The force between two planar electrical double layers

Abstract

An expression to calculate density profiles of ions between two charged plates is obtained through the hypernetted chain theory for pure electrolytes. In deriving this expression no superposition approximation is assumed. Separately, a contact theorem is derived from the Born–Green–Yvon equation for pure electrolytes. The combination of these two results allows the evaluation of the pressure which drives two charged plates apart, without assuming a superposition approximation. It is shown that for point ions, this theory reduces to the Deryaguin–Landau–Verwey–Overbeek theory.