Phase Diagram, Equilibrium Data, and Correlation for Aqueous Two-Phase System Formed by Tetrahydrofuran and Sorbitol

Abstract The importance of aqueous two-phase systems has been increased recently as a method with greater performance capability in separation and purification of biological products along with economic and operational advantages compared to the conventional methods. However, the thermodynamic modeling of some of applicable aqueous two-phase systems like tetrahydrofuran + polyols has not yet developed. In this study, liquid-liquid equilibrium data for tetrahydrofuran + sorbitol + water ternary system were obtained at 298.15 K. Validity of tie-line data were evaluated by Othmer–Tobias and Bancroft equations while correlative capability of data were investigated by the UNIQUAC and NRTL models. The results of RMSD (1.17% for NRTL (α = 0.5) and 2.12% for UNIQUAC models) clearly show that the NRTL model correlates with the experimental data more satisfactory rather than the UNIQUAC model. Additionally, the effect of pH was investigated on two-phase region and binodal curve changes. The results indicate that there is no significant change in the situation and shape of the binodal curve.