LAUSR

Smooth basal surfaces of illite were prepared successfully, and the interaction forces between a Si3N4 tip and illite basal surface with various concentration divalent cations in 10 mM KCl solution at pH 8.0 and 10.8 were measured using an atomic force microscope (AFM). The influence of divalent cation concentration on the interaction forces were investigated, and the surface potentials of the basal surfaces in varying concentration divalent cations solutions were determined by fitting the interaction forces with the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. With increasing CaII or MgII concentration, the surface potentials became less negative in pH 8.0 solution, while the surface potentials reversed from negative to positive after adding 1.0 mM or more divalent cations in pH 10.8 solution. Electrostatic interaction and specific adsorption were the major contributors to the interaction between divalent cations and illite basal surface in solutions at pH 8.0 and 10.8, respectively. CaII an...