Liquid-Liquid Equilibrium in Aqueous Two-Phase (Water + PEG 8000+Salt): Experimental Determination and Thermodynamic Modeling

Aqueous two-phase systems have been of increasing importance as it method for separation and purification of biomaterials, such as proteins and enzymes, with economical advantages related to conventional methods However, the thermodynamic modeling of these systems is not fully developed yet, and the data in the literature are scarce. In this work, liquid-liquid e(equilibrium data are experimentally determined for aqueous two-phase (water + polyethylene glycol 8000 + sodium sulfate) and (water + polyethylene glycol 8000 + magnesium sulfate), at temperatures of (25 and 50) degrees C. The experimental data are correlated by the NRTL model for the activity coefficient. New interaction parameters were estimated by the Simplex method.