Studying the kinetics of the ion transfer across the liquid|liquid interface by means of thin film-modified electrodes

The kinetics of the ion transfer across the liquid/liquid interface is studied by means of a thin film-modified electrode in combination with square-wave voltammetry. The thin film-modified electrode consists of an edge plane pyrolytic graphite electrode covered with a thin film of a water immiscible electroinactive organic solvent containing a neutral redox probe and a suitable electrolyte. The overall electrochemical process, proceeding as a coupled electron-ion transfer reaction, is controlled either by the electron transfer across the graphite electrodel organic solvent or by the ion transfer across the organic solvent/aqueous electrolyte interface. The theoretical model enabling to distinguish the rate limiting step is developed. The theory is used to measure the kinetics of CIO4-, NO3-, Cl-, SCN-, Na+, K+, (CH3)(4)N+, and (C4H9)(4)N+ across the water/itrobenzene interface utilizing lutetium bis(tetratert-butylphthalocyaninato) as a redox probe. (c) 2005 Elsevier B.V. All rights reserved.