Effect of ethanol on the solubilization of hydrocarbon emulsion droplets in nonionic surfactant micelles

Light scattering was used to study the effects of ethanol on the mass transport of hydrocarbon molecules from emulsion droplets to nonionic surfactant micelles. n-Hexadecane oil-in-water emulsions (10 wt%) with a mean droplet diameter of 0.97 μm stabilized by 2 wt% polyoxyethylene sorbitan monolaurate, were prepared. These emulsions were diluted to 0.04 wt% n-hexadecane using a series of aqueous solutions containing different concentrations of ethanol (0 to 20 wt%) and polyoxyethylene sorbitan monolaurate (0 or 2 wt%). The time dependence of the droplet concentration and size distribution were monitored at 30°C using light scattering. The molecular flux of the solubilization process increased with increasing ethanol concentration, but the maximum amount of oil solubilized per unit amount of surfactant was independent of ethanol concentration. The data are interpreted in terms of the molecular processes that occur during solubilization.