The changes in capacitance, interfacial tension and optical properties produced by a monolayer of a amphiphilic compound are the most important phenomena reported [1] concerning adsorption processes at liquid-liquid interfaces. Few evidences of adsorption-desorption process involving charge transfer in this kind of systems have been published [2].

The present research shows the adsorption of phenosafranine (FS⁺) at the water-1,2 dixhloroethane interface using cyclic voltammetry and potential pulses followed by a linear potential sweep.

During the positive potential sweep a diffusionally controlled reversible process is observed. On the other hand in the neghative potential sweep the appearance of a sharp peak is indicative of a non-diffusional process. This fact and the linear behavior of the peak current with potential sweep rate are the most important evidences of an adsorption-desorption process. Moreover an increase of the interfacial coverage produces a shift of the negative peak potential.

The experimental curves were fitted with the Frumkin isotherm wich allowed the interaction parameter to be calculated.

These evidences together with the dependence of the adsorption process with the switching potential and the nature of the base electrolyte have led us to propose a global transfer mechanism.

1.  T. Kakiuchi, M. Nakanishi, M. Senda. Bull. Chem. Soc. Jap. 61 (1988) 1845.

2. A. Azcurra, L. Yudi, A. Baruzzi. J. Electroanal. Chem. 461 (1999) 194.