A green in-situ synthesis of biochar-supported Fe0/Cu0 bimetallic catalyst for the efficient oxidation antibacterial in water: Performance and mechanism analysis

The zero-valent transition bimetallic system has an excellent performance in antibacterial, but its worse stability, dispersibility and complex preparation process affect its application in water treatment. In this study, we synthesized a magnetic biochar-supported Fe-0/Cu-0 (BC@Fe-0/Cu-0) using waste reed straw, iron salts and copper salts as raw materials by a green and facile one-step carbothermal reduction for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) inactivation. Results indicated that the introduce of biochar not only improved the dispersion of metal particles, but also promote the successful generation of low valence ferric (Fe-0) and low valence copper (Cu-0), which were critical for antibacterial. In the antibacterial experiments, BC@Fe-0/Cu-0 achieved 100 % inactivation of E. coli and 97.05 % inactivation of S. aureus within an hour without adding additional substances or energy. Importantly, the BC@Fe-0/Cu-0 also displayed splendid antibacterial effect against harmful microorganisms in authentic water matrix and showed sound reusability and stability, with a >88 % antibacterial efficiency after 8 cycles. According to the Electron Spin Resonance (ESR) results, center dot OH and center dot O-2(-) were the major reactive oxygen species (ROS), generating from the reaction between low valence metal (Fe-0 and Cu-0) and O-2/H2O. This study provides a novel approach to prepare a prospective composite with efficient antibacterial for water treatment.