Comparison of facilitated transport behavior and separation properties of membranes with imidazole groups and zinc ions as CO sub(2) carriers

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