Equilibrium phase behavior of aqueous two-phase systems containing 17R4/L64 and citrates.

The cloud points (CPs) of the copolymers 17R4 and L64 were first measured, and then the effects of salts ((NH4)3C6H5O7, K3C6H5O7) on 17R4 and L64 were researched. After finishing the work described above, the temperature (278.15, 283.15, and 288.15) K of aqueous two-phase systems was determined, which consist of 17R4-(NH4)3C6H5O7, 17R4-K3C6H5O7, L64-(NH4)3C6H5O7, and L64-K3C6H5O7. Finally, the liquid–liquid equilibrium (LLE) data of binodal curve and the tie line for 17R4-(NH4)3C6H5O7aqueous two- phase systems (ATPSs) 17R4-K3C6H5O7ATPSs, L64-(NH4)3C6H5O7ATPSs, and L64-K3C6H5O7ATPSs were obtained. Nonlinear fitting of the empirical equation was used for making the diagram. The results showed that the change in the size of the two-phase areas increases with the increase of temperature. The capacity of the salts to induce phase segregation follows the Hofmeister series, that is, K3C6H5O7 > (NH4)3C6H5O7. In addition, the findings also showed that the phase separation ability of 17R4 is better than that of L64. [ABSTRACT FROM PUBLISHER]