Ion binding in polyelectrolyte solutions and the Poisson–Boltzmann equation

Abstract

An improved analytical solution of the Poisson–Boltzmann equation for polyelectrolyte solutions containing simple salt is presented. By considering the small-ion distribution in the cell model in relation to the Donnan effect, ion binding in polyelectrolyte solutions is investigated. It is shown that the ion binding effect is a consequence of the non-uniform distribution of small ions in the solution and is of statistical origin. Theoretical predictions about the magnitude of the ion binding effect are in essential agreement with experimental observations.