ZIF-8 sacrificial template strategy driven construction of nanovoids and performance optimization in nanofiltration membranes

Nanovoid-engineered TFC membranes fabricated via ZIF-8 sacrificial templates. • Acid etching creates maze-like wrinkled architectures with tubular nanovoids. • Optimized membrane shows 95% higher water permeance than conventional TFCs. • Maintained >97% divalent salt rejection and >99% organic dye rejection. • Controlled nanovoid engineering overcomes permeability-selectivity trade-off. Traditional thin-film composite (TFC) nanofiltration membranes face an inherent trade-off between water permeance and selectivity in water treatment applications. To overcome this challenge, this study proposes a nanostructure-mediated interfacial polymerization strategy using size-controlled zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (30-400 nm) as sacrificial templates to construct ordered nanovoid networks. By embedding ZIF-8 nanoparticles at the polyamide (PA)-polysulfone (PSf) interface and subsequently removing them via selective acid etching, a unique maze-like wrinkled architecture with tubular nanovoids is successfully generated. Systematic investigation reveals that the optimized membrane (TFC-200A, using 200 nm templates) achieves a remarkable pure water permeance of 15.7 L m −2  h −1 ·bar −1 -a 95% enhancement over conventional TFC membranes-while maintaining excellent selectivity, specifically >92% rejection for Na 2 SO 4 and >99% rejection for dyes. The enhanced performance arises from increased surface roughness, improved hydrophilicity, and laterally interconnected interfacial nanovoids that shorten water-transport pathways while preserving steric and electrostatic selectivity. Nanovoid continuity, rather than surface corrugation alone, governs permeance, with the effective template-size window limited by nanovoid discontinuity and PA-arch collapse. This controlled nanovoid engineering provides a highly effective pathway to break the permeance-selectivity trade-off, showing great promise for advanced wastewater treatment, dye removal, and desalination applications. Download: Download high-res image (338KB) Download: Download full-size image