Column chromatographic separation of thorium(IV) from associated elements using poly-(dibenzo-18-crown-6) from sodium nitrate medium

A simple column chromatographic method has been developed for the separation of thorium from associated elements using poly-(dibenzo-18-crown-6). The separations are carried out from sodium nitrate medium. The adsorption of thorium was quantitative from 0.1-0.5M sodium nitrate. Amongst the various eluents tested, 1.0-8.0M HCl, HBr, H2SO4 and 3.0-8.0M HClO4 were found to be particularly efficient for the elution of thorium. The capacity of poly-(dibenzo-18-crown-6) for thorium was found to be 1.034 mmole/g of crown polymer. Thorium was separated from number of elements in binary mixtures in which most of the elements showed a very high tolerance limit. It was possible to separate thorium from a number of elements in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand and gas mantles. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%). (author)