One-Step Surface Grafting Method for Preparing Zwitterionic Nanofiltation Membrane via In Situ Introduction of Initiator in Interfacial Polymerization

In this work, a polyamide membrane was first prepared via in situ introduction of a surface-initiated atom transfer radical polymerization (SI-ATRP) initiator in interfacial polymerization. Then, a zwitterionic membrane was obtained by SI-ATRP grafting of sulfobetaine methacrylate on a polyamide membrane. The prepared membranes were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy, indicating the successful grafting of zwitterions on polyamide membranes. Pure water permeability of the optimized zwitterionic membrane was up to 16.8 L m–2 h–1 bar–1, 2.9 times as high as that of the polyamide membrane with similar Na2SO4 rejection. The NaCl rejection of the membrane after grafting for 1 h was only 17.2%, much lower than that with a polyamide membrane, which was sought for separation of monovalent salts/neutral organics. The membrane also showed excellent antifouling properties when three categories of usual pollutants were chosen as feed solution. The one-step SI-ATRP method for preparing zwitterionic membranes with high permeability was facile and convenient, which has promising applications in desalination and food separation processes.