KINETIC-EQUATIONS FOR TRANSFER-CONTROLLED ADSORPTION-KINETICS

The dynamic surface tensions of five systems showing transfer-controlled adsorption kinetics at high concentrations have been measured. The experimental results are used to investigate the kinetic equations for the adsorption processes, with the surface behaviour being not ideal or with an indifferent electrolyte added to an ionic surfactant. For non-ideal surface behaviour, the Langmuir kinetic equation is modified with surface activity coefficients based on regular solution theory, and the dynamic surface tensions are then well described. For the adsorption of an ionic surfactant with an indifferent electrolyte, a kinetic equation including the effect of the non-surface-active electrolyte is proposed and a parameter is described for relating the rate constants to concentrations. For ideal ionic systems the Langmuir-von Szyszkowski constants obtained from the kinetic surface tensions agree with those from equilibrium data. Moreover it is observed that for micellar systems in the region above the CMC the rate constant still increases up to a high concentration.