Voltammetric elucidation of the process of self-sustained potential oscillation observed with a liquid membrane system composed of water containing cetyltrimethylammonium chloride vertical bar nitrobenzene containing picric acid vertical bar pure water

The process of the self-sustained oscillation of the membrane potential was elucidated referring to voltammograms for ion transfer at two interfaces e xisting in the membrane system. The membrane system investigated was compos ed of one aqueous solution, W1, containing cetyltrimethylammonium chloride, CITA(+)Cl(-), a nitrobenzene liquid membrane (LM), containing picric acid and another aqueous solution, W2, in the absence of any salt. The oscillati on of the membrane potential was attributed to that of the potential differ ence at the W2 \ LM interface, E-W2 \ LM, and E-W2 \ LM was demonstrated to oscillate between that determined mainly by the transfer of H+ and Pic(-) from LM to W2, and that determined by the transfer of H+ and Cl- from LM to W2. Fundamental features such as the membrane potential during the inducti on time and the amplitude of the oscillation predicted based on the process proposed in the present work agreed quantitatively with those observed wit h the membrane system. (C) 2001 Elsevier Science B.V. All rights reserved.