(401a) Polydimethylsiloxane Nanofilm-Enhanced Membrane Contactors for CO? Capture

Gas-liquid membrane contactors are attractive for CO₂ capture from flue gas due to process intensification; however, conventional contactors are based on hydrophobic porous membranes, which can be gradually wet by the liquid solvent, resulting in a dramatic decrease in CO₂ flux. Herein, we demonstrate a facile method for coating hydrophobic polydimethylsiloxane (PDMS) nanofilms on porous hollow fiber membranes (HFMs) using solutions containing 0.4–5% PDMS. The PDMS nanofilm covers the nanopores on the membrane surface and increases hydrophobicity, preventing pore infiltration by the liquid solvent and increasing the CO₂ flux. For example, coating the HFMs with a 5% PDMS solution enhances CO₂ mass transfer coefficient by more than 10 times, from 0.0020 to 0.028 cm² s^-1, and CO₂ permeance from 24 to 330 GPU, higher than most leading membrane contactors reported in the literature. CO₂ capture performance is also thoroughly investigated as a function of gas composition, gas flow rate, liquid flow rate, and transmembrane pressure, providing helpful guidance in designing next-generation membrane contactors for various gas separations. The PDMS NFC membrane contactors can be facilely prepared, and they might be useful for other important gas separations, such as olefin/paraffin and oxygen/nitrogen.