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Abstract  

In the present work an attempt was made to obtain mineral–carbon sorbents by thermal decompositon. The mineral matrix for the sorbents (aluminium hydroxide) was based on petrochemical waste stream containing considerable amounts of aluminium chloride. Reference tests were carried out with a model solution prepared with the use of analytical grade AlCl3. Atactic polypropylene and hydrocarbon mixtures obtained in the flotation of petrochemical waste waters were used as carbon-containing raw materials. The aim of this work was to determine the adsorption and structural characteristics of the complex sorbents and to check the possibility of evaluation of their hydrophobic-hydrophilic properties.

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Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix

I. Methods of modification of properties of inorganic ion-exchangers for application in column packed beds

Journal of Radioanalytical and Nuclear Chemistry
Author: F. Šebesta

Abstract  

Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups—intrinsic, supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications.

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Abstract  

The sorption behavior of the pertechnetate anion in various solid-solution systems under aerobic conditions and pH 1.3–12.5 has been investigated. Batch techniques were employed. On most of natural minerals only surface adsorption occurs. Rs-values were no larger than 2.0 ml · g–1. Adsorption on various natural minerals and rocks such as sandstone, basalt, granite, pyrite, peat and others are comparaed with the analogous processes on artificial inorganic sorbents: titanium oxides (thermoxide-34, thermoxide-3), crystaline cadmium sulfide, zirconium phosphate, and complex inorganic sorbents: antimony oxide — silicon oxide — phosphorus pentoxide, antimony oxide — silicon oxide — aluminium oxide, lithium oxide — manganese oxide — aluminium oxide — water, lithium oxide — titanium oxide —chromium oxide — water. For comparison the sorption of Tc on some organic sorbents was included. The solubility of Tc2S7 in water was measured to be 0.257 g/l. It has been shown that preliminary irradiation of sorbents such as sandstone, peat and humic acid by -rays with doses not less than 107 rad results in the decrease of Tc(VII) sorption.

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solid phase extraction (d-SPE) is based on the addition of the sorbent material into the extract to remove the matrix concomitants. d-SPE is another novel sample preparation technique which offers unique advantages such as simplicity, low solvent use

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Abstract  

A new sorbent, polyethyleniminemethylenephosphonamidic acid (PEIPPA), was synthesized from commercially available polyethylenimine and P,P-dichlorophenylphosphine oxide. After characterization by (1H, 13C, 31P) NMR and FTIR, the new ion-exchange polymer has been investigated in liquid-solid extraction of uranium. The extraction strongly depends on the pH, initial concentration of uranium, extractant to analyte ratio (mol/mol), ionic strength of the liquid medium and their mutual interactions. Such interactions were investigated through factorial 33 experimental designs in order to achieve the best conditions of batch sorption procedure, obtaining the mutual interaction among variables and optimizing these variables. The recovery of U(VI) is almost quantitative.

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Abstract  

Sorbents that concentrate radioiodide from aqueous alkaline solutions are obtained by depositing finely divided silver in porous materials, in particular in cation exchange resins. Suitalbe materials and procedures for preparing sorbents with capacities up to about 120 mol I per ml sorbent (i.e. 40 mmol I per mol Ag) are discussed.

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New type of sorbents based on polyethers and some hydrophobic anions

I. Polyethyleneglycol-heteropolyacid sorbent in H form. Selectivity towards Cs, Sr, Ba and rare earth cations

Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Rais, P. Selucký, V. Jiråsek, and F. Šebesta

Abstract  

New type of sorbent, based on the complexing properties of polyethyleneglycols, with high selectivity for Ba and Sr is described. The dependences of Kd on the initial concentration of HNO3 for Ba, Sr, Eu, Ce, Cs and Na were studied. The capacity of two model sorbents for uptake of Cs and Sr is given. The properties of the sorbents are compared with those of the ammonium salts of heteropolyacids.

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Abstract  

In general, the amount of radiocesium sorbed by the five sorbents with 0.01 mol·dm–3 NaCl was in order zeolite > NiFeCN–SiO2 > montmorillonite > aerogel > silica gel. Addition of humic acid solution to the sorbents depressed the sorption of cesium by all sorbents, except for NiFeCN–SiO2 was not seen, with the greatest effect showing to the aerogel. The presence of humic acid resulted in an enhanced desorption of cesium from zeolite, NiFeCN–SiO2 and to a lesser extent from montmorillonite and silica gel. The order of cesium retention following desorption for both sorbent and sorbent/humic-acid mixtures was zeolit > NiFeCN–SiO2 > montmorillonite > silica gel. The presence of humic acid resulted in decreasing of distribution coefficient values for both sorption and desorption processes.

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Abstract  

A magnetic sorbent based on a mixture of magnetic iron and nickel oxides, and specific surface activation by ferrocyanide solution for enhancement of cesium adsorption is described. After equilibration of clay or soil suspension with the magnetic sorbent, the latter can be removed with exchangeable radiocesium and radiostrontium by means of magnetic separation. The distribution coefficients of the order 2·103 l/kg for cesium and 5·103 l/kg for strontium were determined. The efficiency of the sorbent was investigated in a 1% montmorillonite or soil suspension. At a soil:sorbent ratio 1:1–1:6 in the suspension, the fraction of exchangeable radiocesium in soil at a 2 hours contact was diminished from 56–59% to 48–12%, the decontamination factor of both the mobile cesium and strontium is about 3. The multistage process and sorbent recycling need further investigation.

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Abstract  

In this work a series of solid sorbents were synthesized by immobilizing liquid amines on the surface of a mesoporous alumina. The samples were chemically characterized and BET surface areas calculated from the N2 adsorption isotherms at 77 K. The CO2 capture performance of the sorbents and their thermal stability was studied by thermogravimetric methods. The effect of amine loading on the CO2 capture performance of the prepared sorbents was also evaluated. Analysis of TG-DTG curves showed that thermal stabilization of the amines is significantly improved by immobilizing them on an inorganic support. Temperature-programmed CO2 adsorption tests from 298 K up to 373 K at atmospheric pressure, proved to be a useful technique for assessing the capacity of sorbents for CO2 capture. Alumina impregnated with diethylenetriamine presented the highest CO2 adsorption capacities throughout the tested temperature range.

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