Electrical Potential Between Dissimilar Clay Double Layers

Abstract

A model describing the electric double layers in clay-electrolyte systems containing particles with different surface charge densities was developed and used to calculate the film thickness of water present in a clay paste. The average water film thicknesses (-18/~) calculated by considering the clay to contain 9 groups of particles of different charge densities did not differ from those calculated by assuming one average charge density; provided the minimum potential between particles remained constant. These values, however, were higher than those obtained from gravimetric water determinations by about 30%. The overestimation of the average thickness of the water films by the theoretical model is most likely due to the assumption of a complete parallel arrangement of particles in the paste and the validity of the Gouy theory for double layers on clays.

The electric potential midway between overlapping clay flat double layers: A compilation of theoretical treatments

“…To the first group belongs the treatments of Verwey and Overbeek (1948), Devereux and de Bruyn (1963), Rawell-Colom (1962) andHogs et al (1966). To the second group belong the treatments due to Honig and Mu1 (1971), Usui (1973), Van Olphen (1963( ) and Heimy et al (1979( , 1981.…”

“…These latter treatments are more general since the interaction between similar double layers is a special case within the dissimilar treatment. As an example of the dissimilar treatments are these due to Devereux and de Bruyn (1963), Hogg et al (1966), Kur et al (1972 and Helmy et al (1981). The latter authors and Usui treat the problem at constant charge density while Devereux and de Bruyn and Hogg et al at constant surface potential.…”