Study of the liquid-liquid equilibrium for aqueous systems containing choline bitartrate and 1-propanol at different temperatures and their performances in acetaminophen separation

The purpose of this research is study of the aqueous two-phase system composed of (1- propanol+ choline bitartrate + water) at T = (298.15, 308.15 and 318.15) K and atmospheric pressure (≈ 85 kPa). The use of this system for separation of acetaminophen, as a model drug was examined. First, the binodal data and tie-lines were determined for this system at the above mentioned temperatures. The effects of the tie-line length and temperature on the drug separation were also investigated. The Gibbs energies, enthalpies, and entropies are calculated from the cloud points at working temperatures in order to investigate the driving force of phase separation. In addition, the Merchuk equation and an empirical equation were used to show binodal results. The Setschenow equation and the non-random two-liquid (e-NRTL) model were used to fit the tie-line values.