Density, Viscosity and Excess Molar Volume of the Aqueous Ionic Liquid Tris(monoethanolamine) Citrate at 293.15–323.15 K

Abstract

A new ionic liquid, tris(monoethanolamine) citrate (TMEAC), was synthesized and characterized by FT-IR spectrometry and 1H NMR. Densities and viscosities of aqueous TMEAC mixtures were determined at 293.15–323.15 K and atmospheric pressure. The thermal expansion coefficient α, excess molar volume $$ V_{\text{m}}^{\text{E}} $$ , and excess logarithm of viscosity (ln η)E were calculated to evaluate the properties of the aqueous TMEAC ionic liquid. Correlation equations were fitted using these data for the calculation of density and viscosity. The results show that the density increases almost linearly as the mass fraction of TMEAC increases. The mass fraction of TMEAC has little influence on the density at low mass fraction. The viscosity changes significantly and sharply increases at mass fractions larger than 60 %. Both density and viscosity decrease as the temperature increases. The thermal expansion coefficient initially decreases and then increases with increase of the mass fraction of TMEAC. The change of the excess molar volume presents a W-shape. The excess logarithm of viscosity shows a variation where the value initially rises but subsequently drops. Values calculated from the correlation equations are in good agreement with the experimental values. The correlation equations can offer additional results for the aqueous TMEAC ionic liquid.