Effect of polyvinyl alcohol adsorption on the mixed alumina–silica–titania suspension stability

The adsorption and electrokinetic properties as well as the stability of the AST71 suspension in the absence and presence of polyvinyl alcohol (PVA) were examined. AST71 is a mixed oxide of alumina, silica and titania. All measurements were carried out as a function of solution pH and the polymer molecular weight. The pooled result analysis showed that the PVA adsorption amount strongly depends on the solution pH. The higher solution pH value is, the more polymer macromolecules are adsorbed on the solid surface. This dependence is mainly associated with the PVA chain conformation. The adsorption of polyvinyl alcohol changes the stability of the AST71 suspension, but only in the solution of pH 9. Under these conditions the system without PVA is unstable, which is connected with the isoelectric point of the solid particles. In the presence of the polymer the electrosteric stabilization occurs.