Fabrication of hydrophobic ZIFs based composite membrane with high CO2 absorption performance

The membrane contactor has been considered an effective device to capture CO 2 , but its performance is limited by membrane wetting phenomena. In this work, the ZIF-8/ZIF-L (zeolitic imidazolate framework) based composite membrane with excellent hydrophobic stability and CO 2 permeability was successfully fabricated by coating the dense layer on the porous PVDF (polyvinylidene fluoride) substrate. The dense layer was developed by evenly incorporating ZIF-8 nanocrystals and ZIF-L nanosheets into the polydimethylsiloxane (PDMS) polymer. The as-prepared membrane possessed competitive hydrophobicity with a water contact angle (WCA) of 131.8°. And after a ten-day immersion test in CO 2 absorbent, the WCA only declined by 9.8%, exhibiting excellent hydrophobic stability. Besides, the CO 2 permeability of the composite membrane was 61.8×10 −8 ·mol·m −2 ·s −1 ·Pa −1 with an ideal CO 2 /N 2 separation factor of ∺20, which was effectively improved in comparison with the control membrane. In the CO 2 absorption experiment, the prepared membrane achieved the competitive CO 2 flux of 3.02×10 −3 ·mol·m −2 ·s −1 when the liquid velocity was 0.25 m·s −1 and displayed robust long-term operating stability. Finally, the AC impedance technique was applied to continuously monitor the wetting state of composite membranes, which further investigated their anti-wetting ability.