Mechanism of Cs Removal from Fukushima Weathered Biotite by Heat Treatment with a NaCl–CaCl2 Mixed Salt
| Autor: | Iwao Shimoyama, Mitsunori Honda, Shinichi Suzuki, Yoshihiro Okamoto, Tsuyoshi Yaita, Hideaki Shiwaku |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
In situ
chemistry.chemical_classification 010504 meteorology & atmospheric sciences Extended X-ray absorption fine structure Chemistry General Chemical Engineering Structure function Salt (chemistry) General Chemistry 010501 environmental sciences engineering.material 01 natural sciences Fluorescence Article lcsh:Chemistry lcsh:QD1-999 engineering Absorption (chemistry) Biotite 0105 earth and related environmental sciences Nuclear chemistry |
| Zdroj: | ACS Omega, Vol 2, Iss 2, Pp 721-727 (2017) ACS Omega |
| ISSN: | 2470-1343 |
| Popis: | An in situ extended X-ray absorption fine structure (in situ EXAFS) spectroscopic analysis at high temperature was conducted to investigate the mechanism of Cs removal from weathered biotite (WB) from Fukushima, induced by heating with a mixed salt of NaCl and CaCl2. This indicated that most Cs remained in WB during heating at 200–700 °C. In addition, the in situ EXAFS spectra gradually changed on heating with the mixed salt and a completely different spectrum was observed for the sample after cooling from 700 °C to room temperature (RT). Ex situ EXAFS measurements and X-ray fluorescence analyses were also conducted on samples after heat treatment and removal of the mixed salt to clarify the temperature dependence of the Cs removal ratio. On the basis of the results of radial structure function analysis obtained from in situ EXAFS, we concluded that almost all of the Cs was removed from WB by heating at 700 °C with the mixed salt, and that Cs formed Cs–Cl bonds after cooling to RT from 700 °C. In contrast, although more than half of the Cs present was removed from WB by heat treatment at 500 °C, most Cs was surrounded by silica tetrahedrons, maintained by Cs–O bonds. On the basis of these results, different Cs removal processes are suggested for the high-temperature (600–700 °C) and low-temperature (400–500 °C) regions. |
| Databáze: | OpenAIRE |
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