ZIF-8 ligand exchange-driven fabrication of high-permeability reverse osmosis membranes for desalination and small molecule pollutant removal

To address the growing global challenge of water scarcity, developing high-performance reverse osmosis (RO) membranes for desalination and water purification is essential. However, conventional polyamide (PA) thin-film composite (TFC) membranes are limited by the trade-off between permeability and selectivity, as well as limited rejection of small-molecular contaminants. In this study, we report a novel high-permeability thin-film nanocomposite (TFN) RO membrane by tuning the hydrophilicity of a zeolitic imidazolate framework-8 (ZIF-8) interlayer to achieve synergistic enhancement in both desalination and micropollutant removal. Specifically, a ZIF-8 interlayer was in situ grown on a hyperbranched PA-UIO-66-NH 2 support, followed by partial ligand exchange with 5,6-dimethylbenzimidazole (Hdmbim) to reduce its hydrophilicity. This modification facilitated the diffusion of m-phenylenediamine (MPD) monomers, enabling the formation of a highly cross-linked PA selective layer (h-TFN) with angstrom-scale water transport channels. The optimized h-TFN membrane exhibited a water permeability of 5.40 L·m −2 ·h −1 ·bar −1 , 2.94 times that of the control TFC membrane, while maintaining high NaCl rejection (98.35 %). Moreover, it achieved 96.06 ± 0.18 % rejection for micropollutants such as heptyl paraben (HP). These results surpass the permeability–selectivity limitations of existing membranes and demonstrate a promising strategy for the design of advanced RO membranes capable of efficient desalination and micropollutant removal.