(189bk) Prediction of Phase Behavior of Mixed Solvent Electrolyte Systems Using SAFT-VRE Morse EoS

In this study, the variable range version of electrolyte Statistical Associating Fluid Theory (SAFT-VRE) equation of state (EOS) has been considered to represent the phase behavior of mixed solvent electrolyte solutions. In this regard, the SAFT-VR Morse is considered for short-range dispersive interaction whereas the Debye-Huckle term is utilized for long-range electrostatic interactions between charged particles. The ion-specific parameters are obtained by the fitting to experimental mean ionic activity coefficient and solution density data of several 1:1, 1:2 and 2:1 types binary electrolytes. The thermodynamic properties and phase behavior of mixed solvent electrolyte solutions are predicted using the obtained ion-specific parameters in binary electrolyte solutions (salt-water solutions). It is well documented that the knowledge of dielectric constant of water-cosolvent mixture is essential to predict the thermodynamic properties of aforementioned systems. In this regard, a simple model is used to calculate the mixed solvent dielectric constant. The results show that, predictive capability of SAFT EoS’s could be improved using the suitable variable range dispersion term such as SAFT-VR Morse model.