Cuprammonium cellulose nanomembranes for sustainable antibiotic removal from water

A novel environmentally-friendly conjugate structural membrane, composed of cuprammonium cellulose (CC), polyethylene oxide (PEO), and polyacrylonitrile (PAN), was fabricated using conjugate electrospinning. Adsorption of ciprofloxacin (CIP) from water was achieved using the conjugated membrane (CC-PAN). By combining PEO and PAN with CC, the membrane's mechanical strength was significantly enhanced, and notably improved its selective adsorption capability for antibiotics in both organic and inorganic systems. The CC-PAN membrane demonstrated high adsorption capacity for ciprofloxacin (CIP), reaching a maximum of 70.7 mg/g. The adsorption ability of CC-PAN towards CIP remained unaffected even at low CIP concentrations of 5 ppm in tap water. The adsorption mechanisms of CC-PAN onto CIP were extensively investigated by combining adsorption kinetics, thermodynamics, and isotherms. Spectroscopic methods were further employed to explore the interactions at various pH levels from 2 to 10. The adsorption capacity revealed a clear pH dependence. Specifically, at pH < 6.4, electrostatic attraction, interactions between electron donors and acceptors (likely hydrogen bonding), were the most predominant interactions. Furthermore, CC-PAN exhibited excellent stability, retaining 68 mg/g of its original adsorption capability during five successive adsorption-desorption repetitions. In addition to CIP, CC-PAN could also effectively remove tetracycline (TC) and trimethoprim (TMP). Based on these vital characteristics, CC-PAN demonstrates potential as an effective material for removing antibiotics from water through adsorption.