Novel MOF-303 integrated polymer membrane for efficient separation of azeotropic methanol-MTBE mixtures

The membrane-based pervaporation process presents substantial promise for the challenging separation of azeotropic mixtures. However, the efficiency of conventional polymeric membranes in achieving this remains suboptimal. To tackle this issue, there has been notable attention directed towards the amalgamation of metal–organic frameworks (MOFs) with polymer matrices, giving rise to the creation of mixed matrix membranes (MMMs). In this study, for the first time, we integrated MOF-303 crystals into a chitosan (CS) matrix, thereby pioneering the development of MOF-303/CS MMMs designed for the separation of azeotropic mixtures of methanol/methyl tert-butyl ether (MTBE). By employing the spin-coating method, a thin and defect-free MOF-303/CS membrane layer was effectively deposited onto a porous substrate. The morphology and physiochemical attributes of the synthesized MOF-303 crystals and the subsequent MOF-303/CS MMMs were analyzed using techniques such as SEM, XRD, TGS, and FTIR. The separation data revealed a marked enhancement in flux and methanol permeance upon the introduction of MOF-303 crystals into the CS membrane, whereas the increase in MTBE flux and permeance was relatively few, resulting in an augmented methanol/MTBE separation factor and selectivity. The optimized MOF-303/CS MMM demonstrated outstanding and enduring separation efficacy, demonstrating a total flux of 173 g/m2·h and a methanol/MTBE separation factor of 209 at 40 °C for 10 wt% methanol-MTBE mixtures. Notably, this performance surpassed that of the pure CS membrane by nearly 1.6 times in total flux and 3.68 times in separation factor, respectively, underscoring its substantial potential in the efficient separation of azeotropic mixtures.