Selective Removal of Cs⁺ by Synthetic Micaceous Ion Exchangers

Abstract

The cation-exchange characteristics of Na-substituted taeniolite (NaT) and Na-substituted hectorite (NaH) for Cs⁺ were investigated in aqueous solutions at 25°C. These synthetic fluoromicas swell in water. Cs⁺ exchange reaction on NaT appeared to attain steady states within 8 h. The most uptake amount of Cs⁺ on NaT was 1.15 mmol/g. The Na⁺⇔Cs⁺ exchange isotherm on NaT rose steeply and reached a plateau above the diagonal line in the lower concentration region. It was found that NaT had high selectivity for Cs⁺ in the low concentration region of Cs⁺. The distribution coefficient, K_d, for Cs⁺ on NaT under a large excess of Na⁺ or Ca²⁺ was 4.7×10⁴ml/g and 3.1×10⁶ml/g, respectively. NaT takes up Cs⁺ from mixed solutions of large amount of Na⁺ or Ca²⁺and small amount of Cs⁺. These results suggest that NaT is useful for separation and immobilization of Cs⁺.