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

• Water-stable PSF/GO/ZIF-302 MMMs were prepared via solution-casting technique.
• GO and ZIF-302 nanocrystals were homogeneously dispersed in PSF with good interfacial filler–matrix adhesion.
• Collegial effect of incorporating GO and ZIF-302 nanocrystals efficiently improved separation performance of CO2 from N2.

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.

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