Ion-specific hydration effects: Extending the Poisson-Boltzmann theory

In aqueous solutions, dissolved ions interact strongly with the surrounding water and surfaces, thereby modifying 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.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (145 K)Download as PowerPoint slideHighlights► Systematic extensions to standard Poisson-Boltzmann theory. ► Ion-specific hydration forces. ► Ions in responsive solvent environments and non-specific ion-solvent interactions. ► Non-electrostatic and specific ion-surface interaction.