Bimetallic CuFe2O4 photocatalytic activates persistent free radicals and accelerates electron transfer in biochar: Efficient degradation of tetracycline.

Water pollution has become an urgent issue around the world, antibiotic residues in water result in health or environmental problems worldwide. In order to address the key issues of low catalytic efficiency, poor stability, and low visible light utilization in the current photocatalytic treatment of recalcitrant organic pollutants in water, bimetallic CuFe2O4/ABC was successfully obtained from extracted Astragalus residue and used for degradation of tetracycline under visible light. First, the bimetallic active centers (Fe and Cu) enhanced the separation of charge carriers under visible light. Then, Fe and Cu active centers activated and enhanced the production of persistent free radicals (PFRs) in biochar. Fe2+ and Cu+ in the bimetallic active centers transferred e- to O2 to promote the formation of •O2-, which efficiently degraded tetracycline (94.89 %) without H2O2. Notably, the persistent free radicals (PFRs) served as intrinsic electron reservoirs. By donating electrons derived from oxidized C-C bonds to Fe/Cu centers.