Forward Osmosis Membranes Fabricated on Microfilter Support with Sacrificial Zeolitic Imidazolate Framework Interlayer

Water desalination is essential to address global water scarcity, and forward osmosis (FO) has emerged as a promising method due to its low energy demand. However, FO membrane performance is limited by internal concentration polarization and defects in the polyamide (PA) active layer when using highly porous supports. In this work, PA thin-film composite membranes were fabricated on microfiltration membrane supports modified with a sacrificial zeolitic imidazolate framework (ZIF-67) interlayer. The interlayer reduced pore size and provided a uniform reaction interface for controlled interfacial polymerization while being easily removed by water after PA formation. By tuning cobalt and imidazole concentrations, we tailored the interlayer density and its effect on PA morphology and FO performance. The optimized membrane achieved a water flux of 25.5 LMH with a reverse salt flux of 4.27 gMH (active layer facing feed). Notably, by increasing the support pore size to 450 nm, the water flux further increased to 40.1 LMH. These findings highlight the effectiveness of a removable ZIF-67 interlayer in engineering high-performance FO membranes.