Ion-Specific Hydration Effects: Extending the Poisson-Boltzmann Theory

TL;DR

This paper reviews how extending the Poisson-Boltzmann theory with phenomenological ion-specific terms helps predict ion-specific effects on forces in charged interfaces within salt solutions.

Contribution

It introduces a mean-field approach incorporating ion-specific hydration effects into the Poisson-Boltzmann framework for better predictions.

Findings

Modified Poisson-Boltzmann equations account for ion-specific interactions.

Ion hydration effects influence forces between charged interfaces.

Theoretical predictions align with experimental observations.

Abstract

In aqueous solutions, dissolved ions interact strongly with the surrounding water, thereby modifying the solution properties in an ion-specific manner. These ion-hydration interactions can be accounted for theoretically on a mean-field level by including phenomenological terms in the free energy that correspond to the most dominant ion-specific interactions. Minimizing this free energy leads to modified Poisson-Boltzmann equations with appropriate boundary conditions. Here, we review how this strategy has been used to predict some of the ways ion-specific effects can modify the forces acting within and between charged interfaces immersed in salt solutions.