Influence of the binding of counterions on the structure of an electric double layer
in a flat capillary
Zharkikh N. I., Dukhin S. S.
A system of equations describing the spatial structure of a diffuse double layer (DL) in a flat, slit-shaped pore has been supplemented by the boundary condition resulting, from the macrokinetic description of the influence of the binding of counterions on the surface charge value. Simple formulas have been derived expressing the connection of the surface charge with the surface potential for the limit cases of high and low charges, of the strong and weak overlapping of diffuse atmospheres in a pore, low and high values of the binding constant.
Neutralization of the charge of ionic groups on the pore surface by counterions depends, not only on the value of the binding constant, the charge surface density, and the electrolyte concentration, but also on the pore width.
Within a wide range of parameters, the degree of neutralization of ionic groups during binding of counterions remains invariable with an unlimited decrease in the electrolyte concentration. Therefore, the concentration dependence of the structure of a DL in the course of binding counterions may be the same as that in the permanent charge model which has come to a wide use-earlier.
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Colloid and water chemistry institite, Academy of sciences of Ukraine, Kyiv
Received 10 Dec 1985
Published : Colloid Journal (Moscow), 1986, vol. 48, ¹ 6, p. 1142 – 1150.
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