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Abstract  

Thermal stability of silica-polyvinylsiloxane systems with different ratio of hydrophilic and hydrophobic components and its forms with adsorbed dyes were studied using thermochemical method. It was shown that the maximum of endoeffect relating to dehydroxylation of sorbents surface is observed at 325C. The maximum temperature of the second endoeffect depends on the organosilica sorbents composition and increases with a decrease of hydrophilic and hydrophobic sites ratio. It was found that the values of the summary thermal effect lowers upon the raise of the quantity of silanol groups. It was shown that thermal stability of composition materials is higher in comparison with initial organosilica sorbents.

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Introduction Organoclay-based nanocomposites obtained by modifying Na-smectites with quaternary ammonium cations are potential candidates for serving as sorbents of different organic molecules [ 1 – 3 ] and are used in cleaning

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carbonaceous sorbents) is expected to be ion exchange [ 11 ], though there might be some additional mechanism for N-doped aerogels, which can enlarge sorption capacity (e.g. complexation). Moreover, aerogel prepared by the adding 3-hydroxypyridine

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Abstract  

Racemic tritium-labelled amino acids were separated into optical isomers by chromatography on a chiral polyacrylamide sorbent filled with copper ions. The polyacrylamide sorbent is synthesized by Mannich's reaction through the action of formaldehyde and L-phenylalanine upon polyacrylamide Biogel P-4 in an alkali phosphate buffer. Tritiumlabelled amino acids are eluted by a weak alkali solution of ammonium carbonate. Data are presented on the ligand exchange chromatography of amino acids depending on the degree to which the sorbent is filled with copper ions and on the eluent concentration. Conditions are suggested for the quantitative separation of amino acid racemates. Amino acids are isolated from the eluent on short columns filled with sulfonated cation exchanger in the H+ form. HPLC on modified silica gel sorbents is also used for the analysis of tritium-labelled optically active amino acids. Amino acids are eluted by a weakly acidic water-methanol solution containing ammonium acetate. UV and scintillation flow type detectors are used.

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Summary  

The sorption of uranium-Arsenazo III complex was studied using Dowex-1x8 and carbonized apricot stone. The results show a similarity between the two sorbents since the percentage uptake of a uranium complex in the ratio 1 : 1 reaches 100% and 92% on the Dowex-1x8 and the carbonized apricot stone, respectively. Also the uptake of the complex on either sorbents increases with increasing the hydrogen ion concentration to reach  a maximum value at pH 2.5. The two sorbents are used to study the sorption of uranium(VI) from seawater in the presence of 0.002% of Arsenazo III and 10-3M EDTA, where it is found that uranium is completely sorbed by the two sorbents.

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Abstract  

Various sorbents recommended for solid phase extraction (SPE) in sample preparation procedures were studied for use in combination with capillary isotachophoresis (ITP). They were very efficient in achieving trace concentration levels (low ppb, i.e., low parts per 109) for different types of ITP analytes present in environmental and biological matrices. A macroporous carbon sorbent was convenient for sample preparation in ITP analysis of short chain fatty acids (C4–C9) in drinking water. Chelating sorbents based on hydroxyalkyl methacrylate matrix with salicylate, thioglycolate and 8-hydroxyquinolinate functionalities were found to be very suitable for preconcentration of heavy metals with an inherent sample clean-up. An octadecyl-bonded silica sorbent enabled in ITP a photometric detection of -aminobutyrate (labeled with a 2,4,6-trinitrophenyl group) at concentrations considerably lower than required for the determination of this amino acid in cerebrospinal fluid (5·10–8 mol/l).

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Abstract  

Polyether type polyurethane foams (PU) are regular stacks of solid quasi-spherical membranes produced by the reaction of polyisocyanates with polyols of polyether nature in the presence of a catalyst and a blowing agent. Contrary to conventional membrane separations, where a solid membrane is merely a differentially separating agent, or a transport medium, PU foams, apart from separation and preconcentration, also retain, i.e., sorb the species on, or in the membranes. Therefore, PU foam membranes can be considered to act as true sorbents. The membrane properties of PU foam sorbents offer unique advantages over conventional bulk type granular sorbents in rapid, versatile and effective separations and preconcentrations of different compounds from fluid samples. Unloaded PU foam sorbents have received considerable attention in the separation of different trace inorganic species.

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Abstract  

The ion-exchange equilibrium of cesium and strontium ions on clinoptilolites from different deposits — Dzegvi and Tedzami /Georgian SSR/, Beli Plast and Beli Bair /Bulgaria/ in different cationic forms of the sorbents /natural, sodium, calcium and ammonium/ is studied. The static ion-exchange capacities are determined. The sorption isotherms are plotted and the corresponding distribution coefficients are calculated. Mechanical characteristics which are important for the assessment of the technological use of the sorbents in dynamic conditions are determined. The clinoptilolite from Beli Plast deposit has the highest capacity in comparison with the other studied zeolites. The selectivity of the clinoptilolites from Bulgarian deposits is independent of the cationic form of the sorbent while the selectivity of the Georgian clinoptilolites strongly depends on the cationic form; the selectivity of the ammonium form of Tedzami sorbent is the highest.

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Abstract  

The adsorption of colloidal trivalent iron on neutral, acid and basic Al2O3 from aqueous solution as a function of pH has been studied. The dependence of sorption of pH is characterized by a maximum, whose position depends on the nature of colloidal particles and surface properties of the sorbents. Adsorption isotherms for the given range of sorbent loading can be expressed by the Langmuir adsorption equation.

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Abstract  

Several sorbents were prepared by precipitating zirconium phosphate on activated carbon support material. The main parameters of the chemical procedure were optimized in order to obtain the highest decontamination factors which can be achieved in the case of Cs+, Sr2+ and I ions. For the characterization of the sorbents, sorption isotherms and capacity data were determined. The reproducibility of the preparation is about 10%.

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