Electrochemical Study of Solvent Extraction Based on Ion Transfer at the Aqueous/Organic Solution Interface

Abstract

A voltammetric study of ion transfer across an interface between two immiscible electrolyte solutions (ITIES) such as water (W) and an organic solution (O) interface (W/O) enables the observation of the dynamic feature of the ion transfer process based on the measurement of the current vs potential relationship from which one can determine simultaneously the transfer energy and the amount of the ion transferred. Thus, a voltammetric study of the ion transfer processes involved in a solvent extraction system provides fundamental insights into the thermodynamics, kinetics and the mechanism of solvent extraction. The present review highlights (i) the fundamental aspects of the ion transfer reaction across the ITIES, (ii) the principle of and procedures for the electrochemical observation of the ion transfer at the ITIES, (iii) various studies of the ion transfer processes involved in ion-pair extraction and chelate extraction systems, and (iv) a novel method for the separation of ions on the basis of the electrolytic ion transfer reaction.

Catalytic Effect of Ionic Surfactants on the Extraction Rate of Nickel(II) and Palladium(II) with 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol in the Toluene/Water System

“…Thereafter interfacial complexation in various solvent extraction systems has been studied by many researchers [3][4][5][6]. However, there have been a few studies on catalytic reactions at the interface [7][8][9][10], although acceleration of the extraction is a subject of significant interest for real industrial extraction processes.…”

Trapped in the coordination sphere: nitrate ion transfer driven by the cerium(iii/iv) redox couple

“…Redox-driven ion transfer between phases underpins many natural and man-made processes, including ion transfer through biological membranes, electrochemical catalysis, ion sensing and separations. [1][2][3][4][5][6] In the latter, ions are separated between oil and water phases by changing the oxidation state, causing ions to migrate through the interface. [6][7][8][9][10][11][12] The electrochemistry underpinning such systems is complex as the ion transfer potential is inherently linked to the redox potential of the active species.…”

“…[1][2][3][4][5][6] In the latter, ions are separated between oil and water phases by changing the oxidation state, causing ions to migrate through the interface. [6][7][8][9][10][11][12] The electrochemistry underpinning such systems is complex as the ion transfer potential is inherently linked to the redox potential of the active species. [13][14][15] Because of this entanglement, there is lacking a fundamental strategy for designing redox-driven multiphasic ion transfer separation systems with potentials that are programmed at the molecular scale.…”

“…Without such knowledge, the development of crucial biphasic electrochemical technologies for liquid-liquid ion extraction systems is fundamentally hindered. 6,[16][17][18]28 Here we investigate how changes in ion coordination environments correlate with electrode potentials in liquid-liquid redoxdriven ion transfer systems, see Fig. 1b.…”