ADSORPTION-KINETICS WITH TIME-DELAY

A theory of adsorption kinetics of solutes onto a solid surface from the solution phase is proposed in which a time delay is introduced into the solute concentration on the surface. Equations governing the adsorption kinetics are similar to those for membrane transport with time delay (Ohshima and Kondo, Biophys. Chem. (1989) 33: 303). It is found that introduction of time delay-tau causes, under certain conditions, overshoot or oscillation in the solute concentrations, both in the solution phase and on the surface. The criterion for oscillation depends on the scaled delay time-alpha-tau, the ratio of the possible maximum amount of solutes adsorbed on the surface to the total solute amount R, and the scaled binding constant K. When the number of the binding sites is small, the criterion for oscillation is expressed as gamma > exp (- 1), where gamma = (alpha-tau/K) exp (alpha-tau).