with the solution of copper sulphate was studied. Chemical, X-ray, derivatographic analyses and thermodynamic modelling were used. It was demonstrated that the products of the interaction of the barrier with copper sulphate solution are basic copper sulphates – brochantite and poznyakite, as well as chlorite-like phases.

Results of the field studies, chemical analytical and numerical investigation of the pollution of the snow cover in the zone affected by the sources in Barnaul emitting polycyclic aromatic hydrocarbons (PAHs) are reported. By means of gas chromatography/ mass spectrometry, 19 individual PAH were determined in the collected snow samples. Numerical analysis of the experimental data was performed, and the quantitative regularities of the regional emission of PAHs from the territory of Barnaul were found. By means of the correlation analysis, a linear dependence was established between average logarithms of PAHs concentrations measured in the vicinity of stationary meteorological posts at the territory of the city and beyond its bounds at the direction of prevailing drift. The possibility to construct an economic system of monitoring for estimation of the urban atmospheric pollution for a long-term period was demonstrated.

Effect of the surface density of the emitter on the results of X-ray fluorescence analysis of diary products was studied theoretically and experimentally with the spectrometer having the geometry of total external reflectance (XRD TER). The models of the dependence of the error of milk sample preparation on the level of milk dilution with water and on the volume of aliquot deposited on the substrate were obtained with the help of mathematical planning of experiments. The physical interpretation of these models is taken into account. The models of the dependence of the detection limit of elements in milk on the above-indicated factors were obtained. A procedure of non-destructive determination of P, S, Cl, K, Ca, Fe, Ni, Cu, Zn, Br, Rb, Sr, Pb in milk; and in diary products with the help of XRD TER was developed. Metrological investigation of the developed procedure was carried out.

For water reservoirs of the system of Belovo settling tank (Kemerovo Region, Russia) as example, the species composition, structure and abundance of phyto- and zooplankton of the technogenic water reservoir formed by acidic ore drainage water are characterized. According to the chemical composition, the water of these water bodies may be related to a special technogenic type never occurring under natural conditions. The species diversity and composition of the plankton depict the features of the chemical composition of water and allow us to consider these water objects as extremal localities.

Analysis of average monthly, maximal and minimal values of the mass concentration of aerosol in Novosibirsk and at its south-east outskirts during the years 2005–2008 was carried out. It was revealed that the levels of atmospheric air pollution with aerosol in the city and in the suburbs are formed non-equivalently. A trend for a more stable character of air pollution in the city is observed along with the higher variability in the suburbs.

Strategy to involve eco friendly phase transfer catalysis (PTC) with nucleophilic displacements has always been of great interest to study. Therefore, comparative studies of chlorination, azidolysis and indirect amination for synthesis of novel 7,9-disubstituted 5-methyl-7H-tetrazolo[1,5-c]pyrrolo[3,2-e]pyrimidines 4 and their ring cleavage to 5,7-disubstituted 2-methyl-4-amino-7H-pyrrolo[2,3-d]pyrimidines 5 have been undertaken with and without PTC. Chlorination of 5,7-disubstituted 2-methyl-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-ones 2 obtained from 1,4-disubstituted 2-amino-3-pyanopyrroles 1, followed by azidolysis of 5,7-disubstituted 2-methyl-4-chloro-7H-pyrrolo[2,3-d]pyrimidines 3 forming 4 and their chemoselective tetrazole ring cleavage to 5 have been carried out with and without PTC. PTC assisted one pot synthesis of 5 directly from 3 have also been reported.

Thermolysis of the samples of pyrobitumen of petroleum from the Usinsk deposit was carried out at a temperature of 160, 200, 250, 300, 450 and 650 °С. Pyrobitumen samples after thermolysis were analyzed by means of IR spectrometry, the elemental composition of the samples was determined, as well as the molecular masses and the structural group characteristics, and the hypothetic structures of average molecules were constructed. Liquid and gaseous products formed as a result of pyrobitumen thermolysis were analyzed by means of GLC and GLC/GAC. On the basis of the data on the thermal stability of saturated aliphatic and cyclic sulphureous fragments and change in the total sulphur content in thermolyzed pyrobitumen, we calculated the amounts of alkyl and thiacyclane sulphur incorporated into the molecules of pyrobitumen.

Full conductivity, diffusion and oxygen exchange properties in the composites (100 - х)La_0.8Sr_0.2Fe_0.7Ni_0.3O_{3 -δ}/xCe_0.9Gd_0.1O_1.95 (LSFN/CGO, x - volume fraction, 0 < x < 71.1 %) were studied by means of the relaxation of electrical conduction at 700 °C for partial oxygen pressure within the range (0.2–3) · 10^-3 atm. It was demonstrated that the electric conduction of the composites decreases monotonously with an increase in the concentration of CGO, while the coefficient of the chemical diffusion of oxygen (D_chem ) increases. The constant of oxygen exchange (k_chem ) is higher for composites than for individual phases LSFN and CGO. The dependence of k_chem value on the composition of the composite may be due to the effect of interphase boundaries on oxygen exchange processes. The total efficiency of oxygen transport in LSFN/CGO composites at a temperature of 700 °C is maximal for the composites with the volume fraction of CGO close to 70 %.

The possibility of preliminary reduction of U₃O₈ with hydrogen and ammonia before its fluorination for the purpose of increasing uranium (IV) content in the product is considered. Results of the investigation aimed at the determinaiton of optimal temperatures and the kinetics of U₃O₈ reduction under non-isothermic conditions by means of temperature-programmed reduction are presented.