On the adsorption kinetics of octanoic acid at the mercury electrolyte interface

The adsorption kinetics of octanoic acid at the mercury/electrolyte interfa ce was investigated by means of capacity-time transients. For low concentra tions of octanoic acid and for the short-term region, the transients can be theoretically well described with a diffusion-controlled adsorption proces s according to the Delahay-Trachtenberg law. The long-term transients for h igher concentrations of octanoic acid exhibit an increase of the capacity w ith time, which can be modeled with an adsorption-controlled replacement of a condensed adsorption state by a hemimicelle adsorption state. Criteria a re derived for which an increase of the double-layer capacity with time can be expected.