摘要：

Caesium selectivity coefficients (k G) that were determined with respect to Na-, Mg-, Ca-, Sr- and Ba-ions, for Kent and Libby vermiculites,ranged from 4·8 to 11 (litres/mol) 1 2, much higher than those with respect to K- and NH 4-ions (0·01 to 0·06), indicating the high affinity of vermiculite for the weakly hydrated cations. Higher K G values were also found for low and extremely low Cs concentrations. Vermiculite samples were very effective in removing 137Cs from solutions containing traces of 137Cs (4 ng litre 1) and extremely higher quantities of K-, NH 4-, Na-, Mg- and Ca-ions (500 mg litre 1) . 0·5 N chloride solutions of H, NH 4, K, Na, Mg and Ca were unable to remove Cs from Cs-saturated v vermiculite samples which had undergone heating at 110°C. Significant quantities (50–65%) of fixed Cs were removed from these samples only after treatment with strong acids. The high preference and fixing ability of vermiculite for Cs suggests the use of this mineral as a radioactive Cs decontaminating agent.

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