Influence of Temperature on Stability of Electrostatically Stabilized Alumina Suspensions

Pure electrostatically stabilized aqueous alumina suspensions were prepared at various solid loadings in order to study the influence of temperature on the surface charge properties and rheology. Surface charge density at various temperatures was measured through potentiometric titration, and the analysis of the potentiometric data was accomplished using the constant capacitance surface model. Calculations of the pair-wise interaction potential between charged colloidal spheres dispersed in water were then carried out using conventional DLVO theory and a software package Stabil45, taking into account the temperature dependence of surface charge density and dielectric constant. The results showed that increasing temperature leads to a gradual diminution of alumina surface ionization, dielectric constant, and a total energy barrier for coagulation. The enhancement of the coagulation rate with increasing temperature leads to a gradual increase of both relative apparent viscosity and thixotropy. Copyright 2000 Academic Press.