Comparison of facilitated transport behavior and separation properties of membranes with imidazole groups and zinc ions as CO2 carriers

Two kinds of membranes using imidazole groups and Zn ions respectively as CO 2 carriers are designed to investigate different facilitated transport behaviors and the concomitant separation properties. Poly(N-vinylimidazole)@CNT (PVI@CNT) and Zn-poly(N-vinylimidazole)@CNT (Zn-PVI@CNT) nanoparticles are synthesized via precipitation polymerization then incorporated into polyimide to prepare hybrid membranes. PVI@CNT filled membrane shows CO 2 facilitated transport behavior and distinctly enhanced CO 2 separation property with a maximum CO 2 permeability increment of 90% at humidified state, which is attributed to the nucleophilic addition reaction between imidazole group and CO 2 . Zn-PVI@CNT filled membrane shows CO 2 facilitated transport behavior and distinctly enhanced CO 2 separation property with a maximum CO 2 permeability increment of 93% at dry state, which is attributed to the π complexation reaction between Zn ion and CO 2 . The different facilitated transport behaviors of these two membranes are further analyzed for the rational design and intensified separation properties of membrane materials.