Sorption and separation studies of thorium(IV) in L-valine medium using poly(dibenzo-18-crown-6)

A simple method has been developed for the separation of thorium(IV) in L-valine medium using poly(dibenzo-18-crown-6) and column chromatography. The sorption of thorium(IV) was quantitative from 1x10-4 to 1x10-1 M L-valine. Amongst the various eluents 0.5-8.0 M hydrobromic acid, perchloric acid, hydrochloric acid and 0.5-5.0 M sulfuric acid were found to be efficient eluents for thorium(IV). The capacity of poly(dibenzo-18-crown-6) for thorium(IV) was 0.258 mmol/g of crown polymer. Thorium(IV) was separated from number of cations and anions in binary mixtures. Most of the cations and anions showed very high tolerance limit. Selective separation of thorium(IV) was possible from uranium(VI), cerium(III) and lanthanum(III). The method was extended to determine thorium(IV) from geological and industrial samples. (author)