LIGHT-SCATTERING STUDY OF SOLUBILIZATION OF EMULSION DROPLETS BY NONIONIC SURFACTANT SOLUTIONS

Light scattering (dynamic and static) and turbidity measurements were used to monitor the time dependence of the concentration and size of n -hexadecane emulsion droplets (initial diameter approximate to 0.43mm) dispersed in non-ionic surfactant solutions (2 wt.% polyoxyethylene s orbitan monolaurate). The concentration of droplets decreased with tim e as n-hexadecane molecules were solubilized by surfactant micelles, b ut the droplet size distribution remained constant. The results are co nsistent with a mechanism in which oil molecules are exchanged between emulsion droplets and surfactant micelles at the oil/water interface. The measured solubilization kinetics appear to be dominated by interf acial transport processes, and can be predicted by an interfacial mass transfer coefficient of 9.7 x 10(-6) cm min(-1).