Enhanced generation of hydroxyl radicals on well-crystallized molybdenum trioxide/nano-graphite anode with sesame cake-like structure for degradation of bio-refractory antibiotic

Anodic electro-catalysis oxidation is a highly effective way to solve the pollution problem of antibiotics in wastewater and receiving water bodies. In this study, for the first time, molybdenum trioxide/Nano-graphite (MoO3/Nano-G) composites are synthesized as anodic catalysts by a surfactant-assisted solvothermal method followed by low-temperature calcination. The effects of the proportion of MoO3 to Nano-G (10, 30 and 50%) on the properties of composites are investigated through structural characterizations and electrochemical measurements. Results indicate that MoO3(30)/Nano-G electrode displays the electro-catalysis degradation efficiency of 99.9% towards ceftazidime, which is much higher than those of Nano-G (46.7%) and dimensionally stable anode (69.2%). The degradation mechanism for ceftazidime is studied by investigating the yields and kinds of active species. Results show that all of the OH, O2− and H2O2 are responsible for the electro-catalytic degradation process, and the produced OH radicals are the major active species for ceftazidime degradation. The synergistic effects between MoO3 and Nano-G greatly contribute to the activation of H2O molecules to produce OH, meanwhile the special sesame cake-like structure facilitates to the exposure of contaminants to OH on active sites to enhance the degradation efficiency. These results suggest that MoO3/Nano-G electrodes can be considered as the promising catalysts for treating bio-refractory organic wastewater.