Short-range repulsive potential developed by the addition of Mg(II) ions to aqueous alumina slurries

The effect of magnesium acetate additions on the interparticle potential of diluted well-dispersed aqueous alumina suspensions, prepared with the Dolapix CE64 dispersant at inherent pH, and the rheological properties of these suspensions, have been studied. In order to destabilise these suspensions a 0.5 M aqueous magnesium acetate solution was added and the pH and viscosity changes were monitored. The neutralisation of the surface charge on the particles occurs because of the formation of coordinative bonds between magnesium ions and carboxylic groups of the dispersant molecules, which is reflected in the destabilisation of the suspension. A thin and rigid neutral layer on the surface of the particles is formed which prevents the close contact between particles. As a consequence, weak flocculation of the suspension takes place and the resulting short-range repulsive potential was confirmed with force measurements.