On Zeta Potential of Kaolinite Suspension under the Alkaline Condition

In this paper we examined in detail how the mobility of kaolintite changes with salt concen tration, and how Na-kaolinite water system flocculates as salt is added at pH10. We also studied how dispersion-flocculation depends on zeta potential by comparing the results of mobility with limited viscosity, a useful way to estimate particle s Our conclusions are as follows: 1) Because the mobility of kaolinite increases with salt concentration within the range of flocculation, experimental results don't conform to the theory of diffuse double layer.These phenomena occur because of the formation of flock, when accompanied by an increase in salt concentration. 2) In dispersion state, the relation between zeta potential and salt concentration conforms to Gouy & Chapman's theory of diffuse double layer under constant surface potential. Furthermore, the surface potential, 56mV, and the position of the slipping plane, 2.3nm, were obtained about Iriki kaoline from analysis of the experimental data. 3) It is necessary to clarify the particle state of a clay-water system when measuring the zeta potential, because mobility is heavily dependent on the dispersion-flocculation of the clay-water system.