Advancing understanding of biotite weathering reactions; XAFS and ab initio simulation insights

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

Chemical reactions such as adsorption, precipitation, and redox play an important role in the environmental fate of elements, and understanding the chemical state and local structure is necessary to understand changes in their behavior. Although the X-ray absorption near edge structure (XANES) method has the advantage of high element selectivity, its resolution and analytical methods have some issues. To address these issues, this study utilizes high-energy-resolution fluorescence detection (HERFD)-XANES measurements and ab initio calculations. Analysis of artificially weathered biotite samples revealed systematic oxidation of Fe(II) to Fe(III) due to weathering. In addition, detailed microstructures of the weathered biotite with cesium adsorption were also obtained.