N. A. Klimenko

Structural and sorption properties of activated carbon modified with iron oxides

The structural and sorption characteristics of activated carbon modified with iron oxides were investigated and static exchange capacity of its surface functional groups of basic and acidic nature was determined. The modification of carbon with iron oxides was found to result in insignificant (7–13%) reduction of micropore and mesopore volume and in basification increase of the sorbent surface. The modified activated carbon is highly efficient in removing phenolic compounds from water.

Adsorption-catalytic removal of fulvic acids on activated carbons in the presence of hydrogen peroxide

We have investigated the impact of the change of the chemistry of the activated carbon surface on the parameters of equilibrium adsorption of fulvic acids from aqueous solutions on carbon in the presence of hydrogen peroxide. The article has considered the possibility of a multicomponent approach to the description of adsorption equilibrium when using, ay least, two hypothetic components in the Freundlich equation. For qualitative assessment of adsorbability from a multicomponent blend of organic matter we proposed to use a notion about “a conditional component”. It is shown that when introducing into the solution of fulvic acids of hydrogen peroxide the adsorption degree of fulvic acids on activated carbon substantially increase due to the catalytic effect of oxidizing organic matter.

The effect of preliminary ozonization on the bioregeneration of activated carbon during its long-term service

The activated carbon (AC) bioregeneration was shown to proceed more efficiently during the filtration of preozonized tap water as compared with bioregeneration under the similar conditions during the filtration of non-ozonized water. The enhanced efficiency of AC bioregeneration after the filtration of preozonized water is determined by transformation of the total organic carbon into a better biodegrading form, increased microbiological activity in the depth of AC bed, and enhanced hydrophilicity of the AC surface area due to its chemical interaction with dissolved ozone.

Seasonal variations of characteristics of organic matter in the Dnieper River water

The paper assessed characteristics of natural organic substances of the Dnieper River (Kiev) by seasons of the year based on determination of such parameters as total organic carbon, absorption in the ultraviolet region (UV254), specific absorption (SUVA), and color. It has been shown that in different seasons of the year the water in this region is characterized by average values of SUVA and a rather high content of total organic carbon.

Sorption of ions of U(VI) and strontium by biosorption based on Bacillus polymyxa IMV 8910 in aqueous systems

We have investigated the influence of individual components of waters (humic acids, anions, and cations) on sorption of ions of U(VI) and strontium by the biosorbent based on the Bacillus polymyxa IMV 8919 cells. It is shown that during transition to real aqueous systems there occurs a decrease of the degree of extracting U(VI) and strontium by a microbial sorbent. Extraction of strontium in a great degree depends on the concentration in water of bivalent cations, which may compete with it in the sorption processes. A degree of purification of U(VI) is mainly determined by the pH of the medium. Acidification of aqueous media containing uranium, up to pH 5 makes it possible to raise the degree of extraction of metals by means of a biosorbent

Adsorption and heterogeneous catalytic oxidation of organic matter in aqueous solutions

The paper presents an analytical review of the possibility of combination and adsorption and the heterogeneous catalysis on the interface in the aqueous medium. Covered are issues on the heterogeneous catalysis on activated carbon in the presence of hydrogen peroxide. The paper has investigated the decomposition mechanisms of hydrogen peroxide in the presence of a sorbent. The article has considered the role of organic matter on active carbon with a biofilm, It has shown the possibility of intensifying the processes of adsorption and the heterogeneous catalysis by modifying the carbon surface.

The impact of surface chemistry of activated carbon and its structure on adsorption of fulvic acids from aqueous solutions

We have quantitatively assessed the impact of surface chemistry and the structure of activated carbon on adsorbability of fulvic acids from aqueous solutions. For assessing adsorption energy of different fractions of fulvic acids the method of “conditional component” was used. It has been shown that in the first approximation in the solution of fulvic acids one can separate weakly- and strongly adsorbing fractions. It has been found that the change of energy heterogeneity of the surface of activated carbon as a result of oxidation leads to the reduction of adsorption energy of fulvic acids and an increase of the concentration range of the conditional share of the weakly adsorbing fraction.

Phylogenetic diversity of aqueous microorganisms separated after the advanced tertiary of tap water

The species composition of bacterial community of the drinking tap water and water samples taken at different purification stages of the water conditioning plant at an enterprise producing special drinks has been analyzed. This study involves the analysis of 16S rRNA gene sequences and the use of molecular biology methods based on the phylogenetic analysis. The following bacterial species were identified: Bacillus nanhaiensis, Brevibacterium frigoritolerans, and Lysinibacillus fusiformis. All the studied strains belong to phylum Firmicutes, class Bacilli representing Gram-positive microorganisms that are not pathogenic to human. The presence of the bacteria investigated in different habitats such as the drinking chlorinated water, in the presence of stress factors (arid climate, high or low temperatures, depleted soil, and the occurrence of disinfectants) indicates their ability to easily adapt to new living conditions expanding their habitat.

Removal of aromatic compounds from water on biologically activated carbon

We have carried out an assessment of the content of aromatic compounds (o-nitrophenol, o-aminobenzoic acid) in grains of activated carbon of a biofilter at the stage of stationary water treatment. It was found that the removal degree of aromatic compounds by the biofilm of biologically activated carbon in great measure is determined by the value of the decreasing of Gibbs free energy of adsorption (−ΔGa). It is shown that due to the competing action of the biofilm part of the accessible surface of activated carbon is not used for adsorption of organic matter.

The impact of aromatic compounds on the efficiency of biofiltration through activated carbon

The article has investigated the sorption process on activated carbon of aromatic compounds with different functional groups (o- nitrophenol, o-aminophenol, aniline). We have showed the possibility of assessing the efficiency of biofiltration depending on such factors as the variation of the Gibbs free energy of adsorption of sorbates and the value of the specific load of an organic substance on activated carbon. For determining a contribution of the biological component to the total efficiency of the process we used the value of the ratio between the specific dynamic adsorption to the specific equilibrium adsorption at uniform loads in terms of the organic matter on biologically activated carbon.