Engineering dual-reinforced antibacterial and anti-fouling ultrafiltration membrane by in-situ synthesising super-dispersion and high-activity silver nanoparticles (AgNPs)

•Super-dispersion and high-activity AgNPs were in-situ formed within the membrane.•AgNP-modified membrane showed dual-reinforced antibacterial and anti-fouling.•The i-Ag-UF membrane exhibited a 59% permeability improvement than the control.•Antibacterial rate of i-Ag-UF membrane against E. coli and S. aureus was > 99.99 %.•AgNP-modified membrane showed efficiency and stability in actual water treatment. Membrane fouling, especially biofouling, would result in frequent cleaning and shorten membrane lifespan. Fabricating Ag nanoparticle (AgNP)-modified ultrafiltration (UF) membranes provided an innovative solution for in-situ membrane biofouling control. Inspired by the tongue’s taste generation mechanism, this study adopted sodium citrate and AgNO3 to in-situ synthesize AgNP-modified UF (i-Ag-UF) membrane with the characteristics of ‘super-dispersion and high-activity’ AgNPs, enhancing the antimicrobial and anti-fouling properties. Compared to the control, a perpendicular and rich macroporous finger-type structure was engineered in the i-Ag-UF membrane, which contributed to a 59 % permeability improvement (421.7 L m-2h−1 bar−1), thereby improving filtration efficiency and reducing operational costs. This enhancement was attributed to the in-situ synthesis of small-sized, super-dispersed AgNPs, improving compatibility and stability with membrane matrix, and enhancing resistance to interlayer shear stress during phase inversion. Furthermore, the i-Ag-UF membrane surface exhibited the highest hydrophilicity and surface polarity, which formed a hydration layer and increased pollutant repulsion, thereby greatly enhancing its anti-fouling performance and achieving a higher flux recovery rate of 98.64 %. Such enhancement could significantly improve the economic benefits and sustainability of the UF process. The i-Ag-UF membrane demonstrated exceptionally high antibacterial efficiency (>99.99 %), attributed to the widely dispersed, high-activity AgNPs with numerous exposure points. In addition, the i-Ag-UF membrane, with only 2.5 wt% Ag release after 50 days owing to the entanglement between AgNPs and polymer chains. These findings provide new insights into the fabrication of highly antibacterial and anti-fouling dual-enhanced UF membranes.