STUDY OF MECHANISM OF ELECTROADSORPTION AT WATER-NITROBENZENE INTERFACE .I. ELECTROADSORPTION WITHOUT AN INORGANIC SALT

When an electric field is applied between two solutions of octadecyl trimethyl ammonium bromide in water and in nitrobenzene in partition equilibrium, modifications in the interfacial tension can be observed. From the law of variation of these modifications as a function of time, Blank proposed to explain this effect by an accumulation of matter due to the difference in the transport numbers of the ions in the two media of the salt used. It is shown, by direct measurement, that there is in fact accumulation of matter in the water in the vicinity of the interface. Besides, when octadecyl trimethyl ammonium picrate is employed, very large variations in the interfacial tension are observed although its ions have the same transport number in each medium. Because of the behavior of the curve (interfacial tension-applied potential) it does not seem possible to explain the phenomenon by electrocapillary adsorption, a hypothesis suggested by Blank, when the material studied is hardly soluble in one of the two media. © 1969.