Ethylene-glycol-regulated nanofiltration membranes for micropollutant removal and mineral preservation in drinking water treatment

Nanofiltration (NF) for advanced drinking-water treatment has long been constrained by the need to remove contaminants while preserving beneficial mineral ions in health-oriented drinking water. Herein, an ethylene-glycol (EG)-regulated aqueous microenvironment was introduced to tailor the interfacial polymerization process. EG-mediated hydrogen bonding and modified interfacial thermodynamics jointly regulated piperazine diffusion, interfacial transport, and polymerization kinetics, producing polyamide NF membranes with enhanced negative charge surface density and a more uniform effective pore structure. Compared with the pristine membrane, the EG-20 membrane exhibited a thinner, more hydrophilic, and more negatively charged selective layer, together with a narrower pore-size distribution. The optimized EG-20 membrane achieved a permeance of 23.6 L m −2  h −1 bar −1 while maintaining Na 2 SO 4 rejection above 95.5%. In the treatment of natural surface water, dissolved organic matter removal reached approximately 92.1%, while partial passage of beneficial mineral ions was maintained, enabling effective organic contaminant removal with mineral preservation for health-oriented drinking water treatment. Moreover, high rejection of PFAS and antibiotics was maintained, mainly because steric exclusion and enhanced electrostatic repulsion compensated for the moderately enlarged effective pores. In addition, the membrane showed improved antifouling performance, as enhanced surface hydration and electrostatic repulsion reduced foulant adhesion and suppressed irreversible fouling. Overall, this microenvironment-regulation strategy provides a feasible route for developing NF membranes that integrate effective contaminant control, mineral preservation, and stable operation.