Faculty of Environmental Science and Engineering Kunming University of Science and Technology Kunming 650500 China;
Faculty of Environmental Science and Engineering Kunming University of Science and Technology Kunming 650500 ChinaSchool of Environment Tsinghua University Beijing 100084 China;
State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China;
Conductive carbon black; PbO2 electrode; Metronidazole; Electrochemical oxidation; Box-Behnken design-response surface method;