Sorption Kinetics Considered as a Renormalized Diffusion Process

A theoretical study of the sorption kinetics is performed by using a new approach in which the adsorption-desorption process is considered as an extended diffusion process with a renormalized diffusion coefficient taking into account an interfacial potential barrier. This model allows us to describe the time dependence of the process by considering both the crossing of an interfacial potential barrier and the diffusion in the neighboring phase. This model leads us to write an expression for the surface concentration as a function of the time, in terms of the molecular activation energies of adsorption and desorption. The possibility of using this theoretical approach to interpret experimental data of dynamic interfacial tension during the absorption at liquid-liquid and liquid-gas interfaces is discussed.