Improving properties of thin film nanocomposite membrane via temperature-controlled interfacial polymerization for nanofiltration process

Research on the effect of interfacial polymerization (IP) temperature during polyamide layer synthesis is lacking, especially for thin film nanocomposite (TFN) nanofiltration membrane. Typically, polyamide composite membranes are fabricated at room temperature, ignoring the potential impact of reaction temperature. In this work, we varied the organic solvent temperature to study its impacts on the properties of TFN membrane containing surface-functionalized graphene oxide (GO) for nanofiltration process. A more cross-linked and rougher polyamide layer could be formed at 55 °C due to higher reaction kinetics and more volatile IP reaction. This membrane exhibited excellent Na2SO4 rejection (99 %) with a water-salt permselectivity ratio of 11.0, i.e., >2 folds compared to the commercial membrane (4.88). However, its rougher surface resulted in a higher protein adhesion even with the enhanced antifouling property brought by GO hydrophilicity. In comparison, the TFN membrane developed at 0 °C displayed very thin yet smooth polyamide layer, resulting in a higher water flux and improved antifouling performance. Furthermore, the TFN membrane demonstrated stable filtration performance for 12 h and GO nanosheets were still well accommodated within selective layer after testing. Overall, the improved filtration performance and reduced protein adsorption demonstrated the feasibility of IP temperature variation in TFN membrane fabrication.