Polyamide thin film nanocomposite membrane containing polydopamine modified ZIF-8 for nanofiltration

Abstract In order to better disperse zeolitic imidazolate framework-8 (ZIF-8) in aqueous solution for thin film nanocomposite (TFN) membrane fabrication, hydrophilic ZIF-8 was prepared by polydopamine modification. After the interfacial polymerization (IP) reaction, PDA-ZIF-8 nanoparticles were evenly entrapped in the polyamide (PA) matrix. The as-obtained PA layer demonstrated better hydrophilicity, higher surface roughness, and less cross-linking degree. Therefore, the water permeability increased by 66 % compared to the thin film composite (TFC) membrane without nanofillers. Moreover, due to the improved compatibility of PDA-ZIF-8 as well as the stronger negatively charged membrane surface, the retention of SO42− was slightly enhanced, and the retention of rhodamine B was well maintained. The hydrophilic modification of ZIF-8 by PDA was a facile method to improve its compatibility with the PA polymer, and the resultant TFN membrane demonstrated elevated water permeability without compromising its selectivity.