Polyamide Nanofiltration Membranes from Emulsion-Mediated Interfacial Polymerization: Fid-Bau Portal

Polyamide Nanofiltration Membranes from Emulsion-Mediated Interfacial Polymerization

Liang, Yuanzhe / Teng, Xiangxiu / Chen, Rui / Zhu, Yuzhang / Jin, Jian / Lin, Shihong

Fabrication of nanofiltration (NF) membranes using interfacial polymerization (IP) continues to receive tremendous interest in research and development due to the broad applications of NF in water treatment, wastewater reuse, and industrial separations. Many approaches have been explored to enhance the performance of NF membranes by regulating the IP process. Among these approaches, the use of surfactants has shown strong potential due to its low cost and compatibility with existing infrastructure for membrane fabrication. While the different roles of the surfactants have been increasingly elucidated in recent years, little is known for the role of emulsion formation in the IP process. In this study, we investigate the impacts of nonionic, emulsifying surfactants on the formation, properties, and performance of the polyamide NF membranes. Two surfactants were compared, including the hydrophilic Tween 80, which is an oil-in-water (o/w) emulsifier added in the aqueous solution of piperazine, and the lipophilic Span 80, which is a water-in-oil (w/o) emulsifier added in the hexane solution of trimesoyl chloride. Our results illustrate the effects of emulsions as “vehicles” to facilitate monomer transfer and as “microreactors” for providing additional and distributed interfaces for IP. Depending on whether the surfactants are o/w or w/o emulsifiers, the resulting membranes have unique physicochemical properties and NF performance. In both cases, the addition of nonionic surfactants at low-to-moderate concentrations results in smaller pore sizes and a narrower pore size distribution. Overall, this study provides important insights into how the IP process and the resulting NF membranes are influenced by the formation of emulsions.