Ion transfer kinetics at the micro-interface between two immiscible electrolyte solutions investigated by electrochemical impedance spectroscopy and steady-state voltammetry

The kinetics of tetraethylammonium (TEA+) ion transfer across the water/1,2-dichloroethane interface was studied using electrochemical impedance spectroscopy and steady-state voltammetry. The liquid/liquid interface was supported at the tip of a microcapillary. A novel capillary design methodology has advantageously allowed the use of the same microcapillary in a number of different experiments. It is herein shown that the geometry of the microcapillary tip region is of critical importance in order to obtain reliable kinetic data. Both steady-state voltammetry and electrochemical impedance spectroscopy yielded approximately the same apparent standard rate constant of 0.2 cm s−1 for TEA+ transfer across the water/1,2-dichloroethane.