Zeta potential-viscosity relationship in kaolinite slurry in the presence of dispersants

Abstract

Kaolinite is a widely used additive for industrial applications. Hence, the properties of kaolinite affect the quality of the final materials. The fact that kaolinite is a heterogeneous mineral with dual charges has to be taken into account. In this study, the zeta potentials and the apparent viscosities of kaolinite suspensions in water in the presence of three dispersants; sodium silicate, sodium tripolyphosphate and sodium-polyacrylate at pH values of 4, 7 and 10 were determined. Diagrams of zeta potentials (ZPs) and viscosity as a function of dispersant concentration all show minima. The concentrations at which minima of these two properties appear do not coincide, except for those mineral dispersants at high pH values. The results are explained in terms of the spatial distribution of charges on basal and edge surfaces of kaolinite plates in acidic, neutral, and basic media.