Ion binding by charged particles in their diffuse layer based on a symmetrized Poisson–Boltzmann approach

Abstract

The collective interactions in a four-component mixture of charged particles, the ions whose dissociation generates the charge of the particles, and the ions of a binary electrolyte are described by a symmetrized Poisson–Boltzmann (SPB) equation. The ion excesses in the diffuse layer are considered to be bound to the particles. The computations show that the binding numbers in the SPB approximation can differ considerably from those obtained on the basis of the conventional Poisson–Boltzmann equation. The structure of the mixture described by the SPB equations is examined and it is found that there are conditions under which the collective interactions generate and effective attraction among particles.