Enhancing nanofiltration membrane performance for emerging organic contaminants (EOCs) removal via PEG-mediated monomer diffusion

Polyethylene glycol (PEG), a versatile non-ionic surfactant with excellent biocompatibility and robust chemical stability, offers significant potential for the precise regulation of interfacial polymerization (IP). In this study, PEG was introduced into the aqueous phase as an additive to modulate the interfacial diffusion behavior of piperazine (PIP). By systematically optimizing its molecular weight, concentration, and terminal group parameters, a polyamide (PA) active layer with a smaller and more uniformly distributed pore structure was successfully constructed. This optimized architecture effectively strengthened both the size exclusion and charge repulsion mechanisms of the nanofiltration (NF) membrane. Consequently, the optimal MP 1000 -10 membrane exhibited highly competitive NF performance, achieving an impressive Na 2 SO 4 rejection of 98.0% and a high water permeance of 11.5 L m −2  h −1 bar −1 . More importantly, tailoring the PEG terminal groups facilitated targeted control over the pore size and surface charge properties, significantly enhancing the removal of structurally and physicochemically diverse emerging organic contaminants (EOCs). Across a broad set of experimental parameters, PEG modification consistently delivers improved separation performance for membranes. With excellent stability, high efficiency and economic feasibility, this strategy provides solid technical and theoretical support for developing advanced separation membranes targeting high-efficiency EOCs removal.