Use of the microchannel dimensions for studying assisted ion transfers at liquid-liquid supported microinterface

This paper confirms that, in the case of a more complex system like an assisted transfer of a metallic cation, the supported liquid-liquid microinterface behaves like a recessed or inlaid electrode depending on the transfer direction. This asymmetrical situation is a great advantage when studying the interfacial mechanism. We can thus determine in which phase the formation of the complex takes place. In this way, a well-known system, extraction of Zn(II) ions by 8-hydroxyquinoline, was studied. Three microchannels with various lengths but with an identical diameter were used to increase the asymmetrical situation. Voltammetric curves at various scan speeds give information on the diffusion pattern of complex transfer depending on the length of the microchannels. The complex is formed in the aqueous solution and so it is transferred into the organic solution. The stability constants of Zn(II)-HQ complex in water and in dichloroethane were evaluated. The transfer potential was also evaluated independently of the experimental apparatus. These results clearly show that this experimental device is a very well-adapted tool for studying systems, which present transfers of species across liquid-liquid interfaces.