Local structure around cesium in montmorillonite, vermiculite and zeolite under wet condition

Tsuji, Takuya  ; Matsumura, Daiju   ; Kobayashi, Toru ; Suzuki, Shinichi; Yoshii, Kenji  ; Nishihata, Yasuo; Yaita, Tsuyoshi

We have observed the local structure around cesium in silicate minerals under wet and dry conditions by using X-ray absorption fine structure (XAFS) technique at Cs -edge. The measurements under wet and dry conditions simulated changes of the actual environment. High transmission ability at Cs -edge provides XAFS measurement under various conditions. Montmorillonite, vermiculite, and zeolite were employed for the study. Vermiculite was obtained by wet classification of the actual soil at Fukushima. The result of XAFS measurement shows that water molecules in interlayer position are removed by cesium adsorption in the interlayer site of vermiculite. Cesium ion was adsorbed on one side of the interlayer site of swelled montmorillonite under wet condition. On the other hand, water molecules were not coordinated with cesium ion in the zeolite even in the case of wet condition.