Electrochemical Instability in Liquid–Liquid Two-Phase Systems

Abstract

On the basis of the dependency of adsorption and partitioning of ionic surfactant on the phase-boundary potential (Á W O º), it is possible to understand in a unified manner various instability phenomena at the liquid«liquid interface in the presence of ionic surfactants, such as spontaneous emulsification, oscillation of Á W O º and interfacial tension, and irregularly increased currents on voltammograms of the transfer of surface-active ions across the interface. These instabilities are associated with the electrochemical instability, which defines a thermodynamically unstable condition at the liquid«liquid interface in terms of Á W O º and is a fundamental concept to understand the instabilities in the presence of ionic surfactants. The characteristic manifestations of the electrochemical instability, that is, the irregularly increased current on voltammograms in the transfer of surface-active ions, the spontaneous emulsification, and the spontaneous oscillation of Á W O º can be designed based on the criterion of the electrochemical instability.

Voltammetry of proteins at liquid–liquid interfaces

“…lipids) and synthetic surfactants have been investigated and in the latter case have been the basis of "electrochemical instability". 70,71 In the presence of proteins, surfactants have been exploited for the opportunity to assemble into reversed micelles in the organic phase, and into which the protein might transfer and reside, thus providing it with a more hospitable environment than transfer into a pure organic phase. Although reverse-micelle extraction of proteins has been used in protein science and technology for many years, 72,73 Karyakin and co-workers [74][75][76] were the first to study this from an electrochemical perspective, seeking to achieve electrochemical formation of reverse micelles and the electrochemical extraction of proteins into these.…”

Emulsification at the Liquid/Liquid Interface: Effects of Potential, Electrolytes and Surfactants

“…[23] Experimental Section Electrochemical measurements were performed at room temperature using ac omputer-controlled Autolab Potentiostat (Metrohm Autolab B.V.N etherlands) with iR compensation. [23] Experimental Section Electrochemical measurements were performed at room temperature using ac omputer-controlled Autolab Potentiostat (Metrohm Autolab B.V.N etherlands) with iR compensation.…”

“…By furthere xploring the emulsification process at the interface electrochemically and optically,ad eeper understanding of the ubiquitous phenomenaa ssociatedw ith the unstable interfaces such as the occurrence of spontaneous emulsification with the change in phase boundary potential at the oil/water interfacewill emerge. [23]…”

Spontaneous interfacial tension changes at the interface of a ZnCl2 nitrobenzene solution and aqueous stearyltrimethylammonium chloride solution

“…Reported applications of such spontaneous interfacial motion include the extraction of dynamics energy [5,8], generation of biological models [9], and development of a new model of nonequilibrium physics described in the context of electric capillary force [10]. For applying this phenomenon in engineering, information regarding the kind of material that can be used is very important.…”