The Adsorption of Sulphonate on Fluorite Single Crystals as Examined by in-situ FT-IR Internal Reflectance Spectroscopy

The adsorption densities of dioctyl sodium sulphosuccinate (AOT) at the surface of a fluorite single crystal were calculated from in situ FT-IR internal reflection spectroscopic data. The results were analyzed according to the modified Frumkin isotherm in order to evaluate the lateral interaction coefficient, a, and the adsorption free energy change, ΔGθ0. The adsorption kinetics of AOT at a fluorite internal reflection element (IRE) were studied. In addition, by monitoring the –CH2 adsorption band using polarized light, it was possible to investigate the orientation of the adsorbed species on the fluorite IRE surface.