Modelling of the thermodynamic and solvation properties of electrolyte solutions with the statistical associating fluid theory for potentials of variable range

Abstract

13/01/15 meb. Accepted version Ok to add after 12 months embarg

Development of intermolecular potential models for electrolyte solutions using an electrolyte SAFT-VR Mie equation of state

“…These advances have not yet been extended to include a description of electrolyte solutions. The purpose of our current work is to redress this: as will be shown, the introduction of a more rigourous physical description in the resulting SAFT-VRE Mie EOS allows for a reduction in the number of adjustable parameters, as compared with the previous SAFT-VRE formulation [21]. In addition, we develop electrolyte model parameters to represent the thermodynamic properties of a broad range of aqueous solutions of strong electrolytes including monovalent and divalent ions, and assess the performance of the models by making appropriate comparisons with available experimental data.…”

“…A simple treatment to account for the introduction of a charged species in a dielectric medium was provided by Born [25]. The Born contribution has now been incorporated within cubic and CPA EOSs [26,27], and, more recently, within the ePPC-SAFT [20] and SAFT-VRE [21] approaches. A non-primitive treatment that incorporates a polar solvent within a SAFT formalism has also been presented [17,[28][29][30].…”

“…A robust set of models for strong electrolytes was presented, providing an accurate description of a broad range of properties, including the Gibbs free energy of solvation, with the aid of the Born treatment. The model and theory proposed in [21] are based on an underlying squarewell interaction potential following the original SAFT-VR framework [33,34]. The SAFT-VR EOS has now been reformulated for the more versatile and realistic Mie [35] potential form together with an improvement in the underlying statistical-mechanical theory, now taken to third order in the high-temperature perturbation expansion [36].…”

“…In the late 1990s, molecular-based equations of state (EOSs), specifically the statistical associating fluid theory (SAFT) [8,9] and the cubic plus association (CPA) EOS [10], were combined with the classical approaches for charged species [1,5,6] and shown to provide an accurate description of the properties of strong electrolyte solutions [11][12][13], extending the range of applicability to more-concentrated solutions. The increasing accuracy in the description of the properties of the solvent and fidelity of the representation of the solvention interactions has been exploited in subsequent work [14][15][16][17][18][19][20][21][22].…”

“…The SAFT-VRE [13] approach has recently been revised [21] to acknowledge the specific importance of incorporating the Born [25] contribution to the free energy of the system, thus accounting for the charging process of the ionic species in the solvent medium. A robust set of models for strong electrolytes was presented, providing an accurate description of a broad range of properties, including the Gibbs free energy of solvation, with the aid of the Born treatment.…”