Investigation of surface thermodynamics for DEAE-[N1111][Gly], DEAE-[Bmim][Gly] and DEAE-[Bmim][Lys] aqueous solutions

The surface tensions (γ) of 2-diethylaminoethanol (DEAE)–tetramethylammonium glycinate ([N 1111 ][Gly]), DEAE–1-butyl-3-methylimidazolium glycinate ([Bmim][Gly]) and DEAE–1-butyl-3-methylimidazolium l -lysinate ([Bmim][Lys]) aqueous solutions were measured by using the BZY-1 surface tension meter. The temperature ranged from 303.2   K to 323.2   K. The mass fractions of DEAE and amino acid ionic liquids (AAILs) respectively ranged from 0.30 to 0.50 and 0.025 to 0.075. A thermodynamic equation was proposed to model the surface tension and the calculated results agreed well with the experiments. The effects of temperature and mass fractions of DEAE and AAILs on the surface tension were demonstrated on the basis of experiments and calculations. The surface enthalpy and surface entropy were determined and their concentration dependences were illustrated.