The cesium absorption behavior of vermiculite was studied to see how it performs for the clean up process of polluted water including radioactive cesium produced by decontamination of houses, etc. It is possible to expand the surface area of vermiculite by means of heat-treatment, but dehydration of the interlayer water and destruction of the layer structure causes that the adsorption ability decreases or is lost. Therefore, our attention is onto the particle size of the natural raw vermiculite. Based on an ion-exchange experiment using vermiculite, we found that adsorption ability doesn't depend on the surface area up to the certain size of vermiculite grain. Lower flow rates were required to obtain an acceptable uptake by the column method, but this issue was overcome by using a combine column that contains the same amount of vermiculite as a single column.

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 Advanced Liquid Processing System (ALPS) is a water treatment facility for decontaminating high-level radioactive water from the Fukushima Daiichi Nuclear Power Plant. The radioactivity of ⁹⁰Sr is so high that the development of selective adsorbents for Sr²⁺ ions is one of the most important issues in the treatment of contaminated water. The authors focused on layered potassium titanate, which has excellent Sr²⁺ ion-exchange capability, and then developed granular Sr²⁺ adsorbent “Moleculite SR” manufactured with potassium bititanate. The granulating process is important for the operation an adsorption system flowing contaminated water into a column. This paper addresses the following issues: (1) Heat resistance of potassium bititanate, (2) the Sr²⁺ adsorption properties of Moleculite SR in an aqueous solution with high salinity, (3) the Irradiation resistance of Moleculite SR.

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