Membrane-based CO 2 capture has emerged as a promising solution to mitigate global climate change. In this study, outside-in three-layer Pebax/PDMS/PSU composite hollow fiber membranes (HFMs) were developed for CO 2 /N 2 separation, guided by a bottom-up design strategy. To minimize the transport resistance of PSU substrates and intrusion of gutter-layer solutions, the effects of PSU concentration, nonsolvent additives, and bore-fluid composition during the spinning of hollow fiber substrates were systematically investigated. The optimized PSU substrate enabled the formation of PDMS/PSU composite HFMs exhibiting a high CO 2 permeance of approximately 4,400 GPU with a CO 2 /N 2 selectivity of 10.69 in pure-gas tests. Subsequently, the Pebax selective layer was deposited onto the PDMS gutter via dip coating, with precise control over plasma activation, withdrawal speed, and Pebax concentration to regulate surface wettability and coating hydrodynamics. Under optimal conditions, the resulting Pebax/PDMS/PSU HFMs achieved a CO 2 permeance of 1,366 GPU and a CO 2 /N 2 selectivity of 24.50 at a Pebax concentration of 0.40 wt%, and a CO 2 permeance of 1,075 GPU and a CO 2 /N 2 selectivity of 31.97 at 0.45 wt%. Importantly, the optimized membranes also demonstrated stable separation performance under mixed-gas (15/85 CO 2 /N 2 ) and humid conditions, delivering CO 2 permeances of 1,106 and 859 GPU with corresponding CO 2 /N 2 selectivity of 22.26 and 28.32 for 0.40 and 0.45 wt% Pebax coatings, respectively. This work highlights a scalable strategy that integrates the engineering of substrate morphology with hydrodynamics of selective-layer coating, providing an efficient way to develop next-generation composite HFMs for post-combustion CO 2 capture.
Chang et al. (Sun,) studied this question.