A nonlocal electrostatics model for ions in concentrated primitive electrolyte solutions

Abstract

In this paper, a nonlocal electrostatics model is developed for ions in primitive electrolyte solutions. When a charge renormalization process is applied to the Ornstein-Zernike(OZ) equation of an electrolyte mixture, an exact Debye-Hückel-like equation with the exclude volume effect is derived. Further assuming that linear response approximation applies to the solution, the electric potential ϕ(r) of an ion in the solution is further approximated by an extended Debye-Hückel equation ∇2ϕ(r)=κ2ϕ(r)+∫H(|r−r′|)∇2ϕ(r′)dr′, with H(r)=∑lMle−Λlr4πr the kernel function. The parameters, say κ, {Λl} and {Ml}, are determined in a self-consistent way to reproduce the bulk dielectric response function. The theory can reproduce the well known multi-Yukawa electric potentials in concentrated electrolyte solutions. Analytical expressions for induced charge densities, electric potentials and electrostatic energies are derived for spherical ions. The theory is applied to ions in concentrated electrolyte solutions, where the good agreement with hyper-netted-chain(HNC) theory demonstrates its validity.