Liquid–liquid equilibria of an aqueous two-phase system containing polyethylene glycol and sodium citrate: experiment and correlation

Liquid–liquid equilibria were determined for the PEG6000–sodium citrate–H2O system at 298.15, 308.15 and 318.15 K. Furthermore, the osmotic virial and the UNIQUAC equations with temperature-dependent parameters and with or without Debye–Hückel term were used to correlate the phase behavior of this system. Better quality of fitting of the LLE data was obtained with the virial model than the model of UNIQUAC. Finally, the effect of temperature on the liquid–liquid equilibria is studied.