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A new series of calix[4]pyrrole derivatives bearing azo-moiety at the mesoposition of the macrocycles have demonstrated the ability for liquid-liquid extraction, preconcentration and transport of Th(IV) across a liquid membrane. Various significant extraction parameters such as effect of pH, effect of solvent and effect of reagent concentration were investigated, which showed high affinity and selectivity towards Th(IV) in the presence of large quantities of associated metal ions. The wavelengths of maximum extraction ( max) and molar absorptivity ( ) have also been determined. The stoichiometry of complex was evaluated by Job s plot method, linear concentration range obeying Beer s law, effect of diverse-ions have also been studied. Liquid membrane transport studies of Th(IV) were carried out from source to the receiving phase under controlled conditions and a mechanism of transport is proposed. The validity of the proposed method was checked by determination of analyte ions in certain standard and natural geological samples.

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Dr. Hrishikesh S. Gupte (M.Sc., Ph.D, Chemistry) working as Research Associate at Department of Chemistry, Gujarat University, Ahmedabad, Gujarat, India

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