Facile fabrication of FAS-PDMS/PEEK composite hollow fiber membrane with honeycomb-like structure for CO₂ capture from flue gas by membrane absorption

In this study, as an efficient technology membrane absorption was applied with newly developed polyetheretherketone (PEEK) hollow fiber membrane (HFM) to remove CO2 from flue gas. To alleviate membrane wetting issue, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS) was integrated into polydimethylsiloxane (PDMS) and then crosslinked FAS-PDMS was coated on porous PEEK membranes to prepare composite membranes. Surface characterization verified that PDMS layer containing fluoroalkylsilane had been successfully formed on membrane surface. As mass ratio of FAS to PDMS in coating solution raised, an interesting honeycomb-like structure was observed dispersing on composite membrane surface. Meanwhile, water contact angle was improved from 90.0 degrees to 133.5 degrees indicating enhanced membrane hydrophobicity. The effects of gas and liquid flow velocities on CO(2 )absorption performance of FAS-PDMS/PEEK HFM were systematically studied. The highest CO2 removal efficiency of 99.6% was achieved when gas and liquid velocity were 0.027 and 0.019 m s(-1). When gas velocity raised to 0.110 m s(-1), the maximum absorption flux of 1.22 x 10(-4) mol m(-2) s(-1) and overall mass-transfer coefficient of 2.69 x 10-5 m s(-1) could be obtained. Compared with the original membrane, the CO2 absorption flux of FAS-PDMS-0.6 HFM was increased by 50.9%, and the performance had no degradation in 36 h test. This study provides a novel strategy to alleviate the membrane wetting problem during CO2 membrane absorption process.