Surface grafted zwitterions modulate the microstructure of polyamide separation layer to achieve efficient antibiotic desalination

Anti-fouling polyamide nanofiltration (NF) membranes for antibiotics desalination by employing commercial glycerophosphocholine (GPC) as a distinctive surface modifier via in situ surface grafting modification. By leveraging the hydroxyl groups in GPC, we have successfully anchored small GPC molecules onto the nascent polyamide membrane surface. This innovative process, compared to the control membrane without GPC grafting (designated as GPC-0), has effectively tailored the membrane surface micro-morphology, hydrophilicity, electronegativity, and size of free volume elements, showcasing a three-dimensional characteristic and zwitterionic phosphocholine moieties. The optimized GPC-2 membrane exhibits a remarkable pure water permeance of 25.0 L m−2 h−1 bar−1 and a superior rejection (>95 %) towards various antibiotics. When subjected to a tetracycline hydrochloride (TC)/NaCl mixture solution as a model separation object, the GPC-2 membrane demonstrates rejections of 98.2 % for TC and 10.5 % for NaCl, indicating efficient separation of antibiotics/monovalent salt. Furthermore, the GPC-2 membrane showcases robust antifouling performance against both positively and negatively charged organic foulants. More importantly, beyond the exceptional fouling resistance, the antibiotics desalination performance of GPC-2 membrane surpasses that of most literature-reported and commercial membranes, which enables GPC-2 membrane as a promising candidate for applications in saline antibiotics fermentation broth and the recycling of wastewater resources.