High-permeability and anti-fouling nanofiltration membranes decorated by asymmetric organic phosphate

Aiming at the two challenging bottlenecks of “trade-off effect” and “membrane fouling” that limit the development of nanofiltration (NF) membranes, this work developed a high-performance NF membrane based on the modification by an asymmetric hydrophilic zoledronic acid (ZA). ZA plays multiple roles: (1) the self-restrictive diffusion effect of piperazine (PIP)/ZA obtained from the reaction of PIP and ZA resulted in smooth membrane surface; (2) the imidazolyl on ZA uninvolved in interfacial polymerization (IP) led to enlarged polyamide network pores and provided more solvent tunnels; (3) all groups of ZA improved the membrane hydrophilicity; (4) the electronegative phosphate groups made a significant contribution to the strong membrane surface electronegativity. As a result, the ZA-modified membrane exhibited nearly five times higher permeability than that of traditional NF membranes, accompanied by perfect selectivity of SO₄²⁻ and Cl⁻ as well as the outstanding anti-fouling property, indicating its enormous application prospect in water treatment.