Superhydrophilic and antibacterial zwitterionic polyamide nanofiltration membranes for antibiotics separation

Superhydrophilic and antibacterial zwitterionic polyamide thin film composite nanofiltration membranes (ZTFCMs) with excellent water permeability and antibiotics selectivity were prepared through the interfacial polymerization of N-aminoethyl piperazine propane sulfonate (AEPPS) monomer with trimesoyl chloride (TMC) monomer on top of polysulfone ultrafiltration supporting membranes (PSF-UF). Chemical structures of the ZTFCMs were evaluated by attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and element analysis (EA), with membrane microstructures and hydrophilicity being examined by microscopies and water contact angle, respectively. Superhydrophilic ZTFCMs were obtained with more AEPPS content on membrane surface, and they show excellent water permeability coupled with high erythromycin (ERY) retention. For example, the water permeability and retention to ERY of the ZTFCM (AEPPS aqueous concentration is 3.0 wt%) are 8.4 L m−2 h−1 bar−1 and 96.5% (applied pressure is 6 bar), respectively. In addition, the ERY concentration of the mixed feed increases exponentially from 100.0 to 350.7 mg L−1 with a treatment capacity of 61.6 L m−2 h−1 during 7.25 h continuous concentration operation. Furthermore, ZTFCMs show a stable and good separation performance during a long-time filtration process of 168 h and exhibit an exceptional antibacterial property assessed by Escherichia coli adhesion.