Effect of Temperature on the Phase Equilibria of Poly(vinylpyrrolidone) 10000+Trilithium Citrate plus Water Aqueous Two-Phase System and Partitioning of Curcumin at T=298.15, 308.15, and 318.15 K

Curcumin is a natural product traditionally used as a spice that has a great potential for being used as a drug of natural origin. The partitioning of curcumin in an aqueous two-phase system composed of the aqueous solutions of poly(vinylpyrrolidone) 10000 (PVP10000) and trilithium citrate was studied at T = 298.15, 308.15, and 318.15 K. The binodal and tie-line compositions were measured and modeled. The tie-line compositions were modeled successfully using osmotic virial and especially e-Wilson and e-NRTL models, where the deviation percent between the calculated and the experimental tie-line mass fractions was found to be in the range of 0.005-0.03 for the e-Wilson model and 0.02-0.05 for the e-NRTL model, which are in the range of the experimental uncertainties. The high values of the partition coefficient (D) showed the high tendency of curcumin to be extracted from a salt-rich to a polymer-rich phase. The minimum and maximum D values of 11.7 and 21.2 were found at T = 318.15 and 298.15 K, respectively. Moreover, the minimum and maximum extraction efficiencies (E%) of similar to 81 and 90% were shown at T = 318.15 and 298.15 K, respectively. Both obtained D and E% values decreased by increasing the temperature, and the best partitioning results were obtained for the tie-lines presented in the middle range of the tie-line compositions.

Automated summary

Curcumin partitioning behavior in an aqueous two-phase system was investigated, showing high tendency to be extracted to the polymer-rich phase, and the distribution coefficient and extraction efficiency decreased with increasing temperature. The tie-line compositions were successfully modeled using e-Wilson and e-NRTL models.