Foam flotation of clay particles using a bifunctional amine surfactant

Micheau, C.; Ueda, Yuki; Motokawa, Ryuhei; Bauduin, P.*; Girard, L.*; Diat, O.*

Langmuir, 39(31), p.10965 - 10977, 2023/07

https://doi.org/10.1021/acs.langmuir.3c01213

Computational science studies on radiocesium adsorption on clay minerals

Okumura, Masahiko

Chikyu Kagaku, 55(4), p.110 - 121, 2021/12

https://doi.org/10.14934/chikyukagaku.55.110

no abstracts in English

Mechanistic study on the removal of Cs from contaminated soil by rapid ion exchange in subcritical water

Fukuda, Tatsuya*; Takahashi, Ryo*; Hara, Takuhi*; Ohara, Koji*; Kato, Kazuo*; Matsumura, Daiju; Inaba, Yusuke*; Nakase, Masahiko*; Takeshita, Kenji*

Journal of Nuclear Science and Technology, 58(4), p.399 - 404, 2021/04

https://doi.org/10.1080/00223131.2020.1830866

Exploring the development of cesium removal processes via nanoscale chemical state analysis of cesium-containing clay minerals; Application of soft X-ray synchrotron radiation photoelectron microscopy to observe insulating materials

Yoshigoe, Akitaka

Hoshako Riyo No Tebiki, p.130 - 138, 2019/02

The educational book on next-generation synchrotron radiation usage is partially written. This book is being planned by several professors at Tohoku University. In this book, the contents which have already reported in our recent paper [Appl. Phys. Lett. 112 (2018) 021603.] are mainly written. The future perspective on photoemission electron microscopy using next generation synchrotron radiation and its possibility to analyze environmental samples and insulating functional materials are also described.

Nanoscale spatial analysis of clay minerals containing cesium by synchrotron radiation photoemission electron microscopy

Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.

Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01

https://doi.org/10.1063/1.5005799

A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M-edge region showed Cs to be present in a monocation state (Cs). Further pinpoint XAS measurements were also performed at the Fe L-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.

Localization of cesium on montmorillonite surface investigated by frequency modulation atomic force microscopy

Araki, Yuki*; Sato, Hisao*; Okumura, Masahiko; Onishi, Hiroshi*

Surface Science, 665, p.32 - 36, 2017/11

https://doi.org/10.1016/j.susc.2017.08.004

no abstracts in English

Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges

Okumura, Masahiko; Sassi, M.*; Rosso, K. M.*; Machida, Masahiko

AIP Advances (Internet), 7(5), p.055211_1 - 055211_9, 2017/05

https://doi.org/10.1063/1.4983213

no abstracts in English

Molecular simulation of cesium adsorption at the basal surface of phyllosilicate minerals

Kerisit, S.*; Okumura, Masahiko; Rosso, K. M.*; Machida, Masahiko

Clays and Clay Minerals, 64(4), p.389 - 400, 2016/08

https://doi.org/10.1346/CCMN.2016.0640405

no abstracts in English

First-principles calculation studies on cesium in environmental situations; Hydration structures and adsorption on clay minerals

Machida, Masahiko; Okumura, Masahiko; Nakamura, Hiroki; Sakuramoto, Kazuhiro*

Proceedings of Joint International Conference on Mathematics and Computation, Supercomputing in Nuclear Applications and the Monte Carlo Method (M&C + SNA + MC 2015) (CD-ROM), 12 Pages, 2015/04

In order to clarify physicochemical behaviors of radioactive Cs released into environment from the Fukushima Daiichi Nuclear Power Plants, we study on two issues, i.e., hydration structures of Cs and its adsorption on a specific edge in a clay particle (mica) by employing first principles calculations. In this paper, firstly, we report on hydration structures of Cs by using Born-Oppenheimer first-principles molecular dynamics. Our striking finding in the hydration structures is that Cs has no clear second hydration shell in contrast to any other alkali cations. Secondly, we construct a model of the Frayed Edge Site and confirm that the model actually becomes selective for Cs when expanding the interlayer distance from that of the original crystal structure through the calculation of the ion-exchange energy.

Cs adsorption mechanism on clay minerals based on material sciences using synchrotron radiation and first principle calculation

Yaita, Tsuyoshi; Kobayashi, Toru; Ikeda, Takashi; Matsumura, Daiju; Machida, Masahiko; Okumura, Masahiko; Nakamura, Hiroki

Hoshako, 27(6), p.315 - 322, 2014/11

no abstracts in English