PolyMOF interlayers modulated interfacial polymerization of ultra-thin nanofiltration membranes with efficient and stable desalination performance

Ultra-thin nanofiltration (NF) membranes exhibit excellent potential in the high-efficiency removal of ions due to their superior water permeability and selectivity. However, the stability of these membranes under pressure still poses a significant challenge. In this study, we have developed an innovative polyMOF interlayer using trimesoyl chloride (TMC) cross-linked UiO-66-NH2 (denoted as UiO-66-NH2-TMC) to bolster the construction of a pressure-resistant and ultra-thin polyamide (PA) membrane, achieving stable and high-permeance desalination performance. The introduced hydrophilic and structurally reinforced UiO-66-NH2-TMC interlayer with high pore density and narrow pore size distribution provides essential benefits: (1) it ensures a uniform distribution of amine monomers, which are critical for creating defect-free PA membranes; (2) it optimizes the diffusion of amine monomers, encouraging the formation of an ultra-thin PA membrane; and (3) it enhances the overall compatibility and structural support of the membrane, significantly improving pressure resistance. Consequently, our interlayer-modulated thin-film composite (i-TFC) membrane, with 13 nm thickness, demonstrates exceptional water permeance at 25 L m-2 h-1⋅bar-1 and maintains a high sodium sulfate (Na2SO4) rejection of 96%. Moreover, the i-TFC membranes exhibit stable performance under pressures ranging from 2 to 10 bar, display excellent long-term operational stability over 36 hours, and show an anti-fouling propensity with a notable flux recovery ratio of 81.5%. This research offers a novel approach to polyMOF interlayer application, carving a path toward designing and fabricating ultra-thin NF membranes with efficient and stable desalination properties.