Anisotropic surface features of selected phyllosilicates

The phyllosilicate minerals are very important in geology, agriculture, and a wide range of industries. It has been known that almost all the processes in mineral processing are significantly influenced by the surface properties of the phyllosilicates. Therefore, the objective of this research is to investigate the anisotropic surface properties of selected phyllosilicates using both experimental and theoretical methods. A new technique based on atomic force microscopy (AFM) was developed to determine the anisotropic wetting characteristics of kaolinite basal surfaces. The hydrophobicity was determined by the magnitude of the hydrophobic attraction force between a hydrophobic diamond-like-carbon (DLC) AFM tip and the kaolinite basal surfaces. The results demonstrate that the kaolinite silica face has a moderate degree of hydrophobicity, whereas the kaolinite alumina face is hydrophilic. The hydrophobicity of the kaolinite silica face is found to be weaker than the talc basal surface, which may be due to the presence of isomorphous substitutions. Using molecular dynamics simulation (MDS), it is noted that the wetting characteristics and the interfacial water structure of the silica tetrahedral surface of phyllosilicates are greatly affected by the isomorphous lattice substitution. In addition, the surface charging behaviors of chlorite basal plane surfaces and the edge surface were established as a function of pH. It is expected that the findings from this dissertation research will provide a basis for understanding the behavior of layered silicate particles in flotation systems, leaching systems, and tailing disposal systems.