Molten salt electrochemical Cs removal and crystal formation from weathered biotite toward energy material creations

溶融塩電気化学法による福島風化黒雲母からのCs除去とエネルギー材料創製へむけた結晶創製

本田 充紀   ; 後藤 琢也*; 鈴木 伸一; 矢板 毅

Honda, Mitsunori; Goto, Takuya*; Suzuki, Shinichi; Yaita, Tsuyoshi

Microscopic structure and behavior of cesium-containing weathered biotite are investigated by various techniques based on X-ray analyses. The samples are treated in molten salt consisting of NaCl and CaCl at a temperature of 700C with a reductive potential of -1.4 V being applied. Efficient removal of cesium followed by formation of new phases of clay minerals is observed through their X-ray diffraction spectra. The local structure of iron (Fe) is confirmed through the X-ray adsorption fine structure (XAFS) analysis. Oxidation state of Fe is found to change from an initial mixed state between Fe and Fe to the final state with Fe through XAFS spectra. Interestingly, Scanning Thermal Probe Micro image measurement has elucidated that some of the new phases of clay minerals show extremely large Seebeck coefficient. This result may open up a new way to produce efficient thermoelectric materials.