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.

Electroosmosis in homogeneously charged micro- and nanoscale random porous media

“…Simple proportional relationships have been obtained between the electroosmotic permeability and the zeta potential for electrical transports in soils [83,85] and in polymer composites recently based on the boundary-layer theory [86]. Here we analyze such effects using our numerical methods.…”

Hydraulic Conductivity of Nonprehydrated Geosynthetic Clay Liners Permeated with Inorganic Solutions and Waste Leachates

“…At the macro-scale, an increase in the bound water means a decrease in the hydraulic conductivity of bentonite (LagerwerŠ et al, 1969;Mesri and Olson, 1971). The volume of bound water has traditionally been described in the electric diŠusion double layer using the Stern-Gouy theory (Lambe, 1958;Mitchell, 1993;Shang et al, 1994). However, Stern-Gouy theory has signiˆcant limitations and does not accurately describe the crystal interlayer expansion, which is called the swelling (Norrish, 1954;Sposito and Prost, 1982;Low, 1987;Sposito, 1989;McBride, 1994).…”

Aluminium migration through a geosynthetic clay liner

“…For WTP alum based residual solid monofills, there is potential for aluminium to interact with the bentonite in a GCL in the form of cation exchange or porewater concentration increases. As predicted by the Stern-Guoy model (van Olphen, 1977;Mitchell, 1993;Shang et al, 1994) this could potentially cause the double layer thickness to decrease. Shackelford et al (2000) demonstrated the potential inhibition of double layer expansion of a sodium bentonite by showing significantly higher free swell values for distilled water (36 mL) compared to a 0.025 M AlCl 3 solution (11mL).…”