The primary electroviscous effect in ageing AgI sols: Effect of increasing concentrations of counter ions of different valencies

Abstract

The electroviscous effect in negatively charged AgI sol has been measured in presence of uni-, bi-, and trivalent cations at different concentrations, for a constant low volume fraction of the suspended solid particles. The I − ion activity of the sol (and also the particle size) gradually increased due to ageing effect during the entire course of study over a period of several months, but remained effectively constant during each course of study (over a few days) with any particular counterion. The potentials were simultaneously measured electrophoretically at identical electrolyte and I − ion concentrations. The electrical (double layer) contribution to the viscosity of the sol was calculated for various values of q o for each electrolyte. A close correspondence has been found in each case with the potential results.