Biogenic silver nanoparticles-modified forward osmosis membranes with mitigated internal concentration polarization and enhanced antibacterial properties

Thin-film composite forward osmosis (TFC-FO) membranes show the potential to be applied in water treatment applications. However, the TFC-FO membrane performance was limited by internal concentration polarization (ICP) and membrane fouling. In this study, a well-functioning TFC-FO membrane was produced by embedding biogenic silver nanoparticles (BioAg) into the polysulfone (PSf) substrate of a FO membrane. Effects of BioAg on membrane structure, filtration performance, antifouling, and antibacterial properties of the as-prepared FO membranes were examined. Results indicated that BioAg-modified FO membranes achieved improved surface hydrophilicity, higher porosity, and mitigated ICP, resulting in 2.5-4.4 times higher water flux than the pristine FO membranes. The BioAg-modified FO membrane also showed significantly improved antifouling and antibacterial ability. Moreover, the release velocity of silver nanoparticles in FO membranes was significantly slowed down by the construction of the polyamide layer. After 30 days of immersion in an aqueous solution, 96.5% of silver was retained in the optimized BioAg-modified FO membrane. The study offers an effective approach to simultaneously mitigate ICP and enhance the antifouling property of TFC-FO membranes through substrate modification.