Apparent molar properties of hydroxyethyl ammonium based ionic liquids with water and ethanol at various temperatures

The density, ρ and speed of sound, u data for binary solutions of protic ionic liquids (PILs) namely N-butyl-2-hydroxyethyl ammonium formate (BHEAF) and N-butyl-2-hydroxyethyl ammonium acetate (BHEAAc) with water and ethanol, as a function of molality, m ranging from (0.1 to 0.8) mol.kg- 1 were measured from (293.15 to 318.15) K under 0.1 MPa pressure. The apparent molar volume, Vφ apparent molar isentropic compressibility, Ks,φ and limiting apparent molar expansion, Eφ∞ have been determined from experimental density and speed of sound data. The apparent molar volume, Vφ∞ and apparent molar isentropic compressibility, Kφ∞ at infinite dilution and corresponding empirical parameters (Sv, Bv, Sk and Bk) were calculated by using the Redlich-Mayer equation. The calculated Vφ∞ and Kφ∞ values indicate that ILs-ethanol interactions are stronger than ILs-water interactions. Further, thermodynamic properties of binary mixtures were explained on the basis of the influence of the anion structural contribution of protic ionic liquids.