Equilibrium Properties of a Model Electrolyte Adsorbed in Quenched Disordered Charged Media: the ROZ Theory and GCMC Simulations

Abstract

We present a theoretical study of the quenched−annealed system consisting of an annealed +1: −1 electrolyte and a disordered quenched matrix modeled as a charge and size asymmetric +Z: −1 electrolyte, with Z = 4 or 10. The annealed electrolyte is in thermodynamic equilibrium with an external reservoir of electrolyte at concentration cb such that the chemical potentials of the confined and external electrolytes are equal. Both the matrix and the adsorbed electrolyte are modeled as charged hard spheres in a dielectric continuum. The replica Ornstein−Zernike (ROZ) equations, supplemented by the hypernetted chain (HNC) approximation, are solved for this system. The effects of charge and size asymmetry of the matrix ions, their concentration, the prequenched conditions on the pair distribution functions, and the thermodynamic properties of the annealed electrolyte are investigated. The concentration of adsorbed electrolyte c1 is calculated as a function of the concentration of external electrolyte cb. For lo...