Covalent organic frameworks filled Pebax hybrid membrane for efficient toluene/N2 separation

Hybrid membranes hold significant potential in the efficient recovery of aromatic volatile organic compounds (VOCs). The advanced fillers with high aromatics affinity and polymer compatibility are in urgent demand. In this study, covalent organic framework nanosheets (COFNs) were introduced into poly (ether block amide) (Pebax®2533) to fabricate hybrid membranes. The long-range ordered pore structure, tunable functional groups and organic attributes of COFNs enhanced the affinity of membrane towards aromatic VOCs, the transport of VOCs within the membrane as well as the interactions between COFNs and Pebax. The hybrid membrane filled with TpPa-COOH COFNs exhibited a noticeable improvement in both selectivity and permeability compared to pure Pebax membranes. Particularly, when the content of TpPa-COOH COFNs was at 4 wt%, the membrane demonstrated excellent separation performance for a 2.7 mol% toluene/N2 mixture, wherein the toluene permeability of membrane was 6.7 × 10−7 mol μm m−2 s−1 Pa−1 and the selectivity was 674. This study expanded the application scenarios of COFs-based hybrid membranes and provided a new approach for the design and fabrication of VOCs recovery membranes. [Display omitted] •Covalent organic framework nanosheets (COFNs) were synthesized.•COFNs were used as fillers to make Pebax hybrid membrane for aromatic VOCs recovery.•Hydrogen bonding between COFNs and Pebax ensured the uniform dispersion of fillers.•The affinity of COFNs toward VOCs was regulated by the functional groups of COFNs.•Pebax-TpPa-COOH-X membranes exhibited superior separation performance.