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 Dola pix 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 viscosi ty changes were monitored. The neutralisation of the surface charge on the particles occurs because of the formation of coordinative bonds between mag nesium ions and carboxylic groups of the dispersant molecules, which is ref lected in the destabilisation of the suspension. A thin and rigid neutral l ayer on the surface of the particles is formed which prevents the close con tact between particles. As a consequence, weak flocculation of the suspensi on takes place and the resulting short-range repulsive potential was confir med with force measurements. (C) 2001 Elsevier Science Ltd. All rights rese rved.