Stability of Clay Suspensions—Effect of pH and Polyethylenimine

The rate of destabilization of clay particles by pH control and by cationic polyethylenimine addition was measured by monitoring the change in light-transmittance and the formation of clay aggregates. The stability ratio W , expressed as the ratio of the maximum rate of destabilization to the measured rate, was correlated with the electrophoretic mobility of the clay particles. The maximum rate of destabilization corresponds to the conditions when the net charge of clay aggregates is close to zero. This would imply that in both the pH control and the polymer addition the dominant factors in destabilization are the electrostatic interactions.