Changing the size of oil droplets dispersed in water without added surfactants

Abstract

Electrophoresis studies on pure hydrocarbon oil droplets, dispersed in water, have established that a significant charge is naturally developed on the droplets surface due to the spontaneous adsorption of hydroxyl ions. It has subsequently been pointed out that this charge should ensure the meta-stability of fine, micron-sized oil droplets dispersed in water. Further studies have demonstrated that such dispersions can be produced by the vigorous shaking of de-gassed mixtures of oil and water. De-gassing appears to enhance the dispersion process and the natural charging of the oil droplets ensures their meta-stability. Using this enhanced dispersion process, we have found that subsequent heating and cooling cycles, carried out over several minutes, can alter the average droplet size and the droplet size distribution, in some cases producing narrower distributions.