Incorporating\nMixed-Ligand\nZeolitic Imidazolate Framework\ninto Polydimethyldiethoxysilane (PDMDES) Membrane for Enhancing Alcohol\nPervaporation Recovery

In the present study, a zeolitic\nimidazolate framework\nwith mixed\nligands, ZIF-8-90, was synthesized and embedded into an ultrathin\npolydimethyldiethoxysilane (PDMDES) matrix to prepare a ZIF-8-90/PDMDES\nmixed matrix membrane (MMM) for the enhanced recovery of alcohols\nfrom dilute aqueous solutions via pervaporation, using a facile solution\ncoating method. The synthesized ZIF-8-90 particles demonstrated superior\nhydrophobicity and thermal stability compared to those of both ZIF-8\nand ZIF-90 particles. Furthermore, the hydrophobicity, thermal stability,\nand sorption ability for alcohols of the ZIF-8-90/PDMDES MMM were\nsignificantly improved, attributed to the incorporation of mixed-ligand\nZIF-8-90. Notably, the MMMs displayed two distinct cross-sectional\nmorphologies: (1) ZIF-8-90 particles enveloped by PDMDES polymer forming\nfiller bulges and (2) an accumulation of ZIF-8-90 particles resembling\na brick-wall-like structure. The MMM incorporating 2.5 wt % ZIF-8-90\nexhibited the optimal performance among the fabricated MMMs with various\nZIF-8-90 loadings, spanning from 0 to 3.2 wt %. The effects of feed\nconcentrations and operation temperatures were systematically investigated.\nThe best pervaporation performance was achieved using the 2.5 wt %\nZIF-8-90-filled MMM, effectively separating a 5.0 wt % ethanol/water\nmixture at 60 °C, yielding a distinguished total flux of 7.70\nkg·m<sup>–2</sup>·h<sup>–1</sup>, an improved\nseparation factor of 9.96, and an extraordinarily high PSI of 68.99\nkg·m<sup>–2</sup>·h<sup>–1</sup>. Comparative\nanalyses highlighted the superior pervaporation performance of the\nZIF-8-90/PDMDES MMM over ZIF-8/PDMDES MMM, ZIF-90/PDMDES MMM, and\nother MMMs, underscoring its potential for practical applications\nin alcohol recovery.