Application of electrochemical impedance spectroscopy to analysis of solvent extraction mechanism of Mn(II)-8-hydroxyquinoline system

An electrochemical impedance spectroscopy (EIS) was used for the investigation of the solvent extraction of Mn(II) across water/1,2-dichloroethane interface. The electrochemical measurement allows one to obtain direct information concerning the charge transfer rate across the interface. The electrochemical impedance showed a capacitive semicircle and Warburg impedance on the Nyquist plane. The capacitive semicircle originates from the charge transfer resistance and the interfacial capacitance. The appearance of the Warburg impedance indicates the contribution of the diffusion process to the total charge transfer rate. A theoretical expression which presents the electrochemical impedance for Mn(II) solvent extraction was derived. The solvent extraction mechanism was discussed including some results in a simulation.