Improved CO2 separation performance and interfacial affinity of composite membranes by incorporating amino acid-based deep eutectic solvents

Increasing concentration of CO2 in the atmosphere has drawn attention to the mitigation of global warming. In order to develop an efficient and cost-effective CO2 capture technology, a defect-free asymmetric composite membrane based on amino acid-based deep eutectic solvent (ADES) and Pebax 1657 was assembled. ADES is a novel alternative to ionic liquids for CO2 capture, synthesized from natural substances through simple processes, which has the basic characteristics of ionic liquids and is environmentally friendly. The asymmetric distribution of ADES in the membrane is achieved by solvent compatibility design. Under the synergistic effect of multiple factors, the composite membrane shows outstanding gas separation performance. Compared with the neat Pebax membrane, the CO2/N2 selectivity of the composite membrane is increased by 17%, while the CO2 permeability is reduced by less than 0.6%. Density functional theory (DFT) calculations were also conducted to investigate the interaction mechanism between composite membrane and gas molecules.