Simple Experiments to Emphasize the Main Characteristics of the Coagulation of Silica Hydrosols by Alkaline Cations: Application to the Analysis of the Model of Colic et al.
There is no consensus about the peculiar stability-coagulation behavior of silica hydrosols, in the presence of alkaline cations. Interparticle bridging or van der Waals forces prevented by steric barriers constitute the two classes of explanations. There is no agreement either on the experimental data, especially at high pH. Simple and fast experiments are proposed here, in order to clarify what must be the basis of any theory. The recent proposition of Colic et al., that involves steric barriers provided by adsorbed cations, is analyzed and shown to be unable to explain the complex behavior of silica hydrosols. Copyright 1999 Academic Press.
Depasse
J
Institut de Pharmacie CP206/4, Université Libre de Bruxelles, Bd du Triomphe, Brussels, 1050, Belgium