Measurement and Correlation of the Phase Diagram Data for PPG400 + (K3PO4, K2CO3, and K2HPO4) + H2O Aqueous Two-Phase Systems at T = 298.15 K

Experimental liquid−liquid equilibrium (LLE) binodal curves, tie-lines, and plait points were obtained for the PPG400 + salt (K3PO4, K2CO3, and K2HPO4) + H2O systems at T = 298.15 K. The Merchuk equation was used to correlate the binodal data of the investigated systems. Also, the effect of salt on the phase-forming ability has been studied based on the effective excluded volume (EEV) values from fitting the binodal data to the binodal model developed by Guan, and the salting-out abilities of the anions are in the order of PO43− > HPO42− > CO32−, which may be related to the Gibbs free energy of hydration of the ions (ΔhydG). Furthermore, tie-line compositions were correlated using the Setschenow-type, Othmer−Tobias, and Bancroft equations, and the parameters are reported.