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Arai, Yoichi; Watanabe, So; Hasegawa, Kenta; Okamura, Nobuo; Watanabe, Masayuki; Takeda, Keisuke*; Fukumoto, Hiroki*; Ago, Tomohiro*; Hagura, Naoto*; Tsukahara, Takehiko*
Nuclear Instruments and Methods in Physics Research B, 542, p.206 - 213, 2023/09
Times Cited Count：1 Percentile：0.02(Instruments & Instrumentation)Hirao, Norie; Shimoyama, Iwao; Baba, Yuji; Izumi, Toshinori; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi
Bunseki Kagaku, 65(5), p.259 - 266, 2016/05
Times Cited Count：4 Percentile：14.21(Chemistry, Analytical)After the Fukushima nuclear plant accident, radiocesium was strongly fixed to clay minerals in the soil. Some dry methods with heating are being developed to remove radiocesium from the soil. In this work, we propose a new dry method that combines heat treatment in vacuum and molten salts to reduce the processing temperature in dry methods. Vermiculite saturated with non-radioactive Cs was heated in vacuum, and Cs contents in the vermiculite were compared before and after heating using X-ray photoelectron spectroscopy. Approximately 40% of cesium were removed by heating at 800
C for three minutes when only vermiculite was heated. Approximately 70% of cesium were removed by heating at 450C for three minutes when vermiculite was heated with NaCl/CaCl
mixed salts. Based on these results, this method is expected to reduce temperature and increase efficiency on dry methods for cesium removal from clay minerals.
Tsuji, Takuya; Matsumura, Daiju; Kobayashi, Toru; Suzuki, Shinichi; Yoshii, Kenji; Nishihata, Yasuo; Yaita, Tsuyoshi
Clay Science, 18(4), p.93 - 97, 2014/12
Yamada, Hirohisa*; Yokoyama, Shingo*; Watanabe, Yujiro*; Suzuki, Masaya*; Suzuki, Shinichi; Hatta, Tamao*
Nihon Ion Kokan Gakkai-Shi, 25(4), p.207 - 211, 2014/11
Ikeda, Takashi
Clay Science, 18(2), p.23 - 31, 2014/06
To clarify possible origins of irreversible adsorption exhibited by cesium on clay minerals, we performed FPMD simulations for vermiculite including water molecules along with Mg
, K
, and Cs in its interlayers. Our close examination on the structural and dynamical properties of interlayer water included together with the cations shows that Mg and Cs form respectively outer- and inner-sphere surface complexes in the interlayers, while K forms both types. The structure of electric double layers formed in the interlayers is found to depend significantly on the type of surface complexes of interlayer cations. The reorientational motions of HO are suggested to be enhanced by Cs in contrast to a minor influence of Mg and K. Our observed enhanced diffusion of interlayer HO along with their rapid reorientation indicates that Cs ions work as structure-breaking ions even in confined 2-dimensional interlayers.
Teraoka, Yuden; Iwai, Yutaro*; Okada, Ryuta; Yoshigoe, Akitaka
no journal, ,
The decontamination of 
Cs is urgently necessary, especially in Fukushima prefecture, to make volume reduction of radioactive waste. In order to develop volume reduction techniques, chemical bonding states of Cs adsorbed in clay minerals, e.g. vermiculite, has been studied by using synchrotron radiation X-ray photoemission spectroscopy (SR-XPS). In this presentation, an interpretation of data obtained by surface charge modulation using an electron flood gun during SR-XPS and chemical bonding states of Cs in the vermiculite are discussed. SR-XPS experiments were conducted at the surface chemistry experimental station of BL23SU in SPring-8. The natural vermiculite was processed to adsorb Cs so that the Cs concentration was 2.1 wt%. The synchrotron radiation energy was 1486.6 eV, identical with the Al-K
line. The Auger parameter of Cs of CsClO
was closest to that of Cs-contained vermiculite, implying Cs in the vermiculite may interact with oxygen. In order to confirm it, chemical shift of Cs-3d core level was measured and four components were found. The highest binding energy component only shifted by using an electron flood gun may be originated from hydration in weathered wide crevices. The other three components not shifted as well as K atoms originally-contained between phyllosilicate layers are corresponding to covalent interaction with O and Si atoms in narrow phyllosilicate interlayers.
Ikeda, Takashi
no journal, ,
no abstracts in English
Arai, Yoichi; Watanabe, So; Hasegawa, Kenta; Okamura, Nobuo; Watanabe, Masayuki; Takeda, Keisuke*; Fukumoto, Hiroki*; Ago, Tomohiro*; Hagura, Naoto*; Tsukahara, Takehiko*
no journal, ,
