Fabrication of Dense Polyester Nanofiltration Membranes with Superior Fouling and Chlorine Resistance: Effect of Polyol Monomer Properties and Underlying Mechanisms

Polyester (PE) membranes have attracted a great deal of attention due to their notable chlorine resistance and antifouling ability. Despite the fact that various polyhydroxy molecules have been used as aqueous monomers, few have been capable of attaining a PE membrane with a high separation ability of small molecular organics, and relevant membrane formation mechanisms are still unclear. In this study, three relatively dense polyester membranes were obtained by optimizing reaction conditions, using erythritol, xylitol, and isomalt, all of which showed satisfying separation capacities and the potential to be used for applications requiring high rejections of small molecular organics, such as drinking water treatment. Comprehensive characterization and molecular simulation were conducted to elucidate the process of formation of PE membranes prepared with different polyol monomers. It was demonstrated that the physicochemical properties and separation performance of PE membranes were jointly affected by the molecular size of polyols as well as their hydroxyl density and activity. Compared with the commercial NF270 and lab-made polyamide membranes, all three PE membranes showed application advantages, including better chlorine resistance and antifouling performance. This study provides references for the rational selection of monomers and performance optimization in the development of high-performance PE membranes.