Inhibition of the electrode reduction of an adsorbed species by the competitive adsorption of a surfactant

An experimental study was carried out on the inhibitory effect of a surfactant on the electrode reduction of cefazolin. The reduction potential was found to shift to more negative values with an increase in the surfactant concentration, while the transfer coefficient of the process remained unaltered. The inhibitory effect is accounted for on the basis of a model that takes account of the competitive adsorption of the two substances only. The variation of the rate constant of the process with the logarithm of the surfactant concentration allowed calculation of the ratio between the number of solvent molecules displaced by the reactant and the surfactant, respectively.