title: Mesoscopic structures of vermiculite and weathered biotite clays in suspension with and without cesium ions.
abstract: The effect of cesium (Cs) adsorption on the mesoscopic structure of the clay minerals vermiculite and weathered biotite (WB) in suspensions was elucidated by small-angle X-ray scattering (SAXS). The clay minerals form multilayered structures, and the Cs cations (Cs(+)) are strongly adsorbed in the interlayer space of the soil clays, in particular vermiculite and WB. SAXS was used to monitor the relationship between Cs(+) adsorption at the clay interlayers and the structural changes at length scales from 1 to 1000 Å. The variation in the distance between the neighboring clay sheets and the spatial arrangement of the clay sheets with and without Cs(+) were clarified. Our quantitative analyses revealed that the number of stacked layers of pure vermiculite was decreased by Cs(+) addition, whereas that of WB increased. Moreover, the average distance between the neighboring layers of vermiculite in suspension was larger than that of WB, which reflects the different conditions of Cs(+) intercalation. These findings provide fundamental insights that are important for predicting the environmental fate of radioactive Cs in contaminated regions and for developing methods for extracting Cs from soil.
authors.affiliation: Actinide Coordination Chemistry Group, Quantum Beam Science Center (QuBS), Japan Atomic Energy Agency (JAEA) , Tokai, Ibaraki 319-1195, Japan.
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Motokawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
authors.forename: Shingo
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ogawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yaita