Liquid–liquid equilibria of aqueous two-phase systems containing polyethylene glycol 4000 and di-potassium tartrate, potassium sodium tartrate, or di-potassium oxalate: Experiment and correlation

Phase diagrams and liquid–liquid equilibrium (LLE) data of aqueous polyethylene glycol 4000 (PEG4000) + di-potassium tartrate or potassium sodium tartrate and aqueous PEG4000 + di-potassium oxalate systems have been determined experimentally at 298.15 K. Furthermore, the Merchuk equation was used to correlate the binodal data; Othmer–Tobias and Bancraft, Setschenow and extended NRTL equations were used to fit the tie-line data of these systems. Finally, the effects of the type of salt on LLE are discussed.