Use of aqueous polyol monomer for superior dye separation performance and high chlorine resistance of thin-film composite polyester nanofiltration membranes

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

“…Since the discovery of nanofiltration (NF) membranes in the 1970s, polyamide (PA) membranes based on diamine monomers [i.e., piperazine (PIP) or m -phenylenediamine (MPD)] and TMC have been widely applied for water softening, drinking water purification, and wastewater reclamation due to their excellent separation performance. − However, the attack of the nitrogen atom in amide bonds by free chlorine generated during pretreatment for biofouling prevention or membrane cleaning processes poses a challenge to the material stability and longevity of PA membranes. − In contrast, due to the absence of chlorine attack sites in the cross-linking groups, polyester (PE) membranes can have excellent chlorine resistance. , In previous studies, polyester films based on many different monomers (such as cyclodextrin, pentaerythritol, erythritol, glucose, POPs, etc.) have maintained performance stability in long-term harsh chlorine environments. − Furthermore, the PE membranes containing abundant hydroxyl groups usually possess high surface hydrophilicity, thus exhibiting excellent antifouling ability. − Therefore, PE membranes are considered to have great potential advantages in water treatment applications.…”

“…Studies of PA membranes have demonstrated that utilization of different monomers with distinct diffusivity and reactivity can result in PA membranes with different properties by affecting the membrane formation process. − Likewise, differences in membrane properties and separation performance caused by aqueous monomer molecular size had been compared in some previous studies of polyester membranes. , However, the effect of different monomer reactivity caused by variations in the density of hydroxyl groups (e.g., the ratio of carbon atoms to hydroxyl groups) and the difference in the reactivity of primary and secondary hydroxyl groups of the monomers was neglected. − Until now, a comprehensive understanding of the effect of monomer activity and functional group activity on PE membrane formation and thus the membrane performance has not been achieved, which hinders the rational design and advantage exploitation of PE membranes.…”