Intensification of Amino Acid Ionic Liquids with Different Additives for CO2 Capture

Amino acid ionic liquids (AAILs) exhibit prominent merits for CO2 capture including biocompatibility and good stability, but they still suffer from several demerits, such as high viscosity and low molecular utilization. Therefore, it is critical to construct proper systems that can address these problems to enhance CO2 absorption of AAILs. In this work, three types of AAIL absorbent systems, DMEE (2-[2-(dimethylamino) ethoxy] ethanol)–AAIL, H2O–AAIL, and EG (ethylene glycol)–AAIL, are prepared with six AAILs that have different amino acids. The absorption performance of these absorbents is characterized to investigate the reinforcing effects of the additives on the absorption properties of AAILs. With temperatures ranging from 293 to 313 K, the CO2 capture studies on the binary systems reveal that AAILs present better absorption efficiency when their concentrations are 40 or 50 wt %. Based on the zwitterion reaction mechanism model and a thermodynamic model, the interactions of AAILs with H2O, DMEE, and EG systems for absorbing CO2 are discussed, respectively. The results obtained in this work indicate that AAIL–DMEE systems are promising candidates for CO2 capture since the interaction between AAILs and DMEE increases the capacity of AAILs and promotes kinetics.