First-principles Calculation Studies for Radioactive Cesium Adsorption to Clay Minerals

摘要

We perform first-principles calculations on cesium ion exchange in frayed edge sites of micaceous clay minerals in order to understand the chemical and physical characters of adsorbed cesium in top soil of Fukushima land area. The frayed edges are modeled by cutting the minimum unit in the muscovite crystal and simply expanding the layer distance according to the weathering scenario on the muscovite. We find that the frayed edge, i.e., a loosely expanded edge has a strong affinity for Cs by comparing the ion exchange energy before and after the exchange of the initially located K with Cs. The present calculations reveal that the strong affinity is ascribed to ion radius difference between K and Cs.