Hydrodynamic voltammetry at the liquid|liquid interface: facilitated ion transfer and the rotating diffusion cell

A new approach to the voltammetric investigation of facilitated ion transfer processes is reported. The technique uses a rotating diffusion cell approach to induce laminar flow in the organic phase of a liquid|liquid electrochemical cell. The interface between two immiscible electrolyte solutions (ITIES) was stabilised against rotation with either γ-alumina or a track-etched polyester membrane. The resultant voltammetry is shown to be consistent with the Koutecký–Levich equation enabling kinetic parameters associated with facilitated transfer of sodium by dibenzo-18-crown-6 across the water|1,2-dichloroethane interface to be evaluated. In particular, the use of the more hydrophilic alumina membrane permits the uncertainties regarding the use of the membrane-stabilised ITIES, namely the interfacial position, to be eliminated.