LAUSR

Abstract Biocompatible choline-based amino acid ionic liquids ([Cho][AA]s) were synthesized using neutralization choline hydroxide with amino acids. The sorption of carbon dioxide gas in three [Cho][AA]s, cholinium glycinate ([Cho][Gly]), cholinium alaninate ([Cho][Ala]), and cholinium valinate ([Cho][Val]) were investigated by quartz crystal microbalance (QCM) at temperatures from 288.15 to 318.15 K and pressures up to 4 bar. According to the sorption mechanism, the experimental CO2 sorption in [Cho][AA]s was correlated by a reaction equilibrium thermodynamic model. The thermodynamic parameters including reaction equilibrium constant, Henry’s law constant, enthalpy of physical sorption were calculated and compared with assessing the CO2 sorption performance in [Cho][AA]s. The results indicate that [Cho][AA]s with glycinate anion has better performance than others in carbon dioxide sorption. FT-IR spectra of [Cho][AA]s after CO2 sorption reveals that the chemical sorption of CO2 was take placed via carbamate formation. Density functional theory (DFT) calculations have been performed to affirm sorption energy of CO2 onto three [Cho][AA]s with different anions.