Effect of temperature on thermodynamic properties of protic ionic liquids: 2-hydroxy ethylammonium lactate (2-HEAL) + short hydroxylic solvent

Abstract

In this study, we have synthesized the protic ionic liquid 2-hydroxy ethylammonium lactate (2-HEAL), and investigated its volumetric and acoustic behaviour into different hydroxylic media (water, methanol and ethanol) at the temperature 288.15-323.15 K and atmospheric pressure. Total solubility of the ionic liquid into these solvents was observed at this range of temperature. Apparent molar volume and apparent molar isentropic compressibility values have been computed from the experimental data and fitted to a temperature dependent Redlich-Mayer equation. From these correlations, the limiting infinite dilution values of the apparent magnitudes have also been computed. Derived magnitudes such as isobaric expansibility and isothermal coefficient of pressure excess molar enthalpy were computed due to their importance in the study of specific molecular interactions among the ions and covalent molecules enclosed into mixtures. The measured experimental data were used to test the accuracy of prediction of different models (Mchaweh-Nasrifar–Moshfeghian model (MNM model) and the modified Heller temperature dependent equation (MHE) for density and Collision Factor Theory (CFT) for ultrasonic velocity). The obtained results indicate that ionic liquid interactions in water are weaker than in the studied alcoholic solutions, as previously observed in analogous protic ionic liquids.