Volumetric and Surface Properties of Aqueous 1-Alkyl-3-methylimidazolium Propionate {[C_nmim][Pro] (n = 4, 5, 6)} Ionic Liquids at 298.15 K

Abstract

Three propionic acid ionic liquids (PrAILs), 1-alkyl-3-methylimidazolium propionate ([C n mim][Pro] (n = 4, 5, 6)), were prepared by the neutralization method and characterized by 1 H NMR spectroscopy. The values of the densities and surface tensions of aqueous [C 4 mim][Pro], [C 5 mim][Pro], and [C 6 mim][Pro] with various molalities were determined at 298 K, and the values of the parachor for these solutions were calculated. The values of the apparent molar volumes and partial molar volumes at infinite dilution for the ILs were estimated in terms of Pitzer's theory. With the use of Li's model of surface tension and the empirical equation of the parachor, the values of the surface tensions of these aqueous solutions for three PrAILs were estimated and the estimated values were in good agreement with experimental ones.

The molar surface Gibbs free energy and its application for aqueous solutions of ionic liquid N-butyl-pyridinium dicyanamide [C4py][DCA]

“…[26] at 298.15 K (in the following, these systems are called other aqueous ILs) using the literature data [25,26] and listed the results in Tables 4 and 5 . S5).…”