Facile fabrication of polyamide-polyester nanofiltration membranes regulated by ionic liquids for efficient antibiotic desalination

The effective separation and purification of antibiotics from fermentation broth is challenged by the presence of salts such as NaCl. When these salts accumulate to high concentrations, they can interfere with antibiotic recovery and stability. Nanofiltration membranes provide an energy-efficient approach for antibiotic desalination, but improving selectivity while maintaining high permeability remains critical. In this study, a novel NF membrane was fabricated via interfacial polymerization process using piperazine and choline hydrogen tartrate (CHT), an ionic liquid , as aqueous monomers, reacting with trimesoyl chloride. The hydroxyl-rich CHT functioned as both a co -monomer and a polymerization regulator, leading to the formation of a thinner, looser polyamide–polyester selective layer with enhanced hydrophilicity. The optimal membrane exhibited a water permeance of 14.2 L·m −2 ·h −1 ·bar −1 (twice that of the control membrane) while achieving >99 % antibiotic rejection and maintaining low NaCl rejection (~0.5 %). The antibiotics/NaCl selectivity was significantly improved, with a tetracycline/NaCl selectivity of 111, a 1.6-fold increase over the control membrane. Furthermore, multi-stage filtration experiments (pre-concentration, diafiltration, and post-concentration) successfully demonstrated the potential for antibiotic enrichment while ensuring high-purity separation. This study provides a novel and effective NF membrane fabrication strategy, offering valuable insights into the development of high-performance antibiotic desalination membranes.