Home – Home – Jornals – Chemistry for Sustainable Development 2011 number 1

Sorption of platinum chloro complexes from solutions with the help of oxidized carbon sorbents was studied. An effect of the oxygenated surface functional groups of oxidized carbon sorbents on their sorption capacity was studied using IR spectroscopy, pH-metry, titrimetry. Sorption isotherms for H₂PtCl₆ and Н₂PtCl₄ were obtained. It was established that the capacity of the sorbent with respect to H₂PtCl₆ increased by a factor of 2.4.

UDC 544.723: 546.26: 546.92

It was established that the catalysts based on vanadium and molybdenum oxides exhibit activity in the generation of the singlet form of molecular oxygen. The major reaction on mixed oxides having the composition xV₂O₅ · yMoO₃ is not the one-electron oxidation but the addition to the double bond, preferably in the meta position. It was demonstrated that the oxidation of toluene on individual vanadium and molybdenum oxides follows independent routes: on V₂O₅, oxidation is realized mainly at the benzene ring, while on MoO₃ it occurs at the side chain.

Flavonoid content was studied in the organs of the top part of plants of seven species of Hedysarum L. genus (H. alpinum L., H. flavescens Regel et Schmalh., H. austrosibiricum B. Fedtsch H. neglectum Ledeb., H. theinum Krasnob., H. gmelinii Ledeb. и H. tschuense A. I. Pjak et A. L. Ebel) growing in the forest-steppe zone of West Siberia (Novosibirsk) and in natural populations in the Republic of Altay and Northern Kazakhstan. The species peculiarity of the accumulation of flavonoids was observed: the largest amount of flavonoids was detected in the leaves of H. flavescens, H. alpinum and H. theinum species (up to 15.0, 13.2 and 11.1 %, respectively). In general, all the studied species of Gamotion section are distinguished by exclusively high flavonoid content independently of age. The representatives of Multicaulia section H. gmelinii and H. tschuense are distinguished by somewhat lower (in comparison with the above-indicated species) flavonoid content (2.6 and 1.8 %, respectively). The species of Gamotion section are to be recommended as the source of flavonoids because the introduced and wild plants are characterized by the exclusive ability to synthesize the large amount of these compounds.

Triterpenoids with a chlorovinyl fragment were synthesized through the interaction of diacetoxy-29-nor-20-oxobetulin and 2-cyano-3,4-seco-23-nor-4,28-dioxo-19β,28-epoxyoleane with phosphorus pentoxide via boiling in chloroform.

By introducing α-Al₂O₃ powder with particle size 25 nm, in the amount of 1–10 mass %, into the solution of aluminium nitrate or into dry aluminium hydroxide, the kinetics of the formation of the stable α-phase during subsequent heating of the precursor gets accelerated substantially. Depending on the amount and method of introducing the seeding agent, the complete transformation of the precursor into α-Al₂O₃ occurs at a temperature within the range 800 to 930 °С. The powder formed at such a low temperature is composed of porous aggregates 10–20 mm in size; the size of crystallites comprising the aggregates is independent of the amount of seeding agent introduced and is equal to approximately 50–60 nm. Grinding under soft conditions leads to the destruction of aggregates and to the formation of nanopowder which is active towards caking. Later on, a ceramic material with the porosity at a level of 1 % is obtained from the powder at 1450 °С.

Deactivation and processing of the man-caused wastes of molybdenum from the production of uranium dioxide by means of fluorination with elemental fluorine were studied. The level and depth of molybdenum contamination with radioactive substances were established, the major physicochemical parameters of molybdenum fluorination were determined: the equilibrium composition, duration and conditions of reaction. The apparent activation energies were determined, and kinetic equations were deduced.

A study was carried out between mid June-August, 2010 to estimate the level of organic pollution of the Odo Oba River in Osun and Oyo States. The parameters used to monitor the degree of pollution were Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD₅), Chemical Oxygen Demand (COD) and Permanganate Value (PV). 14 samples were collected along the water link, 200 m away from each other from the source to where the river discharges into the Asejire River. The values of DO, BOD₅, COD and PV ranged between 1.01-5.38, 04.2-24.2, 103-337 and 12-96 mg/L, respectively. The mean and standard deviation values were also (3.18±1.86), (15.35±6.59), (179±85) and (57.7±32.4) mg/L, respectively. The value of COD recorded from the analysis is greater than that of BOD₅. This suggests that the river contains a high proportion of biologically non-degradable and inert matter as a constituent of gross organic pollution. From the results of the analysis, the Odo Oba River is heavily polluted. The result of the analysis places the Odo Oba River water quality in class V of the Classical Prati Water Quality Index Scale.

Evaluation of the quality of atmopsheric air in Novosibrsk was made on the basis of the examination of solid suspended particles (SSP) measured by the Rosgidromet system and by the Institute of Chemical Kinetics and Combustion SB RAS. It was established that the fraction of particles ≤10 μm (SP₁₀) in SSP is equal to 0.67. Evaluation of the quality of atmospheric air on the basis of SP₁₀ did not reveal other pollutants in the urban air as established by Rosgidromet according to the existing procedure.

Cross-linked copolymers were obtained by modifying polyvinylglycidylic ether of ethylene glycol with ammonia and ethylenediamine. The sorption capacity of these copolymers and the coefficients of metal distribution for of Hg(NO₃)₂ and UO₂Cl₂ aqueous solutions were determined.

Composition of gas mixtures formed during the electrochemical (in the presence of H₂O₂) oxidation of the wastes of human vital activities and subsequent decomposition of carbamide remaining in solution after the oxidation of metabolites was studied. A principal possibility of the selective catalytic oxidation of ammonia evolved due to the decomposition of carbamide to form nitrogen oxides was demonstrated, for the purpose of obtaining the salts of nitric acid those are well assimilated by plants.

Results are presented concerning studying the use of modified kraft lignin (sulphate) as a depressor reagent for non-metallic minerals in the flotation of disseminated copper-nickel ores. It was found that the modification of lignin according the Mannich reaction (aminomethylation) is a convenient method to implement and technologically sound recycling of the high-tonnage waste of pulp and paper industry.

Changes of the reactivity of mechanically activated coal from different stages of metamorphism in the processes of thermooxidative destruction were studied by means of thermal analysis. Thermogravimetric curves recorded at different heating rates were processed using the Model Free computer software. It was demonstrated that the intense mechanical treatment of coal at different stages of metamorphism long-flame and lean) causes an increase in the reactivity of coal, which is exhibited as a decrease in the activation energy over the whole temperature range of thermooxidative destruction. It was established that the most reactive coal towards combustion in the air environment among the studied kinds is mechanically activated low-metamorphosed long-flame coal.

Gastrointestinal extraction of essential microelements from biocomplexes based on the fronds of lichens and medicinal plants, prepared by solid-phase mechanical treatment, was studied. It was established that mechanical activation of these biocomplexes in the presence of sodium bicarbonate leads to the increased extraction of essential microelements in model environments.

Results of the application of X-ray diffraction studies, IR spectroscopy, thermogravimetry, spectrophotometry to the in vitro investigation of the phase composition of urinary calculi and the use of X-ray spectral microanalysis for the determination of their elemental composition are presented. The methods of X-ray diffraction and thermogravimetry were optimized for the quantitative determination of crystallization water in oxalates, and Lawry method was optimized for the quantitative determination of protein in all the kinds of urinary calculi. An interconnection between the hardness of oxalates, urates and phosphates, protein content and the kinds of microstructure was revealed.

A modified technique was proposed for the liquid-phase synthesis of hydroxyapatite allowing one to increase the stoichiometry of the product (the ratio Ca/P = 1.64) in comparison with the standard technique (Ca/P = 1.31). A comparison of the basic physicochemical characteristics for the synthetic and biological hydroxyapatite on the surface of zirconium was carried out. Calcium phosphate biocompatible coatings were obtained on the surface of zirconium basing on the synthesized and biological hydroxyapatite.

A mathematical model is presented for the calculation of optimal temperature values for the desublimation of metal fluorides and the number of desublimation steps those allow achieving the level of target product extraction from the vapour and gas mixture to almost 100 %. Results of modelling desublimation of uranium hexafluoride are presented.

Method of obtaining a sorbent based on bentonite clay and saw dust was studied. Different kinds of saw dust modification were considered, the kinetics and statics of the sorption of copper ions from aqueous solutions on the indicated materials were investigated. The mechanical characteristics were determined and the choice was mode for the composition of the material which is optimal for the purification of waste water from the ions of heavy metals.

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.

The method of self-propagating high temperature synthesis was used for preparing highly efficient catalysts from Ni-Al alloys corresponding to the basic composition of Ni₃Al intended for the process of carbon dioxide methane conversion. A low-dose modifying of platinum was carried out using ion implantation. Catalysts were tested in the course of carbon dioxide methane conversion at an atmospheric pressure and within the temperature range of 600-900 °С. It is demonstrated that the microstructure of the samples exerts a significant effect on the catalytic activity and stability of their functioning. A maximum activity is inherent in nanostructured catalysts those represent Pt clusters with size ranging from 0.3-0.5 to 3-5 nm, stabilized within the structure of intermetallic compound Ni₃Al and Al₂O₃. Using the methods of XRD, SEM, EDS, HRTEM, XPS, DSC-TG it was demonstrated that unmodified catalysts undergo a partial coking in the course of methane conversion into synthesis gas, whereas samples modified with platinum are stable and almost non-affected by deactivation due to carbonization.

A process of modifying the pore structure of mesoporous carbon carrier Sibunit obtained on the basis of technical carbon (soot) via introducing furfuryl alcohol into carbon at the stage of granulation was studied. An effect of modification conditions on the textural characteristics of the modified Sibunit was estimated. It was demonstrated that the introduction of furfuryl alcohol into technical carbon at the stage of granulation allows additional developing the Sibunit micropore volume up to 0.17-0.26 cm³/g. It was found that the percentage of micropores depends strongly on the degree of carbonization, i. e., on the amount of pyrocarbon deposited. When the carbonization level is higher than 60 %, the effect of the modification becomes negligible, which does not allow generating micropores in a great amount within the material. Basing on these results, a model was developed concerning the structure of modified Sibunit.

The procedure of the synthesis of aerogels Al₂O₃ and VO_x/MgO with the particle size of several nanometres was developed. The specific surface of materials obtained after drying under supercritical conditions exceeded 1000 m²/g. The possibility to govern the properties of aerogels through modification with acids and β-diketones of the solutions of alkoxides used as initial substances was revealed. The high activity of modified aerogel of Al₂O₃ in the processes of destructive sorption and catalytic dehydrohalogenation was demonstrated. It was shown that the aerogel VO_x/MgO exhibits high activity in the reaction of decomposition of Freon CF₂Cl₂.

By the example of the formation of Pt/Al₂O₃ catalytic system an influence was demonstrated exerted by the sequence of metal complex precursor transformations at the initial stages of catalyst preparation upon the state of platinum on the active surface of the finished catalyst. Views are expounded concerning the nature of the chemical bond between the metal complex and the carrier. Approaches are considered with respect to the quantitative differentiation of ion-exchange (outer-sphere), and coordinationally bonded (inner-sphere) adsorbed metal complex species, with respect to determining their chemical composition, as well as with respect to obtaining catalysts from a deposited precursor homogeneous in the type of interaction with the carrier.

Using the methods of Auger electron spectroscopy and the transmission electron microscopy, the process of aluminium activation by liquid metal alloy Ga-In was investigated. It was demonstrated that the components of the Ga-In alloy penetrate across the "biographical" aluminium oxide film to spread over the surface of aluminium metal. The activated aluminium interaction with tert-butyl chloride in liquid isobutene was investigated. It was revealed that the interaction takes place in three stages: the formation of aluminium chloride ionic complexes and aluminium chloride, the decomposition of tert-butyl chloride in situ obtained aluminium chloride systems, the formation of stable molecular aluminium chloride complexes with tert-butyl chloride, which complexes block the further interaction between chloroalkanes and activated aluminium. The aluminium chloride complexes obtained were studied for the case of isobutane alkylation by butenes.

A new approach is proposed to the preparation of highly active bifunctional catalysts for hydrogenation processes providing an increase in the conversion level of oil refining to produce motor fuels in accordance with contemporary international standards. This approach is based on the preparation of a carrier containing acidic components, as well as on targeted selective synthesizing an active component for the hydrogenolysis and hydrogenation reactions such as Co(Ni)-Mo(W)-S phase. The latter is localized in the structure of the catalyst so that it is available for all the raw material components liable to catalytic transformations. The method of preparation is based on an in-solution synthesis of bimetallic compounds, the precursors of the active component. Within the framework of the approach proposed, highly active catalysts can be prepared, designed for hydrocracking and hydrorefining of various petroleum distillates.

Basic principles are considered concerning the action of photocatalysts in deep oxidation of organic compounds containing in air. Within the framework of the Langmuir-Hinshelwood model, kinetic parameters were calculated concerning the photo-oxidation process for a number of substances (the rate constant and adsorption constants) were then used for designing reactors for air purification. It is demonstrated that for increasing the rate of photocatalytic oxidation it is necessary to optimize the geometry of a photocatalytic filter, as well as to use inorganic air-penetrable materials (glass fibre cloth and foamed ceramics) as carriers for a photocatalyst. In addition, the efficiency of air purification could be enhanced through the use of multi-stage reactor wherein air under purifying passes successively the stages of electrostatic filtration, adsorption and photocatalytic treatment. An example of the proposed concept of multi-stage air purification was demonstrates at the Luch Co. (Novosibirsk).

Urgent directions in mastering the methods of chemical processing of plant biomass and in the development of new methods of integrated utilization of its major components - polysaccharides, lignin, and extractive substances are considered for research work carried out at the Institute of Chemistry and Chemical Technology, SB RAS (Krasnoyarsk, Russia)) as example. Some processes are described that have been developed for utilization of wood waste material resulting in obtaining valuable chemical compounds (levulinic acid, glucose, xylose, aromatic aldehydes, biologically active compounds), important material (cellulose, biodegradable polymers, sorbents) and liquid fuel.