Temperature Effect on the Phase Equilibrium of Polyethylene Glycol 2000 + Trilithium Citrate + Water Aqueous Two-Phase Systems at T = 288.15, 298.15, 308.15, and 318.15 K

Binodal and tie-line mass fractions for ternary polyethylene glycol 2000 + trilithium citrate + water aqueous two-phase systems (ATPSs) were reported at T = 288.15, 298.15, 308.15, and 318.15 K experimentally and modeled thermodynamically. It was found that the extent of the two-phase area of the liquid–liquid equilibrium region was increased as the temperature increased. Also, binodal curves were properly modeled with two nonlinear models, and both models have been successful in fitting the binodal data. Furthermore, the osmotic virial, modified nonrandom two-liquid (m-NRTL), and electrolyte-Wilson models have successfully been implemented in the modeling of the tie-line mass fractions. The quality of fitting with the electrolyte-Wilson and specially m-NRTL models is good, and the uncertainty of the modeled data is in the range of the uncertainty of the experimental data. Also, the salting-out coefficient (k s) of a Setschenow-type equation was applied as a quantitative measure of the salting-out ability. The results of the present work introduce a green and environmentally friendly ATPS for liquid–liquid extraction and purification purposes, which can be used in the separation and purification of drugs, biomaterials, and foods.