Home – Home – Jornals – Chemistry for Sustainable Development 2011 number 4

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.