Abstract:Quantum chemical simulation calculation shows that kaolinite is cleaved to produce (001) and (001^-) basal planes. (001) plane is dominant by ［SiO₄］ tetrahedral, which interacted easily with hydrogen ion or other positive ions by electrostatic forces or hydrogen bonding. (001^-) plane is dominant by ［AlO₂(OH)₄］, which interacted easily with high negativity group such as -O-, -N-, F- etc. The apparent zeta potential and surface points of zero charge(PZC) are different for hard and soft kaolinites depending on their crystallinity index (HI). The self-aggregation between edge and basal plane due to the electrostatic interactions may occur at acidic media. The dispersion of kaolinite particles at alkaline media may be attributed to the electrostatic repulsion between basal planes and/or edges. The aggregation or dispersion behavior is revealed by scan electron microscope and the transmittance measurements for the suspension of kaolinite particles.

Key words: kaolinite; cleavage planes; electrokinetics; self-aggregation; dispersion