Silane-Modified ZIF-8/PDMS Mixed Matrix Membranes for Sorption-Selective Furfural Recovery via Pervaporation

Zeolitic imidazolate framework-8 (ZIF-8) was incorporated into polydimethylsiloxane (PDMS) to fabricate mixed matrix pervaporation membranes for furfural recovery from aqueous solutions. The effects of filler loading on membrane morphology, physicochemical properties, and separation performance were systematically investigated. ZIF-8 nanoparticles exhibited excellent dispersion within the PDMS matrix and enhanced both membrane hydrophobicity and furfural sorption capacity, resulting in increased furfural permeability with increasing filler loading. Surface modification of ZIF-8 with silane functional groups (SM-ZIF-8) further improved furfural affinity, preferentially promoting furfural transport across the membrane. Compared to pristine PDMS membranes, the incorporation of ZIF-8 and SM-ZIF-8 increased furfural permeability by approximately 270 and 550%, respectively, while the separation factor improved 2–2.5-fold. The best membrane performance was achieved at 15 wt % SM-ZIF-8 loading, yielding a furfural permeability of 37.14 × 105 Barrer and a separation factor of 26.84. This resulted in a 10-fold enrichment of furfural, elevating its concentration from 3 wt % in the feed to 31 wt % in the permeate. Permeation studies revealed that the separation mechanism was governed by sorption selectivity, which can be effectively tuned through appropriate filler selection and modification. This work demonstrates the promising potential of surface-modified ZIF-8/PDMS membranes for efficient furfural recovery via pervaporation.