Ge isotopic equilibrium fractionation between Ge-containing ferrihydrite and the aqueous solution

Abstract

Since Ge has a strong affinity for Fe, iron oxyhydroxide is assumed to be one of the potential “missing sinks” of Ge. Ferrihydrite is commonly found in soil and sediments and has a strong affinity for heavy metals. In this study, the first principle method based on density functional theory was used to optimize the geometry of Ge-containing ferrihydrites and H4GeO4 aqueous solution molecular clusters at B3LYP/6-311G(d) level. Solvation effects are treated by “water-droplet” method. Finally, at 298.15 K we obtained the Ge isotopic equilibrium fractionation between Ge-containing ferrihydrites and H4GeO4 aqueous solution, Δ74/70Geferrihydrite-aq= -1.97‰. It enriches the document of Ge isotopic fractionation and helps to assist the study of Ge global cycle.