Electrochemical Cs removal and crystal formation from Fukushima weathered biotite in molten NaCl-CaCl<sub>2</sub>

M. Honda; T. Goto; Y. Sakanaka; T. Yaita; S. Suzuki; M. Honda; T. Goto; Y. Sakanaka; T. Yaita; S. Suzuki

doi:10.3934/ElectrEng.2019.2.102

AIMS Electronics and Electrical Engineering

2019, Volume 3, Issue 2: 102-110. doi: 10.3934/ElectrEng.2019.2.102

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Research article

Electrochemical Cs removal and crystal formation from Fukushima weathered biotite in molten NaCl-CaCl₂

1.
Materials Sciences Research Center (MSRC), Japan Atomic Energy Agency (JAEA), 2-4, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
2.
Department of Science of Environment and Mathematical Modeling, Graduate School of Science and Engineering, Doshisha University, Kyoto, 610-0321, Japan
3.
Fukushima Environmental Safety Center, Japan Atomic Energy Agency (JAEA), 6-6 Sakae-machi, Fukushima-shi, Fukushima 960-8031, Japan

Received: 28 November 2018 Accepted: 03 March 2019 Published: 19 March 2019

The possibility of removal and controlling crystal formation from weathered biotite (WB) in clay minerals were investigated using molten salt electrochemistry (EC) in molten NaCl-CaCl₂ under an electrochemical reductive reaction. Cyclic Voltammogram (CV) measurements were performed in the range of +0.5 V to −2.2 V. Several peaks were confirmed in the CV spectra. The peak at −1.4 V represents a reduction reaction of Fe in WB, so we conducted an experiment at −1.4 V for 2 h to reduce Iron (Fe). The Cs removal rate after EC treatment was determined by X-ray fluorescence analysis, and almost 100% Cs removal was confirmed. To understand the effect of the reductive reaction, we performed X-ray Adsorption Fine Structure (XAFS) analysis. Before EC treatment, the Fe in WB was present as a mixture of Fe³⁺ and Fe²⁺. After EC treatment, the presence of Fe²⁺ was confirmed by XAFS analysis. Based on this finding, EC treatment is effective for reducing Fe in WB. This result indicated that Fe₂O₃ formation was suppressed, and the reduction reaction was effective for controlling crystal formation.
- molten salt,
- electrochemistry,
- X-ray analysis,
- Fe,
- clay mineral
Citation: M. Honda, T. Goto, Y. Sakanaka, T. Yaita, S. Suzuki. Electrochemical Cs removal and crystal formation from Fukushima weathered biotite in molten NaCl-CaCl2[J]. AIMS Electronics and Electrical Engineering, 2019, 3(2): 102-110. doi: 10.3934/ElectrEng.2019.2.102

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Abstract

The possibility of removal and controlling crystal formation from weathered biotite (WB) in clay minerals were investigated using molten salt electrochemistry (EC) in molten NaCl-CaCl₂ under an electrochemical reductive reaction. Cyclic Voltammogram (CV) measurements were performed in the range of +0.5 V to −2.2 V. Several peaks were confirmed in the CV spectra. The peak at −1.4 V represents a reduction reaction of Fe in WB, so we conducted an experiment at −1.4 V for 2 h to reduce Iron (Fe). The Cs removal rate after EC treatment was determined by X-ray fluorescence analysis, and almost 100% Cs removal was confirmed. To understand the effect of the reductive reaction, we performed X-ray Adsorption Fine Structure (XAFS) analysis. Before EC treatment, the Fe in WB was present as a mixture of Fe³⁺ and Fe²⁺. After EC treatment, the presence of Fe²⁺ was confirmed by XAFS analysis. Based on this finding, EC treatment is effective for reducing Fe in WB. This result indicated that Fe₂O₃ formation was suppressed, and the reduction reaction was effective for controlling crystal formation.

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