Counterion release and interaction of oppositely charged surfaces

Abstract

The interaction of two oppositely highly charged surfaces in an electrolyte solution and the number of released counterions from the slit between the surfaces were studied in terms of the anisotropic hypernetted chain and nonlinear Poisson-Boltzmann theories. Liquid theory predictions of the attractive pressure and release of counterions between the plates are larger than those of the mean field approach at low and moderate concentration of added salt. Further, at high salt concentration there is an opposite relationship of the two theories in their numerical results for the attractive pressure for all surface separations. These deviations of the predicted equilibrium properties arise both from the charge density and the ion size correlation effects included in hypernetted chain theory.