Quantitative determination of potential distribution in Stern–Gouy double-layer model

Abstract

A quantitative determination of the potential distribution in the Stern–Gouy double-layer model for clay–water–electrolyte systems is presented. The surface potential, Stern potential, thickness of the Gouy diffuse layer, and distribution of electrical potential can be computed by knowing the required parameters, such as the cation exchange capacity, specific surface area, electrolyte concentration, and valence, temperature, and permittivity of the solvent (pore fluid). The factors influencing the potential distribution in the double layer are discussed. To demonstrate the applications of the Stern–Gouy model, two examples are presented. In the first example, the relationship between the double-layer thicknesses and hydraulic conductivities of a natural soil permeated by different organic compounds is established. In the second example, the electric potential distributions of three natural clays are presented. It is anticipated that the Stern–Gouy double-layer model will find broader applications in geotechnical and environmental engineering practice as the principles and computation methods become more familiar to engineers. Key words : Stern–Gouy electrical double layer, clay–water–electrolyte systems, soil behaviour, hydraulic conductivity, sensitivity.