A further treatment of the exclusion-volume term in the modified Poisson–Boltzmann theory of the electric double layer

The first equation of the Born–Green–Yvon hierarchy of distribution functions is used to calculate the exclusion-volume term in the modified Poisson–Boltzmann theory. Comparisons with Monte-Carlo calculations indicate that this theory is an improvement upon the modified Poisson–Boltzmann theory based on a bulk density expansion of the exclusion-volume term, especially at the higher values of the surface charge and electrolyte concentration. Some imaging results for a metallic and insulating wall are also presented.