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  • Author or Editor: S. Kilinç x
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Abstract  

The sorption and desorption of thorium on a West Anatolian montmorillonite has been studied by application of a batch technique. Experimental procedures are outlined and results for thorium contacted with montmorillonite are reported and discussed. The thorium concentration range was between 200–4000 ppm (8.5×10–4–1.7×10–2M). The sorption and desorption coefficients varied between 1.586–0.216 ml g–1 and 0.829–0.168 ml g–1, respectively, and sorption was not fully reversible. The data could be fitted to Freundlich and Langmuir isotherms. The quantity of the sorbed thorium was much lower than its theoretical CEC. This was attributed to a blocking of montmorillonite's CEC by thorium islands in the interlayer.

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Abstract  

The possibilities of preparing a packing for reversed phase column chromatography from Menderes' perlite were studied. Its physical and chemical characteristics were compared with other solid supports prepared from rocks, such as perlite and volcanic slags. A series of chemical treatments were applied to improve the mechanical and chemical properties of perlite. The experimental work covers the strong acid treatment, the strong base treatment and the silanization with DMCS. The raw perlite containing 70–73% SiO2 was treated with NaOH to make soluble silicates and to increase it. Thus the surface and mechanical characters of the modified perlite were determined. The mean surface OH group density and the specific surface area were 3.2 μmol/m2 and 9.2 m2/g, respectively. The modified perlite was silanized and hydrophized to load organic complexing agents. The TBP was fixed successfully on perlite up to 20% w/w. The packing prepared was used to study the chromatographic behavior of UO2 2+ Fe3+.

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Abstract  

The sorption and desorption of uranium, thorium and mercury on a western Anatolian montmorillonite, obtained from the deposit located in Kula, were studied by application of a batch technique. The clay used is a tertiary clay originally found in a rather large geological formation of west Anatolia. It is nearly pure montmorillonite. Its cation exchange capacity (CEC) determination was performed for ammonium acetate by the Mehlich procedure. The mean CEC was found to be 83 meq/100 g, which, taking into account that CEC determinations were carried out on unfractionated material, is in good agreement with previously reported data. The concentration ranges were between 70–1500 ppm for mercury and 100–2000 ppm for thorium and uranium. The relative importance of test parameters, e.g., pH, clay particle size, groundwater composition, contact time and solid/water ratio, which determine the distribution coefficients was studied. The sorption coefficients varied between 2.7–6.4 ml/g for U, 0.22–1.59 ml/g for Th and 152.4–427.2 ml/g for Hg. The differences of distribution coefficients are discussed. The data could be fitted to Freundlich and Langmuir isotherms. The quantities of the sorbed and desorbed Th were much lower than its theoretical CEC's. This attitude was attributed to the blocking of montmorillonite by cation islands sorbed in the interlayer. Hg is sorbed most strongly. The experimental results indicate that the montmorillonites studied should be effective components of the buffer and backfill material and lead to eventual immobilization of these elements, which are environmentally dangerous.

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