The role of microporous metal-organic frameworks in thin-film nanocomposite membranes for nanofiltration

Endowed with amendable pore apertures and chemistries as well as customized topologies, metal-organic frameworks (MOFs) have displayed a promise to improve the separation efficacy of thin-film nanocomposite (TFN) membranes. In this study, the microporous MOF-801 nanoparticles (NPs) with robust water stability were synthesized using a green synthesis approach at room temperature. Subsequently, the MOF-801 NPs were positioned atop the polysulfone (PSf) membrane support via vacuum-assisted filtration, followed by interfacial polymerization to construct TFN membranes. A wide array of characterizations was conducted to analyze the physicochemical properties and morphological characteristics of the MOF-801 and the modified polyamide (PA) membranes. Results revealed the successful synthesis of MOF-801 nanocrystals with abundant micropores and a high crystallinity. The incorporation of MOF-801 NPs to the PA layer was found to induce substantial improvements in surface hydrophilicity and roughness as well as thinner PA layers, which are favorable for rapid water molecule transport. The water permeability of TFN membranes presented a notable 98% increment compared to the thin-film composite (TFC) membrane with only a small compromise for salt rejection. This work underscores the promising potential of nanoporous and acid-base stable MOF-801 as an efficient nanofiller for constructing nanofiltration membranes with admirable performance.