Surface Characteristics of Kaolinite and Other Selected Two Layer Silicate Minerals

The electrokinetic features and interfacial water structure, as revealed from molecular dynamics simulations (MDS) are considered with respect to the anisotropic features of selected two layer silicate minerals. Planar structures of kaolinite and antigorite are compared to the, compositionally equivalent, tubular structures of halloysite and chrysotile with respect to the pH dependency of zeta potential as determined from the electrophoretic mobility measurements. The importance of the atomic mismatch between the tetrahedral and octahedral sheets in a particular bilayer is discussed in order to explain the electrokinetic behaviour of these two layer silicate minerals. Interfacial water structure from MDS suggests that the silica tetrahedral surface is not wetted by water. In the case of planar silicates structural imperfections are considered to explain wetting characteristics. The possibility of polarity reversal (domain inversion) within a tetrahedral/octahedral layer and an out‐of‐order layer (inserted layer) within the tetrahedral/octahedral stack are considered in order to explain electrokinetic behaviour and wetting characteristics.