Systematic understanding of adsorption structures of cations on clay minerals; Complementary use of EXAFS experiments and first-principles calculations

Yamaguchi, Akiko  ; Takahashi, Yoshio*; Okumura, Masahiko   

Clay minerals control the environmental behavior of various elements because they exist widely in the surface of the Earth and adsorb many cations. Since the adsorption strength of clay minerals varies depending on the adsorption structure at the molecular level, it is important to systematically understand what determines the adsorption structure at the molecular level. In this study, we systematically compared many cations using extended X-ray absorption fine structure (EXAFS) measurements and first principles simulations. The results showed that not only the hydration enthalpy, which has been considered important in the conventional understanding, but also the size of the adsorbed ions is important.