Thin Film Composite Nanofiltration Membrane Mediated by MOF Interlayer with Novel MOF Templating Technique for Water Treatment

Thin-film nanocomposite (TFN) membranes often suffer from inconsistent nanoparticles (NPs) distribution and poor interaction with the polymer matrix, which can lead to defects and reduced performance. Meanwhile, achieving enhanced water permeance without sacrificing rejection efficiency remains a major challenge in the development of Thin-film composite (TFC) nanofiltration (NF) membranes with enhanced performance. In this study, we present a novel and facile solvent evaporation technique for positioning the ZIF-67 metal–organic framework (MOF) as a sacrificial interlayer between piperazine (PIP) and trimesoyl chloride (TMC) during interfacial polymerization (IP). This approach enables precise MOF placement, mitigating material loss, and attaining uniform distribution, thus producing a defect-free polyamide (PA) layer. Upon exposure to water, the MOF interlayer undergoes self-degradation, generating nanovoids that enhance water transport pathways, reduce the PA layer thickness, and increase membrane hydrophilicity. Four different MOF loadings were evaluated, and the membrane containing 0.03 wt % MOF, referred to as TFNi-0.003, exhibited the best overall performance. This optimized NF membrane achieved a normalized water flux (NWF) of 25.5 L·m–2·h–1·bar–1 (LMHB), leading to a 2-fold improvement over the control membrane, while ensuring reliable Na2SO4 rejection at 95.6%. These findings demonstrated the potential of MOF-templated interlayer engineering as an effective strategy for developing next-generation NF membranes.