Abstract: Talc，a kind of phyllosilicate， will form two kinds of surfaces with distinct properties when dissociated. Different surfaces exhibit different wettability and charge density. The surface properties of the basal and the edge surfaces of natural talc were investigated by direct surface force measurements using atomic force microscope （AFM） and classical DLVO （Derjaguin-Landau-Verwey-Overbeek） theory. The potential values of the silicon nitride （Si₃N₄） were calculated determine at various pHs using AFM. The interaction forces between the AFM tip （Si₃N₄） and basal or edge surface of talc which is consistent with roughness requirements were measured in 10 mmol/L KCl solutions at various pHs. The force profiles were well-fitted with classical DLVO theory to determine the surface potentials of the basal and the edge surfaces of talc. The surface potentials of basal surface exhibits negative invariably in the range of pH 3.5~9.5. The edge surface becomes more negative with increasing pH and the point of zero charge （PZC） of the edge surface was determined around pH 7.6. The fitting curve of the force between the calculated talc surface potential and silicon nitride is compared with the actual measured force. The calculated value is basically consistent with the measured value and the fitting degree is high.

Key words:  Talc, Anisotropic, Surfaces properties, Adsorption