Facile Covalent Crosslinking of Zeolitic Imidazolate Framework/Polydimethylsiloxane Mixed Matrix Membrane for Enhanced Ethanol/Water Separation Performance

Abstract

The interfacial design is critical in preparing high-performance mixed matrix membranes (MMMs), especially for the separation of larger sized components from mixtures. Herein, a facile and novel strategy was employed to design covalently linked zeolitic imidazolate framework-8-polydimethylsiloxane (ZIF-8@PDMS) MMMs without interfacial defects by a one-step synthesis route for ethanol recovery from ethanol aqueous solution. In this strategy, 3-glycidyloxypropyltrimethoxysilane (GOPTS) worked as the covalent linker of PDMS and amine-functionalized ZIF-8 nanoparticles (AZIF-8) simultaneously. The chemical structures and morphologies of AZIF-8 and AZIF-8@PDMS MMMs were demonstrated by various characterization techniques. The results exhibited that AZIF-8 and the MMMs were successfully prepared and AZIF-8 as the filler displayed better dispersion in the PDMS matrix and compatibility with the PDMS matrix as compared to ZIF-8 or GOPTS-modified ZIF-8 (GZIF-8). Therefore, AZIF-8@PDMS MMMs showed more excellent separation performance than ZIF-8 or GZIF-8-filled MMMs. In particular, AZIF-8@PDMS MMM with 7 wt % AZIF-8 loading exhibited the highest separation factor of 17.7 and a comparable total flux of 585.6 g/m2 h at 40 °C with 5 wt % ethanol aqueous solution, which were improved by 176.6 and 34.5%, respectively, in comparison with the pristine PDMS membrane, breaking the “trade-off” effect between the flux and separation factor. This study might provide some new insights into the fabrication of high-performance MMMs for pervaporation recovery of various organic systems.