(745a) Incorporation of Hydrophobic Silica Nanoparticles On Polyetherimide (PEI) Hollow Fiber Membranes for CO2 Absorption in a Membrane Contactor

The essential properties of the membrane used for contactor application for CO₂ capture by chemical absorbent include high hydrophobicity, high surface porosity with small pore size, low mass transfer resistance and high chemical resistance to the liquid absorbents. Asymmetric hollow fiber membrane prepared from the non-solvent induced phase separation (NIPS) process usually exhibits a relatively dense skin layer supported by a porous substrate. The most mass-transfer resistance in the membrane comes from the dense skin layer, while the porous substrate only provides mechanical support and fractional resistance. The pore size and pore size distribution of the skin layer significantly affect the CO₂ absorption flux and are associated with membrane wetting problem since the skin layer is in direct contact with the liquid absorbents.

In this presentation, we are going to report the fabrication of a highly porous polyetherimide (PEI) membrane with large pore sizes by using a triple-orifice spinneret in the hollow fiber spinning process, followed by novel incorporation of fluorinated silica (fSiO₂) nanoparticles into the top layer of the membrane to make the membrane surface highly hydrophobic and chemical resistant to prevent the membrane from wetting caused by the large pore size or/and less hydrophobic surface during the CO₂ absorption process.

 Experiments revealed that the highly porous and cellular surface structure of the PEI membrane is favorable for nanoparticle embedment. The fSiO₂ nanoparticles were incorporated on the PEI hollow fiber membrane, leading to a significant improvement in surface hydrophobicity, as evidenced by the advancing contact angle value of 123.2º, receding contact angle value of 107.2º, and contact angle hysteresis of only 15.9º. A stable CO₂ absorption performance by using sodium taurinate as the liquid absorbent was attained over a 60-day long-term test, indicating the great potential of PEI-fSiO₂ membranes in practical membrane contact application for CO₂ capture.