Vapor Pressure Measurement of Ternary Systems LiBr plus [Emim]l + H2O and LiBr plus [Dmim]l + H2O

Ionic liquids (ILs), 1-ethyl-3-methylimidazolium iodine [Emim]I and 1,3-dimethylimidazolium iodine [Dmim]I, were proposed as a novel potential solvent in traditional bromide aqueous solution (H2O + LiBr) in absorption refrigeration cycles. The vapor pressure data of two ternary systems H2O + LiBr + [Emim]I (mass ratio LiBr/[Emim]I = 4) at temperatures from 350.78 to 414.19 K and H2O + LiBr + [Dmim]I (mass ratio LiBr/[Dmim]I = 2) at temperatures from 350.69 to 409.63 K were reported by the boiling point method. The absorbent mass fractions are from 0.30 to 0.57 and 0.30 to 0.60, respectively. The measured data were correlated by using the Antoine -type equation, and the average absolute relative deviation (AARD %) between measured data and regression data was 0.54 and 0.39%. Compared with the vapor pressures of IL mixtures with the same organic cation, the vapor pressure order is LiBr + [Emim]I + H2O < LiBr + [Emim]Cl + H2O < LiBr + [Emim]Ac + H2O and LiBr + [Dmim]I + H2O < LiBr + [Dmim]Cl + H2O < LiBr + [Dmim]BF4 + H2O. Under experimental conditions, the hydrophilic properties of the iodine anion (I-) are better than those of the chlorine anion (Cr-), acetate anion (Ac-), and tetrafluoroborate anion (BF4-). Lower vapor pressure means stronger moisture absorption property. The proposed ternary mixtures have lower vapor pressures and can improve the absorption effect of the absorption system.