Synergistic effect of incorporating ZIF-302 and graphene oxide to polysulfone to develop highly selective mixed-matrix membranes for carbon dioxide separation from wet post-combustion flue gases

Graphene oxide (GO) nanosheets and zeolitic imidazole frameworks (ZIF-302) were synergistically integrated to glassy polysulfone (PSF) to fabricate mixed-matrix membranes (MMMs) to separate carbon dioxide from post-combustion flue gas stream. In order to optimize CO₂ separation performance of composite membranes form dry and wet gases, both nanofillers in varying compositions were incorporated into PSF to prepare MMMs using solution-casting technique. The flexible MMMs rendered homogeneous dispersion of fillers, improved polymer-filler adhesion, and thermally stable structure. Gas sorption analyses along with dry and wet gas permeation experiments demonstrated improved CO₂ permeability coupled with high CO₂/N₂ ideal selectivity of MMMs due to synergistic effect of nanofillers. The hybrid membrane containing 1 wt% GO and 30 wt% ZIF-302 nanofillers showed an optimum separation performance by providing a CO₂ permeability of 13 Barrers with CO₂/N₂ ideal selectivity of 52. The permeation characteristics of hybrid membranes were found to be better than already existing membranes and were not affected by humid conditions.