EXAFS investigation of strontium adsorption onto weathered biotite

Honda, Mitsunori   ; Kaneta, Yui ; Yaita, Tsuyoshi

The efficiency of the sorption of Sr on weathered biotite, a type of clay minerals was investigated. Removal of Sr and Cs is important in the treatment of contaminated water from the 1F accident, which is one of the radionuclide waste treatment problems. We focused on developing an adsorption method for Sr ions using weathered biotite, which are abundant in Fukushima. Applying a molten salt treatment, the amount of sorbed Sr simply increased as the added mass ratio of strontium chloride (SrCl) increased from 1:1, 1:5, and 1:10 for the one-fold, five-fold, and ten-fold additions of SrCl, respectively. Then, the crystal structure of weathered biotite as an adsorbent was evaluated by X-ray diffraction (XRD) analysis. Thus, it was observed that the WB retained its original crystal structure even after the sorption of Sr. Extended X-ray absorption fine structure (EXAFS) analysis was performed to investigate the local sorption structure of Sr in the WB. The results revealed that Sr was preferentially sorbed into the SiO and AlO layers when Sr was in the low mass ratio, while, it was mainly sorbed into the SiO layer when the ratio was high.