Colloidal stability in homo- and hetero-coagulation processes. Comparison between theoretical and experimental data

Abstract

In this work the colloidal stability of aqueous dispersions of uniform spherical cationic and anionic particles has been studied by turbidity measurements in homocoagulation and heterocoagulation processes. Two polymer colloids prepared by surfactant free emulsion polymerization were used throughout this work. Anionic and cationic latexes of similar surface charge densities, but with different particle sizes were selected. Once the adequate wavelength and the particle concentration into the cell were selected, the coagulation rate constants were estimated for the heterocoagulation and homocoagulation (cationic and anionic latexs) processes. By using the kinetic rate constants provided by the Muller and Smoluchowski equations, the Stern-Grahame model of the electric double layer, the total potential energy from the DLVO theory and some expressions from Reerink and Overbeek, we have compared the experimental and theoretical values of the homocoagulation and heterocoagulation rate constants, and also the diffuse potentials at the critical coagulation concentration.