Creating membrane‐air‐liquid interface through a rough hierarchy structure for membrane gas absorption to remove CO ₂

Abstract

Membrane gas absorption (MGA) is widely accepted for separating CO 2 from flue gas due to its superior advantages in overcoming the operational and economic issues encountered by conventional CO 2 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 , and the WCA had significantly reduced to 47 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 μm, and exhibited a low contact angle hysteresis of 11.8 . The patterned membrane with excellent wetting resistance also showed a higher CO 2 absorption flux at 7.00 Â 10 À2 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.

Carbon Capture from Flue Gas Based on the Combination of Non-Contact Hydrophobic Porous Ceramic Membrane and Bubbling Absorption

“…Even if a hydrophobic modifier modifies the membrane, the surface of the gas-liquid contact membrane is easily wetted at high temperatures. The wetting of membranes has been limiting the further development of gas-liquid contact membrane systems [19][20][21][22]. A hybrid system with a combination of non-contact membranes and bubbling absorption is proposed to address the problem of contact membranes.…”

Effects of fiber bundle nonuniformity on dehumidification performance and energy efficiency of pressure‐driven membrane modules

“…As a recently developing dehumidification method, membrane-based dehumidification is a permeation-separation process with a semipermeable membrane as a medium, which possesses a continuous dehumidification process, simple structure and great energy-saving potential. [12][13][14] Whereas the ideal energy cost of phase-change separation is the latent heat of water, the energy cost of permeability-based separation is only to maintain the differential pressure of water vapor across the membrane.…”

“…The large energy consumption of condensation dehumidification, the liquid droplets entrainment and supply air pollution of liquid‐desiccant dehumidification and the regeneration of solid adsorption bed cause unsatisfactory dehumidification performance and energy efficiency. As a recently developing dehumidification method, membrane‐based dehumidification is a permeation‐separation process with a semipermeable membrane as a medium, which possesses a continuous dehumidification process, simple structure and great energy‐saving potential 12‐14 . Whereas the ideal energy cost of phase‐change separation is the latent heat of water, the energy cost of permeability‐based separation is only to maintain the differential pressure of water vapor across the membrane.…”