Analysis of Surface Thermodynamics for Amino Acid Ionic Liquid–1-Dimethylamino-2-propanol Aqueous Blends

In this work, the surface tensions (γ) of the aqueous blends of 1-dimethylamino-2-propanol (DMA2P) + amino acid ionic liquids (AAILs) were studied using the Wilhelmy plate method at temperatures from 303.2 to 323.2 K and atmospheric pressure. The AAILs include tetramethylammoniumglycinate ([N1111][Gly]), 1-butyl-3-methylimidazolium glycinate ([Bmim][Gly]), and 1-butyl-3-methylimidazolium-l-lysinate ([Bmim][Lys]). The concentrations of DMA2P and AAILs were varied between 0.300 and 0.500 wt % and 0.025 and 0.075 wt %, respectively. A thermodynamic correlation approach with respect to the mass fraction and temperature was employed to correlate the surface tension of DMA2P–AAILs aqueous solutions. The surface entropy (SS) and surface enthalpy (HS) were calculated from the analytical formulation, and their variation with mass fraction and temperature was demonstrated. The effects of the types of AAILs on the surface properties were also analyzed and compared.