Electrical Conduction in Surfactant-Water-Nonaqueous Liquid Systems

Abstract

Electrical transient techniques were used to study conduction processes in low conductivity dielectric liquids containing surfactant and water. Experiments in nonblocking and blocking conditions permit differentiation between faradaic and nonfaradaic processes. Dependence of the transient currents on electric field, cell thickness, water and surfactant concentrations, electrode materials, temperature, and impurities is determined. Initial sweepout currents are ohmic over the full range of electric fields, 10-4-10V/μm, while background currents are nonohmic. Processes dominating the bipolar conduction include dissociation of neutrals, transport of charged species and their recombination, diffusion, and electrochemical reactions. Level of dissociation of surfactant molecules is in ppm range at millimolar concentrations of surfactant and water. Charged species are likely inverted bipolar micelles of surfactant and water molecules. Dissociation and electrochemical rates are strongly dependent on water concentration, and the activation energy for dissociation is 140 meV. © 1986, The Electrochemical Society, Inc. All rights reserved.