Conductivity of electrolyte solutions: self-consistent Debye–Hückel–Onsager theory

Abstract

This study presents a novel approach to addressing the limitations in understanding the behavior of charged particles in solutions. The approach is based on the development of the Self-Consistent Debye–Hückel–Onsager (SCDHO) theory, which integrates the effects of non-local charge distributions using a Slater-type charge form factor model. This results in a modified Coulomb potential at short distances, unlike traditional approaches such as the classical Debye–Hückel–Onsager theory. The proposed method relies on explicit expressions derived from gradients of local chemical potentials rooted in classical density functional theory (DFT) and the Ornstein–Zernike formalism for correlation functions. Our theoretical framework enables the derivation of analytic equations that describe both correlation (aka relaxation) and electrophoretic contributions to total electric conductivity. Within the established theoretical framework, the model of smeared charges with Slater-type charge form factors provides an accurate predictive tool that can be applied to a wide range of ion valences, concentrations, and temperatures, including both aqueous and non-aqueous electrolyte solutions.