Cholinium-amino acid ionic liquids as biocompatible agents for carbon dioxide absorption

Abstract

Cholinium-amino acid ionic liquids, (AAILs) based on six amino acids (proline [Pro], histidine [Hist], arginine [Arg], tyrosine [Tyr], glutamine [Gln], and Glutamic acid [Glu]) were synthesized and characterized as carbon dioxide absorbers. The carbon dioxide absorption capacity of these systems was investigated by QCM at temperatures 288.15, 298.15, 308.15 and 318.15 K and pressures 0–4 bars. The experimental CO2 absorption capacity in these systems were treated using the “deactivated model”. The some absorption parameters such as reaction equilibrium constant, Henry’s law constant, and absorption enthalpy were calculate to evaluating potential application of AAILs in CO2 Capturing. The CO2 absorption increases as pressure increases and decreases as temperature increases. The measurements manifest that absorption capacities of CO2 are in the sequence of [Cho][Arg] > [Cho][His] > [Cho][Gln] > [Cho][Glu] > [Cho][Tyr] > [Cho][Pro]. Among the studied systems, the highest CO2 absorption capacity was obtained for [Cho][Arg] due to the availability of more amino groups. Besides, CO2 absorbed chemically was confirmed by carbamate formation using 13C NMR and FT-IR spectroscopy.