A study of the uptake of thorium onto zeolites
The presence of the a- and S- emitters, uranium and thorium, in industrial waste streams poses a serious threat to the environment. This is due to both the potentially damaging nature of the radioactive emissions when incorporated into biological systems and to the general toxicity of these heavy metals. A programme of work to remove these heavy metals especially thorium, from a particular raffinate was undertaken. It was desirable to use zeolites specifically to remove thorium and some uranium. A survey of the uptake of thorium onto a ndide range of zeolites, both natural and synthetic is included. It was necessary to find a zeolite which could take up the radioactive cations, resist acid attack and which was suitable for use in a large scale, industrial removal plant. Due to the nature of the radiochemical components in conjunction with zeolite behaviour, several radiochemical techniques had to be modified to provide analytical methods for this project. Effects of competing cations on the uptake of thorium onto zeolites were also studied. The best all-round candidate was found to be an Eastgate zeolite, although clinoptilolite showed a reasonable uptake of thorium. The work carried out attempted to elucidate the mechanisms of thorium removal from solution.