Extended X-Ray Absorption Fine Structure Study of Cobalt-Exchanged Sepiolite
Yoshiaki Fukushima, Tokuhiko Okamoto, 1985. "Extended X-Ray Absorption Fine Structure Study of Cobalt-Exchanged Sepiolite", Proceedings of the International Clay Conference Denver, 1985, Leonard G. Schultz, H. van Olphen, Frederick A. Mumpton
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Natural sepiolite and synthetic loughlinite, prepared from sepiolite by treatment with an aqueous solution of NaOH, were immersed in a 1.0 N aqueous solution of Co(NO3)2 for about 30 hr at 20°C. Local structure around the Co ions was studied by X-ray powder diffraction and two types of X-ray absorption experiments—extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES). The results can be explained well by a model in which Co ions substituted for Mg or Na ions in octahedral sites in the sepiolite or the synthetic loughlinite.
The d(110) values and Mg, Na, and Co contents of the sepiolite and synthetic loughlinite treated with aqueous NaOH and Co(N03)2 solutions support this substitution. In synthetic loughlinite, about 15% of octahedral sites were substituted by Co after a 30-hr treatment, whereas only about 4% of the sites in the natural sepiolite were substituted.
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Proceedings of the International Clay Conference Denver, 1985
The papers included in this proceedings volume are representative of the research on clays being conducted in all parts of the world at the time of publication. Many of the subjects treated are controversial, and although some ideas expressed may not necessarily represent the views of the editors, the referees, or the publisher, they deserve to be brought to the attention of the international clay community.