UiO-66-NH2 decorated EVOH nanofiber substrate induces the formation of high-performance Janus PA nanofiltration membrane

High-quality polyamide (PA) nanofiltration (NF) membrane with excellent selectivity and permeability is of great research significant because of their high practical application value, especially for the precise separation of divalent and monovalent ions, such as Mg 2+ and Li + . Herein, UiO-66-NH 2 nanoparticles (NPs) decorated ethylene vinyl alcohol copolymer (EVOH) nanofiber substrate (M-NFM) was utilized to construct high-quality Janus NF membrane through interfacial polymerization (IP) reaction using polyethyleneimine (PEI) and piperazine (PIP) as aqueous phase monomers and trimesoyl chloride (TMC) as organic phase monomers. The incorporation of UiO-66-NH 2 NPs significantly influenced the hydrophilicity, surface morphology, and pore structure of the substrate, thereby enhancing the properties of the resulting NF. Optimally prepared membranes demonstrated improved separation performance, permeability, stability, and antifouling characteristics compared to the unmodified substrate. Notably, at a Mg 2+ /Li + ratio of 30, the resultant NF membrane achieved a separation factor (S Mg 2+ /Li + ) of 28.4 and a salt permeation flux of 156.8   L·m -2 ·h -1 ·MPa -1 . Additionally, the membrane exhibited over 98% rejection rates for FeCl 3 , CuSO 4 , CaCl 2 , MgSO 4 , MgCl 2 and Na 2 SO 4 with fluxes exceeding 150   L·m -2 ·h -1 ·MPa -1 , highlighting its effectiveness in rejecting multivalent ions. This research presents a simpler and more reliable approach to the fabrication of high-quality Janus PA NF membrane, offering promising potential for industrial-scale applications.