Zwitterionic triethanolamine-grafted nanofiltration membranes for sustainable antibiotic recovery

With the increasing emphasis on sustainable development, membrane technology has extended from wastewater treatment to the recovery of high-value bioproducts (e.g., antibiotics), offering a high-efficiency, low-energy alternative to conventional solvent extraction and crystallization. In this work, we grafted zwitterionic triethanolamine (ZTEA) on the polyamide (PA) to construct a PA-polyester nanofiltration membrane (PA-ZTEA) for efficient antibiotic recovery. The zwitterionic structure increased membrane hydrophilicity and enlarged pore size. The modified PA-ZTEA membrane demonstrated approximately twice the pure water permeance (20.3 L m⁻² h⁻¹ bar⁻¹) compared to the pristine PA membrane while maintaining over 98 % erythromycin (ERY) rejection. The optimal membrane exhibited outstanding NaCl/ERY separation factor (58.4), while it achieved an ERY concentration factor of 2.95 in the continuous operation in a simulated fermentation broth, significantly outperforming the pristine PA membrane (1.63). Moreover, the PA-ZTEA membrane exhibited exceptional antifouling properties against proteins, polysaccharides, and surfactants (e.g., 94.0 % sodium dodecyl sulfate flux recovery ratio versus 84.5 % for the PA control), owing to its hydration layer that inhibited foulant adsorption. This work establishes an effective strategy for enhancing antibiotic recovery from fermentation broths, addressing key challenges in desalination efficiency.