Acetic acid is one of the most important carboxylic acids which is used in many reactions, including the synthesis of acetic esters. Because of industrial and environmental advantages, the separation of acetic acid from dilute aqueous solutions has recently received much attention. In this study we investigated liquid-liquid equilibrium of a ternary system consisted of water+ acetic acid+ organic solvent at various temperatures. In this study, various thermodynamic models (Non-Random Two-Liquid (NRTL) and Universal Quasi-Chemical (UNIQUAC) models) were used to predict the composition of component in aqueous and organic phases. In these models, intermolecular interaction were considered as a binomial function of reverse temperature. The parameters of two models were determined through the optimization of an objective function. Root mean square deviations of the NRTL and UNIQUAC models to predict the composition of the components in the ternary mixture of water+ acetic acid+ organic solvent were 0.0273 and 0.0422, respectively.
