Pioneering integration of bimetallic Fe2O3-Mn2O3 nanoparticles into polyamide nanofiltration membranes for enhanced antibiotic wastewater treatment

High-concentration antibiotic wastewater treatment presents a formidable challenge, and polyamide nanofiltration membranes have emerged as a promising solution to this challenge. However, efficient membranes and involved separation mechanisms are still being explored. This study endeavors to fill this knowledge gap by pioneering the integration of bimetallic Fe 2 O 3 -Mn 2 O 3 nanoparticles into the polyamide selective layer, resulting in the development of a thin-film nanocomposite nanofiltration membrane. The membrane showed impressive water permeance (10.5 L m −2 h −1 bar −1 ) and a remarkable Na 2 SO 4 rejection (97.1 %). Three antibiotics (tetracycline, clindamycin phosphate, and tobramycin) with similar molecular weights but varying molecular conformation and charge were treated using these membranes. All three antibiotics exhibited substantial rejection rates: tetracycline at 97.1 %, clindamycin phosphate at 95.0 %, and tobramycin at 87.0 %. It was discerned that the separation efficacy was intimately tethered to both antibiotics’ molecular conformation and charge. Antibiotics possessing a rigid structural archetype, exemplified by tetracycline, attained highest rejection rates. Clindamycin phosphate, with its flexible molecular structure and negative charge, demonstrated a superior rejection rate to tobramycin, which has a positive charge. This differential performance is ascribed to the charge exclusion effect. The insights gained from this work hold significant implications for the practical application of membrane separation methods in treating antibiotic wastewater.