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Abstract  

The sorption of chromium(III) and chromium(VI) on lead sulfide has been investigated in dependence on pH, time of sorption and the concentrations of sorbate and sorbent. The mechanisms of the sorption of Cr3+ and CrO 4 2– traces on lead sulfide are discussed; a difference between CrO 4 2– sorption on PbS and -Fe2O3 has been found. Sulfates and molybdates affect the removal of chromates from aqueous solutions. Lead sulfide carrier prepared in this work was also used for the preconcentration of chromium(III) and chromium(VI) from tap water.

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Equilibrium and metastable solid solutions of binary mixtures of BaSO4−CaSO4 and SrSO4−CaSO4, and sorbents based on mixtures of compounds in the systems BaSO4−MgSO4 and SrSO4−MgSO4 were prepared by special heat treatments. The sorption properties of such systems were studied in relation to their structural characteristics. A positive effect of the dynamic reconstruction of the lattice on the sorption of strontium ions was found in all cases. Good sorption properties were found for the systems BaSO4−CaSO4 and BaSO4−MgSO4 An effort was made to explain the mechanism of sorption on such systems, using several independent methods.

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The chromatographic behaviour of Hg(II), methylmercury, phenylmercury and Cu(II) on three different sorbents, strong acidic sulfobutyl cation-exchanger, weak basic aminopropyl anion-exchanger and silicagel has been studied. A dithizone solution in cetyltrimethylammonium hydrogensulfate water micellar medium was found as a useful post-column derivatization reagent for UV-VIS detection. The detection limits 1.1 ng, 2.2 ng, 6.2 ng and 1.6 ng were found in silicagel chromatographic system and dithizone detection system for Hg(II), methylmercury, phenylmercury and respectively for Cu(II).

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Iodide retention by AgCl, a potential sorbent in high-level waste (HLW) storage systems, was determined. The kinetics and steady state sorption of iodide were determined in single and mixed electrolytes of NaNO3, and NaCl at ionic strengths of 25 and 50 mM. Iodide retention involved the conversion of AgCl to AgI. This conversion increased rapidly within 0.02 hours, and retention maxima of 0.92 and 1.0 mol·l·mol−1 Ag occurred for low and high ionic strengths, respectively. These short-term studies indicated that AgCl would be an effective scavenger of I in HLW containment systems.

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Abstract  

Reduction of carbon dioxide (CO2) in the environment may avert the effects of global warming. One method to control CO2 emissions is to sequester it underground. Leakage from storage must be minimized for long-term control. Detection of leaks decreases the amount of CO2 released from storage, so onsite monitoring must be performed over large areas. Spiking the injected CO2 with an isotopic tracer can improve ground leak detection using fewer sampling stations, with greater accuracy than CO2 sensors and no interference from radon gas. The relative merits of sorbent materials, isotopic tracers, detection methods and potential interferences will be discussed.

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In this work, Cs+ ion sorption on some clays and zeolite were investigated. 137Cs was used as a tracer. Activities were measured with a NaI crystal gamma counter. The particle size distribution was determined by a laser sizer. Surface area of the particles were determined by BET (Brunauer, Emmett and Teller method). Structure analysis was made by using X-ray diffraction. The chemical compositions of the solid samples were determined using a ICAP-OE spectrometer. Kinetic and thermodynamic parameters were determined. Due to very high uptake results; clay and zeolite can be proposed as a good sorbents in waste management considerations.

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The effect of humic acid addition on the capacity of inorganic sorbents to sorb radioactive cesium and strontium was studied on montmorillonites in a calcium and potassium form. The Sips isotherm for humic acid sorption and multisite distribution model of ion sorption was found to suit well for the description of mobility of ions as a function of equilibrium humic acid concentration as a single variable at given pH and type of silicate. Complexation of the ions was of minor importance at the conditions investigated. Influence of humic acid on the specific radiocesium interception potential (SRIP) was also evaluated.

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Abstract  

A standard analytical technique for determination of the partial ion exchange capacity of mineral or soil for selective uptake of cesium, the specific radiocesium interception potential (SRIP) is formulated and theoretically discussed. The method is based on the determination of a retained, leached or sorbed fraction of carrier-free cesium-137 in soil contacted with 0.01M KNO3-0.01M Ag thiourea complex solution at the phase ratio solution:sorbent 10 ml:0.1 g. Reliability of the method is discussed in connection of radiocesium carrier and humic substances presence.

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Abstract  

Feasibility of using fixed bed column of conventional ion exchangers/sorbent and chemical precipitation based processes have been examined for the effective removal of the very low levels of 106Ru activity from NH4NO3 effluent generated during wet processing of rejected sintered depleted uranium fuel pellets. Based on the results, a simple process involving precipitation of cobalt sulphide along with ferric hydroxide was selected and further optimization of process variables was carried out. The optimized process has been found to be highly efficient in reducing 106Ru activity down to extremely low levels.

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Abstract  

The sorption of uranium from acidic aqueous solutions (pH 4.5, C init = 10 to 1000 mg U/L) by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa was investigated using a batch technique. The U-sorption onto Saccharomyces cerevisiae and Debaryomyces hansenii followed a Langmuir, while that onto Kluyveromyces marxianus and Candida colliculosa a Freundlich isotherm. The results demonstrated that all investigated biomasses could effectively remove uranium from acidic aqueous solutions. From all sorbents, Saccharomyces cerevisiae appeared to be the most effective with a maximum sorption capacity of 127.7 mg U/g dry biomass.

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