Alternating electric current across a nitrobenzene—water interface. I. Adsorption kinetics

Abstract

The passage of an electric current through an ideal nonpolarizable interface is considered. Our system consists of two bulk phases, water and nitrobenzene; in both phases some surface active electrolyte, cetyltrimethyl ammonium bromide, was dissolved. The concentrations of this electrolyte in both phases were in equilibrium. A theory is developed when an ac flows through such an interface, yielding a relation between the amplitude of the variation in interfacial tension and the phase shift between variation of the ac and the variation in interfacial tension, as a function of the thermodynamic and kinetic parameters of the system. It was assumed that the adsorption is diffusion controlled. This theory was experimentally verified. Concerning the phase angles moderate agreement was obtained, but agreement was excellent for the amplitude of the variation in interfacial tension.