Simplified electrostatic model for the thermodynamic excess potentials of binary strong electrolyte solutions with size-dissimilar ions

A model of electrodiffusion and osmotic water flow and its energetic structure

“…If the electrolyte solution is sufficiently dilute, the chemical potential µ k is given by (3.1) with ω equal to (2.1). However, deviations from ideality can be significant in electrolyte solutions, especially in higher concentrations [35,36,37,38,39]. Cross-diffusion (or flux coupling) in the bulk can also be significant in electrolyte solutions [30,31,32,33,34].…”

Comment on “The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion–ion correlations” [J. Chem. Phys. 133, 154507 (2010)]

“…The authors categorize previous studies in the field as "empirical modifications of the (Debye-Hückel) DH theory" [in which they cite my recent report on the smaller-ion shell (SiS) model 2 ], "more developed statistical mechanical theories," and "computer simulations." They offer a new theoretical approach ("II+IW") according to which μ i ex = μ i II + μ i IW , where subscript i denotes an ion, μ i ex is the excess chemical potential of the ion (causing the nonmonotonic behavior), μ i II is the contribution of the ion-ion interaction, and μ i IW is the contribution due to ion hydration.…”

Response to “Comment on ‘The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion–ion correlations’” [J. Chem. Phys. 134, 157101 (2011)]

“…Until this is possible, our model offers a realistic physical picture that includes all the important physical effects (ion-ion and ion-water correlations) that can be handled in the implicit solvent framework. PB treatments, such as the SiS theory of Fraenkel, 3,4 offer an easy-to-use alternative.…”

“…Fraenkel summarized the main points of our theory nicely. Also, he offered his smaller-ion-shell (SiS) model 3,4 as an alternative to our approach. In this response, we categorize our thoughts along a few main issues.…”

“…A comparison between MC and SiS results, therefore, is possible and done by Fraenkel. 3 Any agreement or disagreement, however, should be analyzed keeping in mind the possibility of cancellation of errors. In the case of electrolytes, for example, PoissonBoltzmann (PB) approaches underestimate the magnitude of both the (positive) hard core contribution and the (negative) electrostatic contribution (see the introduction of the paper of Torrie and Valleau 10 ).…”