Polar‐Screen Theory for the Deflocculation of Suspensions

Deflocculation of suspensions results from the formation of surface charges on particles. The strongest charges are obtained by the hydrogen bonding of polar ions or molecules on particle surfaces. Measurements were made of the deflocculation of alumina in both polar and non‐polar liquids using various acids, bases, and electrolytes. The pH of suspensions was found to be temperature‐dependent, the pH decreasing with increasing temperature. The results of these experiments are not compatible with the double‐layer theory for the deflocculation of suspensions. The polar‐screen theory explaining deflocculation by the hydrogen bonding of polar ions or molecules to electronegative surfaces is presented. The polar ions or molecules provide the surfaces with a charged screen. Predictions are made on the basis of this theory and are experimentally verified.