Modeling of Liquid-Liquid Equilibria of Aqueous Alcohol + Salt Systems Using a Modified NRTL

The modified NRTL (m-NRTL) model is used to represent the excess Gibbs free energy of aqueous (alcohol + electrolyte) solutions. In this work, the m-NRTL model, previously developed for representation of vapor-liquid equilibria for (polymer + salt + water) systems, has been extended to represent liquid-liquid equilibria of (alcohol + salt + water) systems. The proposed extension is a modified form/version of the extended NRTL model. The model provides a thermodynamic framework for both correlating and predicting the phase equilibrium of complex systems containing both electrolytes and alcohol. The utility of the model is demonstrated with successful representation of (liquid + liquid) equilibrium of several (alcohol + salt + H2O) systems at different temperatures. The liquid–liquid equilibria of the ternary systems involved and the mean activity coefficients of the salt + water systems were used simultaneously to obtain the adjustable parameters. For the several aqueous systems containing an alcohol and a salt the performance of this m-NRTL model was examined at the correlation of LLE data. In addition, the results of the suggested model were compared with those obtained using the Setschenow-type equation, extended Wilson (e-Wilson) and extended NRTL (e-NRTL) models.