A modified Poisson-Boltzmann analysis of the solvent primitive model electrical double layer

Abstract

A modified Poisson-Boltzmann theory is used to analyse the steric effects of the solvent in the electrical double layer by considering a mixture of charged and uncharged hard spheres moving in a dielectric continuum near a plane charged wall. The uncharged system is described by Bogoliubov-Born-Green-Yvon theory. A comparison with preliminary Monte Carlo results implies that the theory gives qualitatively correct results for 1 : 1 electrolytes up to moderate electrolyte concentrations and surface charge, using a typical liquid density for the uncharged solvent. Comparisons are also made with some density functional results for 1:1 and 2:2 electrolytes.