Quantitative Elucidation of Cs Adsorption Sites in Clays: Toward Sophisticated Decontamination of Radioactive Cs

• Published in: Journal of physical chemistry. C Vol. 120; no. 2; pp. 1270 - 1274
• Main Authors: Sato, K, Fujimoto, K, Dai, W, Hunger, M
• Format: Journal Article
• Language: English
• Published: American Chemical Society 21.01.2016
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b09350

For successful 137Cs decontamination from the soil environment, Cs adsorption sites for a saponite (i.e., a silicate clay of highly complex soil material) are highlighted based on the results of Fourier transform infrared (FT-IR) spectroscopy, 133Cs magic-angle-spinning nuclear magnetic resonance (MAS NMR), radiocesium interception potential (RIP), and a conventional elution experiment. Heavily adhesive Cs adsorption was found to originate from Cs chemisorption at nanosheet edges and Cs confinement in wedge-shaped parts available in the interior of local molecular structures, in which one- and two-nanosheets are inserted into the interlayer spaces. The multidisciplinary approach covering physical, chemical, and geochemical techniques successfully determines the concentrations of Cs-adsorption-associated nanosheet surfaces, nanosheet edges, wedge-shaped parts, and oncoming hexagonal cavities to be 322, 238, 9 × 10–2, and 207 mmol kg–1, respectively. Radioactive 137Cs that is not cleaned up after decontamination work could occur at nanosheet edges and wedge-shaped parts of more than 30%.