Ultra-effective integrated technologies for water disinfection with a novel 0D-2D-3D nanostructured rGO-AgNP/Bi₂Fe₄O₉ composite

Emerging technologies for water disinfection is being developed to reduce waterborne disease efficiently. Herein, we report a novel bactericidal technology incorporating 0D-2D-3D nanostructured rGO-Ag/Bi₂Fe₄O₉ (BFOA-G) composites which exhibited ultra-effective disinfection efficacies towards Gram-negative E. coli and P. aeruginosa, and Gram-positive S. aureus. Owing to the synergistic action among BFO (Bi₂Fe₄O₉), AgNPs (Ag nanoparticles) and rGO (reduced graphene oxide) within BFOA-G, the H₂O₂/Vis/BFOA-G system (Vis, 420 < λ < 630 nm) showed remarkable bactericidal performance of approaching 100% efficacy (≥6 logs) of E. coli in 20 min with the inhibition of Ag⁺ leaching (usually achieving 3 logs of bacterial reduction around 1–4 h in photocatalytic disinfection). This system is defined as “integrated technology” that involves varied disinfection processes/mechanisms of rGO-assisted Ag⁺ release, Ag-assisted Fenton reaction, Ag/rGO co-assisted photocatalysis and Ag-assisted photo-Fenton oxidation. This novel BFOA-G was produced by incorporating the in-situ synthesized 0D-3D Ag-BFO (AgNP size of 5–20 nm) with 2D rGO via a facile evaporation process at 75 °C. The bacterial cell membrane damage caused by reactive oxygen species (ROSs) was verified by staining the cells using Live/Dead Baclight Kit. This study provides new insights into potential of nanostructured composites for developing innovative water disinfection technologies.