Density and Excess Molar Volume of the Protic Ionic Liquid Bis(2-hydroxyethyl)ammonium Acetate with Alcohols

Abstract Densities were determined for binary mixtures containing the protic ionic liquid
bis(2-hydroxyethyl)ammonium acetate [BHEAA] and an alcohol (methanol, ethanol, and 1-
propanol) at four different temperatures (293.15, 303.15, 313.15, and 323.15) K and ambient
pressure. Coefficients of thermal expansion and excess molar volumes were calculated from
the experimental densities. The excess molar volumes were fitted using the Redlich-Kister
polynomial equation. Negative deviations from ideal behavior of the excess molar volume
were observed for all systems investigated in this study. The results were interpreted in
terms of ion-dipole interactions and structural factors of the ionic liquid and alcohol. It was
observed that an increase of the alcohol carbon chain length led to lower interactions on
mixing.