Enhanced ethanol recovery of PDMS mixed matrix membranes with hydrophobically modified ZIF-90

Abstract In this study, dodecylamine-modified zeolitic imidazolate framework-90 (DLA-ZIF-90) particles with enhanced surface hydrophobicity are synthesized and incorporated into the polydimethylsiloxane (PDMS) matrix to fabricate novel PDMS/DLA-ZIF-90 mixed matrix membranes (MMMs) for ethanol recovery via pervaporation. The successful modification of ZIF-90 particles is investigated via various characterization techniques. The morphology and physicochemical properties of the PDMS/DLA-ZIF-90 MMMs are studied and characterized. Compared to the PDMS MMM with unmodified ZIF-90, PDMS/DLA-ZIF-90 MMM exhibits enhanced morphology homogeneity and separation performance, contributed by the flexible inner channels of ZIF-90-DLA particles with enhanced adsorption selectivity, as well as the improved affinity between ZIF-90-DLA particles and PDMS matrix. The MMM with 2.5 wt% DLA-ZIF-90 loading shows the best performance with the optimal flux of 99.5 g m −2  h −1 and corresponding separation factor of 15.1 at 60 °C. The effect of operation temperature is also studied. The performance benchmarking shows that PDMS/DLA-ZIF-90 MMM exhibits superior pervaporation performance to most other PDMS-based membranes, and may therefore shed valuable insights to the development of high-performance ZIF-based MMMs for organic recovery.