J. ElectroanaL Chem., 149 (1983) 179-183 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands 179 INVESTIGATION OF THE ION TRANSFER ACROSS THE WATER-NITROBENZENE INTERFACE BY ac CYCLIC VOLTAMMETRY B. HUNDHAMMER *, THEODROS SOLOMON and HAILEMICHAEL ALEMU Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa (Ethiopia) (Received 10th November 1982) ABSTRACT The technique of ac cyclic voltammetry has been applied to the study of ion transfer across the water-nitrobenzene interface. The reversibility of the ion transfer, as well as precise A'~I/2 values, can easily be determined using this method, as demonstrated for the ions CIO4, Cs ÷, and NOr. INTRODUCTION Ion transfer across the interface of immiscible electrolyte solutions has been investigated by several electrochemical techniques such as chronopotentiometry [1-3,6], cyclic voltammetry and polarography [4-11]. The structure of the water-nitrobenzene interface has been studied by Samec et al [12] employing the ac impedance technique but without IR compensation. Bond et al. [ 13,14] have shown that ac cyclic voltammetry at solid electrodes links the advantages of cyclic voltammetry with those of the ac techniques. It retains the diagnostic utility of conventional cyclic voltammetry combined with an improved response function that permits quantitative informations about the charge-transfer reactions. Since the electrochemical response of the interface between two immisci- ble electrolyte solutions is similar to that of a metal-electrolyte solution electrode interface ac cyclic voltammetry ought to be a useful additional method for the investigation of the ion transfer across the interface of two immiscible electrolyte solutions. The theoretical treatment of ac cyclic voltammetry is based on the independence and significant difference of the ac and dc time scales. The conventional dc cyclic voltammetry yields information about mean interfacial concentrations which are then used, in ac cyclic voltammetry, for determining the faradaic impedance through measurements of the amplitude and phase angle of the current. * Permanent address: Technische Hochschule "C. Schorlemmer", Leuna-Merseburg, Sektion Chemie, 4200 Merseburg, G.D.R. 0022-0728/83/$03.00 © 1983 Elsevier Sequoia S.A.