Thermodynamics of mixtures includes ionic liquid 2-hydroxyethylammonium propionate [2-HEAPr] + 1-propanol, 3-amino-1-propanol [AP], 1-amino-2-propanol [MIPA], and monoethanolamine [MEA] were studied. Density ρ, speed of sound u, and refractive index nD of pure and mixtures were measured at T = (298.15, 308.15, 318.15) K. Excess molar volume VEm , excess partial molar volume VEm ,i , excess thermal expansion coefficient αE, isothermal coefficient of excess molar enthalpy (∂Hm ∂P )T,x, deviations in isentropic compressibility Δ ks, and refractive index Δ nD were calculated and data correlated with Redlich-Kister polynomial relation. The Prigogine-Flory-Patterson (PFP) and Extended Real Associated Solution (ERAS) models were applied to analyze intramolecular and intermolecular interactions between like and unlike molecules. The accuracy of theoretical models were found to be in agreement with empirical results. Finally, the study confirmed the structures of the ILs using FT-IR and HNMR analysis.
