Inorganic salt regulated zwitterionic nanofiltration membranes for antibiotic/monovalent salt separation

Zwitterionic nanofiltration membranes (ZNFMs) are conducive to achieve efficient antibiotic/monovalent salt separation. However, preparation of ZNFMs through interfacial polymerization is limited by electrostatic interaction between zwitterions. In this study, inorganic salts were applied to regulate reactions in interfacial polymerization, such as interfacial reaction and thermal cross-linking reaction. The electrostatic interaction between zwitterions was broken by the inorganic salts to promote cross-linking of zwitterionic polyamide networks. Therefore, an intact and ultrathin separation layer was formed on substrates. The obtained ZNFMs exhibited a high permeance of 21.6 L m−2 h−1 bar−1, while the rejections for erythromycin (ERY) and NaCl were 97.5% and 8.5%, respectively. Moreover, the ZNFMs also had an exceptional anti-fouling property, which showed a great potential in antibiotic/monovalent salt separation.