VOLTAMMETRIC STUDY ON THE OSCILLATION OF THE POTENTIAL DIFFERENCE AT A LIQUID LIQUID OR LIQUID MEMBRANE INTERFACE ACCOMPANIED BY ION TRANSFER

The oscillations of potential difference at the interface between an aqueous solution containing MgSO4 and an organic solution containing dilute Cs+ or tetramethylammonium ion (TMA+) and fairly concentrated tetrapentylammonium tetraphenylborate (TPenA+· TPhB-) were investigated by forcing the transfer of Cs+ or TMA+ at the interface through an applied current. The organic solvents employed were nitrobenzene, 1,2-dichloroethane and o-nitroanisole. The necessary conditions for the oscillation were confirmed to be identical to those for the appearance of the maximum in the voltammogram for the ion transfer at the interface. By referring to the voltammogram and the drop tune-potential curve and taking into account the ion-pair formation equilibrium in the organic, such characteristics of the oscillation as the amplitude, the pulse width, the period and the range of applied current were elucidated, and a mechanism for the oscillation is proposed. The result at the aqueous/organic interface is connected to the oscillation of the potential at a liquid membrane. © 1990.