Aqueous biphasic systems containing sodium L-tartrate dihydrate and PEG, experimental and application of extended thermodynamic models

Abstract

In the current study, liquid-liquid equilibrium data of aqueous two-phase systems (ATPS) containing polyethylene glycol at the different molecular weights (1000, 2000, 6000, and 8000) - sodium L-tartrate dihydrate - water at 298.15 K were obtained. Binodal curves of mentioned systems have been determined and the effect of the molecular weight of polymer on binodal curves, tie-lines, and two-phase region sizes was studied. The results showed that increasing the molecular weight of the polymer enhances the biphasic area of the system. Also, an extended UNIQUAC equation and an extended form of Virial expansion models as new models of activity coefficient were examined to predict the phase equilibria of mentioned systems. The fitted binary interaction parameters of the model were reported. Both investigated models were capable to correlate the VLE and LLE data of the pertinent binary and ternary systems successfully. It could be observed that the extended Virial model leads to a better presentation of the data in comparison to the extended UNIQUAC model.

Keywords

• Aqueous biphasic system
• Liquid-liquid equilibrium
• Polyethylene glycol
• Sodium L-tartrate dihydrate
• Thermodynamic modeling