L-ascorbic acid-modulated interfacial polymerization for high-flux nanofiltration membranes toward PFAS removal and natural water purification

l -ascorbic acid regulates the interfacial polymerization microenvironment. • A thinner polyamide layer with enhanced negative charge and a more uniform pore structure was obtained. • AA-3 increases water permeance by 38% while maintaining approximately 96% Na 2 SO 4 rejection. • AA-3 achieves 84.7–99.8% rejection for 17 PFAS under the tested conditions. The global occurrence of per- and polyfluoroalkyl substances (PFAS) poses a serious threat to aquatic ecosystems and human health, thereby necessitating the development of advanced water purification technologies. In this study, l -ascorbic acid (AA) was introduced as a multifunctional regulator into the interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride, providing a green and sustainable route for fabricating high-flux nanofiltration (NF) membranes. Owing to its abundant hydroxyl groups, AA alters the aqueous-phase reaction environment and reduces PIP transport toward the water/organic interface, thereby moderating the IP process and promoting the formation of a thinner and more uniform nanonodular PA layer. Among the tested membranes, AA-3 was selected as the optimized membrane because it provided the most favorable overall balance between water permeance and selectivity, achieving a water permeance of 21.0 L m −2  h −1 bar −1 while maintaining 95.9% Na 2 SO 4 rejection. When applied to treat river water affected by saltwater intrusion, the membrane demonstrated effective purification performance while allowing partial passage of Ca 2+ and Mg 2+ ions. Furthermore, the membrane exhibited excellent removal efficiencies for 17 PFAS compounds, with rejection ranging from 84.7 to 99.8%. These results demonstrate that AA-regulated IP offers a promising strategy for developing next-generation environmentally friendly NF membranes for efficient PFAS control and drinking water protection. Download: Download high-res image (290KB) Download: Download full-size image