Electrochemical processes at liquid-liquid interfaces are of key importance in many extraction and phase transfer catalysis processes and measurements of ion transfer across liquid-liquid interfaces has traditionally been a domain of static experimental systems [1]. In this presentation, the use of both stationary and hydrodynamic liquid-liquid interfaces is compared. Voltammetric studies with immobilised droplets and with flowing liquids are reported. For example, two immiscible liquids, N-octylpyrrolidone (with blue dye) and aqueous 0.1 M NaClO₄ are passed through a micro-flow cell with rectangular duct. The resulting flow pattern is dependent on the flow rate and viscosity of each individual phase. Optical micrographs are presented and a plot of flow rate to flow width in the channel flow cell. At the interface of the two flowing liquids a triple phase boundary [2] with the gold electrode is established and electrochemical processes at this dynamic triple phase boundary are monitored. Electrochemically driven anion transfer processes are reported for simple and for more complex anions.

References

[1]  Bonne MJ, Reynolds C, Yates S, Shul G, Niedziolka J, Opallo M, Marken F, New J. Chem. 30 (2006) 327-334.

[2] Banks CE, Davies TJ, Evans RG, Hignett G, Wain AJ, Lawrence NS, Wadhawan JD, Marken F, Compton RG, Phys. Chem. Chem. Phys. 5 (2003) 4053-4069.