Kinetic Analysis of the Solvent Extraction of Cadmium(II) Complexes Using a Cadmium-deposited Recessed Microelectrode and Confocal Fluorescence Microscope.

Using a Cd-deposited microelectrode, an electrochemically generated Cd(II) ion in a micro-water phase was reacted with 5-octyloxymethyl-8-quinolinol (HCQ) in 1,6-dichlorohexane. The fluorescence intensity of Cd(CQ) near the water/oil interface (I) was analyzed under a confocal fluorescence microscope. The rate of decrease of I was independent of the HCQ concentration and pH, but was influenced by the phase-boundary potential between the water and oil phases, suggesting that Cd(II) extraction is governed by Cd(CQ) desorption at the interface.