INTERACTIONS OF COLLOIDAL DISPERSIONS WITH ELECTROLYTES

A classification of counterions based on the nature of their interactions with lyophobic sols is offered. The influence of adsorption on the coagulation ability of counterions, particularly of hydrolyzed metal ions, is discussed. Log molar salt concentration-pH domain curves are presented for Ludox AM colloidal silica (0.2 gram per 100 cc.) and the ions Na+ Ca2+ La3+, and AL3+. These are compared with the corresponding coagulation domains of two silver halide sols; the differences are attributed to hydration and the effect of pH on the silica surface. Conditions are outlined under which the critical coagulation concentration depends primarily on the charge of the counterion. © 1969, American Chemical Society. All rights reserved.