The implementation of ion-based ePC-SAFT EOS for calculation of the mean activity coefficient of single and mixed electrolyte solutions

Abstract

Following our previous work (Journal of Molecular Liquids 221 (2016) 904–913), the modified perturbed chain statistical associating fluid theory (ePC-SAFT) incorporated with Debye-Huckel term has been applied to calculate some thermodynamic properties of single and mixed electrolyte solutions. The applicability of this model has been investigated by calculation of the mean ionic activity and osmotic coefficients of electrolyte solutions as well as the water activity of regarded systems at different temperatures. Firstly, water-ion hydration has been taken into account independently by two individual strategies, i.e. ions can be considered as non-associating and associating compounds distinctly. Afterwards, a new set of ion parameters containing 31 common ions has been estimated using the experimental mean ionic activity coefficients and liquid densities of 78 binary electrolyte solutions in both strategies. The optimized parameters which have been utilized for prediction of single-salt aqueous electrolyte solutions MIACs up to 373.15 K are global and transferable to different salts. Eventually, it can be observed that not only the density of aqueous electrolyte solutions, but also MIACs, osmotic coefficients and water activity of single and mixed salt solutions are satisfactorily calculated by considering ions as association compounds over a wide range of temperature and salt concentration.