Lecithin-assisted fabrication of reverse osmosis membranes with enhanced fouling and chlorine resistance

초록

The advancement of polyamide (PA) reverse osmosis (RO) membranes is limited by the performance-durability trade-off. Although surfactant-assisted interfacial polymerization (IP) has proven effective at improving both the separation and antifouling performance of such membranes, its efficacy in enhancing their chlorine resistance remains unknown. Moreover, most available surfactants are petroleum-derived, raising sustainability and toxicity concerns. Herein, we demonstrate that the addition of a specific lecithin (LEC) component (i.e., L alpha-phosphatidylcholine), a bio-derived zwitterionic surfactant, to the IP aqueous medium produces highperformance, fouling- and chlorine-resistant RO thin-film composite (TFC) membranes. LEC addition enhances substrate wettability and accelerates amine monomer diffusion presumably by inducing Marangoni instability, forming a more permselective PA layer. Furthermore, the embedment of LEC in the PA matrix imparts zwitterionic characteristics to the membrane, generating a robust surface hydration layer that effectively suppresses the surface accessibility of both foulants and oxidants. Consequently, the optimized LEC-added (TFC-LEC) membrane demonstrates excellent RO performance, outperforming many commercial benchmarks and labfabricated RO membranes. Compared with its pristine counterpart, the TFC-LEC membrane also exhibits superior chlorine tolerance and fouling resistance against both biological and organic foulants, while ensuring longterm stability. This study provides a facile and sustainable platform for tailoring the performance and durability of membranes.

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