LOCAL STRUCTURAL INFORMATION FROM EXAFS ANALYSES AND ADSORPTION MODE OF STRONTIUM ON SMECTITE

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概要

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• To elucidate the adsorption sites and behavior of Sr atoms on smectite, EXAFS spectroscopy was performed at the Spring-8 using air-dried and wet-paste samples of Sr-adsorbed bentonite adjusted to pH 4.7 and 9.6. EXAFS analyses were conducted for the two-oxygen shell fit using a crystalline SrSO_4 as a reference compound. The first-neighbor shells consisted of 5.5 O atoms of water molecules at a distance of 2.58Å in the air-dried sample and 7.0 O at 2.60Å in the wet sample. The second shells consisted of 2.6 O atoms at a distance of 2.77Å and 2.5 O at 2.81Å for the air-dried and wet samples, respectively. Only the Debye-Waller factors of the second shells were affected by the pH, resulting to be smaller at pH 4.7 than those observed at pH 9.6. It is concluded from the EXAFS results that Sr atoms are attracted stronger to the 2:1 sheets of smectite in the air-dried compacted samples than in the wet-paste samples because of the smaller Debye-Waller factors in the air-dried compacted samples. The Sr atoms hovered on a triangle of the oxygen hexagonal cavity on the flat surface of 2:1 sheets and resided on the broken face of the octahedral sheets at the edge surface. In addition, they behaved as hydrated ions and formed incomplete outer-sphere complexes at high water content; however, they formed incomplete inner-sphere-like complexes together with oxygen atoms of the 2:1 sheets in the air-dried samples. The Sr atoms also played a role combining two sheets of the 2:1 layer of smectite in forming the edge-to-edge and edge-to-face associations.

• 日本粘土学会の論文

著者

• KAWAMURA KATSUYUKI

  Tokyo Institute of Technology, Division of Earth and Planetary Science

• Nakano Masashi

  Univ. Tokyo Tokyo Jpn

• NAKANO Masashi

  Research Institute of Soil Science and Technology

• Emura Shuichi

  Osaka University Institute Of Scientific And Industrial Research

• Kawamura Katsuyuki

  Tokyo Inst. Technol. Tokyo Jpn

関連論文

• MODELING ESTIMATION OF MICROBIAL DECOMPOSITION OF CALCIUM SILICATE HYDRATE AND CONCRETE BIODEGRADATION
• EXAFS Studies about the Sorption of Cadmium Ions on Montmorillonite
• LOCAL STRUCTURAL INFORMATION FROM EXAFS ANALYSES AND ADSORPTION MODE OF STRONTIUM ON SMECTITE
• Adsorption Sites of Cs on Smectite by EXAFS Analyses and Molecular Dynamics Simulations(Characterization of Clays,Proceedings of the 13^ International Clay Conference)
• The Viscosity of Suspensions of Bentonite(Clays in Industry,Proceedings of the 13^ International Clay Conference)

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