Mechanistic study on distinct roles of antibiotics in constructing high-performance antifouling nanofiltration membranes via in-situ and surface modifications

Polyamide (PA) nanofiltration (NF) membranes inherently struggle with the permeability-selectivity trade-off and membrane fouling. This study deploys antibiotics, specifically aminoglycoside (gentamicin, streptomycin, amikacin, kanamycin) and quinolone (ciprofloxacin), to construct PA NF membranes through in-situ or surface modification strategy. For the first time, we systematically investigated the influences of antibiotic molecular structures and modification pathways on membrane properties and performances. By correlating antibiotic chemical structures with modification efficacy, we disclose that aminoglycosides, owing to their high reactivity and multiple reactive sites, outperform quinolones in tailoring membrane properties and performance. In-situ modification regulates amine monomer diffusion kinetics and alters polymerization reaction mechanism, yielding thinner, more permeable PA layers with tailored bulk properties. In contrast, surface modification enables higher antibiotic loading and primarily adjusts surface characteristics, endowing the membrane with superior antifouling performance. NF membranes engineered by both approaches significantly surpass the pristine NF membrane in separation performance and fouling resistance: in-situ modified membranes achieve an exceptional water flux (224 % increasement), while surface-modified membranes exhibit superior antibiotic/NaCl selectivity (162) for pharmaceutical wastewater treatment coupled with outstanding fouling resistance against both organic and microbial foulants. This work establishes antibiotic-mediated membrane engineering, offering a scalable solution to address permeability-selectivity-fouling trilemma and advancing sustainable water purification technologies.