Creating Membrane‐air‐liquid Interface Through a Rough Hierarchy Structure for Membrane Gas Absorption to Remove CO 2

Membrane gas absorption (MGA) is widely accepted for separating CO2 from flue gas due to its superior advantages in overcoming the operational and economic issues encountered by conventional CO2 removal technologies. However, the efficiency may reduce when the membrane starts to wet after the prolonged operation due to the invasion of liquid absorbent into the membrane pores. Therefore, the synthesis of the superhydrophobic membrane is of great significance to enhance the wetting resistance of the membrane. It can also ensure continuous process optimization. In this work, two PVDF membranes synthesized from polymers of different molecular weights (HMW/g-PVDF and LMW/g-PVDF) had first used to evaluate the wetting resistance. As shown by the characterization tests, the HMW/g-PVDF membrane demonstrated the most critical wetting issue because the WCA was lower at 92 degrees, and the WCA had significantly reduced to 47 degrees after the swelling evaluation. Since HMW/g-PVDF has the lowest wetting resistance, it had been used to synthesis superhydrophobic membranes by using templated substrate (non-woven fabric). The produced membranes were immersed in water or an ethanol coagulation bath and successfully printed hierarchical structures on the membrane surface. The change in the surface structure produced a higher surface roughness, reaching 4.4 mu m, and exhibited a low contact angle hysteresis of 11.8 degrees. The patterned membrane with excellent wetting resistance also showed a higher CO2 absorption flux at 7.00 x 10(-2) mol/m(2)s. This means that the hierarchical structure existing on the membrane surface played a significant role in overcoming the shortcomings of membrane wetting in MGA.