Cation sorption at the muscovite-water interface using X-ray reflectivity

摘要

High-resolution in-situ X-ray reflectivity measurements were used to characterize the sorption of K, Cs, Ca, and Ba from chloride solutions and Zn from chloride, nitrate, and trifluorosulfonate (triflate) solutions onto the basal surface of muscovite. X-ray reflectivity data were collected through the specular reflection condition and converted to electron-density profiles perpendicular to the interface by applying atomistic structural models that included surface relaxation, sorbate concentration and position, water structure, and surface roughness. Cations were attached to the basal surface dominantly in the first adsorbed layer, which has the highest electron density of the solution phase. All derived heights imply that no separate water layer exists between the sorbates and mineral surface. Water layering above the sorbed cation layer and minimal relaxation of the bulk muscovite were observed.