Liquid–liquid equilibria of aqueous two-phase systems of the ionic liquid brominated N-ethyl pyridine and sodium dihydrogen phosphate, sodium sulfate, ammonium citrate, and potassium tartrate at different temperatures: Experimental determination and correlation

Abstract

Liquid–liquid equilibrium data have been determined experimentally for aqueous two-phase systems of brominated N-ethyl pyridine ([EPy]Br) and sodium dihydrogen phosphate (NaH2PO4) at T=298.15, 308.15, 318.15, and 328.15K, and data have also been obtained for aqueous two-phase systems composed of [EPy]Br and sodium sulfate (Na2SO4), ammonium citrate (C6H5O7(NH4)3) or potassium tartrate (C4H4O6K2) at T=298.15K. The Merchuk equation was used to model the binodal data. The effects of temperature on the binodal curves and tie-lines were studied, and the two-phase area was found to expand with a decrease in temperature, while the slope of the tie lines slightly decreased with an increase in temperature. Furthermore, the effective excluded volume (EEV) values obtained from the binodal model for these systems were determined, and the salting-out abilities follow the order of Na2SO4>NaH2PO4>C4H4O6K2>C6H5O7(NH4)3. The Othmer–Tobias, Bancroft and several parameter equations were used to determine the correlations of the tie-line data. These models agreed well with the experimental tie-line data.