Phosphate treatment of carbonaceous clays increased the uptake capacity for uranium and thorium. Heat treatment up to 400°C
improved enormously the uptake property of the treated clay. These treatments failed to improve the uptake quality of argileous
clays. Strontium exchanges weakly with clays of high Ca and Mg contents but strongly with a silicoaluminium clay of low Ca
and Mg contents. A mixed bed of these two clays was found adequate for decontamination of actinides and fission products.