Home – Home – Jornals – Chemistry for Sustainable Development 2006 number 1

Kinetics and equilibrium of the sorption of Cu(II), Zn(II) and Cd(II) ions on a natural cellulose-containing material

A direct atomic emission method developed for measuring mercury content in powder carbon adsorbents is shown to perform the simultaneous analysis of nuisance admixtures. It provides an express control of mercury content in carbon based modified adsorbents (CMA) used for mercury removal from wastewaters. Analysis accuracy is improved due to simultaneous calculations using several analytical lines of the element, mercury content range being 0.0001

Sorption properties of various kinds of hydrolytic lignin

Indirect electrochemical oxidation of phenol is studied in acid (pH 2

Inversion voltammetry method applying glass carbon electrode was developed for the case specific mercury control. Mercury concentration was measured in the lithium-containing solvents and in modified carbon adsorbents (MCA). In MCA mercury content was measured after weighted sample burning and mercury stripping by the H2O2 containing 1 M HCl solution. Diapason of mercury concentration measurement was 0.2

Experimental data on the dissolution of calcite in water and in the solution of sulphuric acid were treated with the help of the generalized equation of heterogeneous kinetics. The possibility of using this method to determine the kinetic characteristics of the process was demonstrated. The data on the limiting stage were obtained; rates constants of calcite dissolution under different conditions were calculated.
A procedure to calculate technological parameters of the process leading to a decrease in the level of acidation of natural water was proposed.

Nanocrystalline tin oxide films were obtained on glass and metal substrates by immersing into the solution of tin carboxylate, centrifuging of the substrate with the solution, followed by thermal treatment. A distinguishing feature of the proposed method is the use of extraction for the synthesis of precursors, which allows us to obtain the precursor material free from any impurities. It was established that the sensitivity of tin oxide films to the gases depends on pyrolysis temperature and is maximal for the films pyrolyzed at 400 oC.

Dynamics of the accumulation of oxygenated groups during coal ozonation in chloroform is investigated. It is shown that the oxygen content of the organic matter of coal is determined by the availability of reaction centres for ozone molecules. High-molecular water-insoluble acids prevail among coal ozonation products.

A flow reactor was used to study the kinetics of 5-hydroxymethylfurfural synthesis from fructose and sucrose at 240 oC in water solutions containing acetic and phosphoric acid as catalysts. The maximum yield of 5-hydroxymethylfurfural was found to be practically independent of the chosen catalyst and carbohydrate. It attained 40 mol. % at 240

Influence of the water content of milling medium on the properties of reaction bonded aluminium oxide powder precursors and their sintered mechanical properties is studied. As a result of interaction between absolute ethanol and aluminium, the water content of the mixture milled in absolute ethanol increased to 4.7 %. Mechanical properties such as bending strength and toughness of the sintered ceramics depend on the water content of the powder precursors. Higher bending strength, 350 MPa and toughness, 3.7 MPa m1/2 were observed in the sample milled in absolute ethanol. Higher water content of the mixture milled in absolute ethanol is the main reason of the high mechanical properties.

Initial stage for preparing alumina supported metal catalysts according to a scheme, essentially reducing harmful wastes, is discussed. Preparation method is based on a direct interaction of pretreated metallic aluminum with water. Diffusion phenomena are shown to be the core of aluminum activation by metallic In

Liquid products of the autoclave hydrogenation and hydropyrolysis of the Barzas sapromixite were studied. Chromatomass spectrometry was used to determine the content of individual substances in the low boiling fractions. Hydropyrolysis product appeares to consist of normal paraffins by more than 50 mass %. Hydrogenation products is characterized by a higher content of cyclic and structure isomerized paraffins. Aromatics content in both products does not exceed 14.1 mass %. IR and NMR spectroscopy show that fractions boiling above 180 oC contain mostly aliphatic fragments. Hydropyrolysis products composition is similar to that of oil, while hydrogenation product is characterized by more aromatic and shorter aliphatic fragments per statistically average molecule. If mechanically activated iron ore catalyst is used at the sapromixite hydrogenation and hydropyrolysis, the contribution of distillate fractions increases, and low boiling (boiling start 180 oC) fractions contain more low molecular mass hydrocarbons.

The behaviour of phosphate anion

Sulphuric acid leaching of sulphide ores assisted by nitrous compounds in Udokan copper deposits was studied regarding the effect of low and high temperatures. Negative temperatures were found to intensify the leaching of copper dramatically. Nitrous acid appears to be the catalyst of the process. Experimental results show that heavy metals in the cryogenic zones of sulphide ores demonstrate high mobility at oxidation processes assisted by nitrous compounds.