Complexes of cupric ion and tartaric acid enhanced calcium peroxide Fenton-like reaction for metronidazole degradation

To surmount the obstacles of traditional Fenton method and synchronously utilize Cu2+ and polyphenol in water, an improved Fenton-like reaction applying calcium peroxide (CaO2 ) as H2O2 source and regulating by the complex of Cu2+ -tartaric acid (TA, a representative of polyphenol) was constructed. A typical antibiotic, metronidazole (MTZ) could be effectively eliminated by the Cu2+ /TA/CaO2 system, and the optimized parameters were as follows: 0.1 mmol/L Cu2+ , 2 mmol/L TA, 2 mmol/L CaO2 , and initial pH 5. UV spectrum confirmed the formation of Cu2+ -TA complex, which promoted the Cu2+ /Cu+ circulation through decreasing the Cu2+ /Cu+ couple redox potential, which further enhanced the H2O2 decomposition and the formation of reactive species. Hydroxyl radical was dominant for MTZ degradation, followed by oxygen and superoxide radical. The degradation intermediates of MTZ were detected and their evolution way was speculated. Furthermore, the ternary process showed a wide pH tolerance (3-8) for removing MTZ and broad applicability for eliminating other dyes and antibiotics. This work provided a reference for Cu-based Fenton-like strategy for organic wastewater settlement. (c) 2024 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.