SORPTION KINETICS AT LIQUID-LIQUID INTERFACES WITH THE SURFACE-ACTIVECOMPONENT SOLUBLE IN BOTH PHASES

A theoretical study on the sorption kinetics at liquid-liquid interfac es of surfactant component soluble in both phases is presented here. T he diffusion process in bulk phases is considered as well as the prese nce of an interfacial potential barrier to adsorption and desorption. In the present paper, a generalization of a recent study on the sorpti on kinetics at a fluid interface with a surface-active component solub le in only one phase [F. Ravera et al., J. Colloid Interface Sci. 156, 109 1993)] is given. The new approach consists of writing a renormali zed diffusion equation, equivalent to the kinetic sorption equation, b y introducing renormalized diffusion coefficients and boundary conditi ons suitable for the bulk concentrations. The treatment leads to a rel ationship between the surface excess concentration and tile time, in t erms of the interfacial potential barriers of adsorption and desorptio n. (C) 1994 Academic Press. Inc.