A High-Permeance Nanofiltration Membrane via Complementary Interface Engineering for Enhanced Selectivity between Mineral Salts and Emerging Pollutants

Nanofiltration (NF) membranes with high water permeance, superior emerging pollutant (EP) retention, and selective mineral salt passage are highly desirable for high-quality drinking water treatment, yet challenging due to the selectivity−permeance trade-off. Herein, a polyamide-based NF membrane was engineered via a complementary interface strategy involving (2-hydroxypropyl)-β-cyclodextrin (CD) doping and secondary sulfonamidation with sulfuryl chloride (SC). The resulting CD-PA-SC membrane exhibited excellent water permeance (26.9 L m−2 h−1 bar−1, 3.5- and 2.4-fold higher than NF 90 and NF 270), while maintaining high rejection for five typical EPs with diverse properties and selectively allowing the passage of dietary mineral ions. Time-of-flight secondary ion mass spectrometry analysis, transition state theory, MD simulation, and DFT calculations revealed that CD-PA-SC’s thinner and more hydrophilic active layer promotes water permeance; its more negative surface charge facilitates mineral ion passage; and the tailored pore size, together with the CD-enhanced intrapore diffusion resistance, ensures enhanced broad-spectrum EP rejection. Thus, CD-PA-SC combines high efficiency, a low carbon footprint, and healthy water production, with promising applications in secondary water supply and point-of-use purifiers. This complementary dual-step modification strategy offers new insights into designing NF membranes for multiobjective separations in advanced drinking water treatment.