Fabrication of highly selective PEBA mixed matrix membranes by incorporating metal-organic framework MIL-53 (Al) for the pervaporation separation of pyridine-water mixture

Pyridine is generally found in the effluents from the synthesis of paints, rubber chemicals, vitamins, and pesticides. This study focused on improving the pervaporation (PV) performance of polyether block-amide (PEBA-2533) membranes cast on polyvinylidene fluoride (PVDF) substrate, by incorporating the MIL-53 (Al) particles to prepare mixed matrix membranes (MMMs) for pyridine separation from the aqueous solution. MIL-53 (Al) has a larger aperture size (8.5 Å) than the molecular size of the pyridine (6.0 Å), which could allow pyridine molecules to efficiently pass through its channels. The coadjacent MIL-53 particles created relatively continuous permeation pathways for the penetrants in the MMMs, which substantially enhanced the separation performance. Impressively, the resultant MMMs displayed superior pyridine separation performance at complex conditions. At 65 °C and 0.5 wt% pyridine aqueous solution, the separation factor and pyridine flux of PEBA/PVDF membrane were 17.3 and 143.5 g m−2 h−1, which were improved using MIL-53@PEBA/PVDF MMMs to 48.1 and 226.9 g m−2 h−1, respectively. Owing to the enhanced pyridine affinity, hydrophobic property, and thermal robustness, the resultant MMMs overcame the inherent trade-off between selectivity and permeability, and also displayed the promising long-term stability. These findings may provide valuable insights for developing novel MMMs with superior separation performance.