Liquid-liquid equilibria of aqueous two-phase systems containing polyethylene glycol and sodium succinate or sodium formate

Liquid-liquid equilibria were determined for the PEG6000-sodium succinate-H2O, and PEG6000-sodium formate-H2O systems at 298.15 K. Furthermore, the binodal model was used for reproducing the experimental binodal data. The effective excluded volume values obtained from the binodal model for these two systems and other aqueous PEG6000-salt systems were determined; and the relation between these values and salting-out ability of different salts were discussed. Finally, a two-parameter equation and the NRTL model were used for the correlation of the obtained tie-line data. Good agreement was obtained with the experimental tie-line data with both models.