Red mud-based heterogeneous catalyst for hydrothermal resource-based degradation of norfloxacin in pharmaceutical wastewater by hydrogen peroxide

Red mud (RM) was used as a catalyst for the hydrothermal degradation of antibiotics in simulated pharmaceutical wastewater by H2O2 to produce formic acid. Formic acid could be adopted as hydrogen storage, conforming to carbon neutral strategy. When 10 mL norfloxacin (NOR) solution was used at 40 mg/L, the optimal reaction conditions were 0.02 g RM activated at 100 °C, 0.2 mL added H2O2, as well as the reaction time and temperature of 0.5 h and 90 °C, leading to NOR degradation rate of 69.26 % and a formic acid yield of 58.36 % (selectivity: 87.56 %). The RM catalyst presented good activity and stability in reuse. In this study, phase composition and structure of RM catalyst before and after the reaction were comprehensively characterized, and kinetic model was established. Moreover, the key intermediate pathway of NOR degradation was identified by LC-MS. Under the concept of "treating waste with waste", these results suggested that wastewater-treatment technology of solid waste (Red Mud) was "Fenton-like" catalyst for resource-based degrading high-ecotoxicity antibiotic pollutants in pharmaceutical wastewater. This process could support environmental protection and green development of the pharmaceutical industry, together with hazardous waste-recycling treatment. In short, this research provides a theoretical basis for the subsequent engineering resource treatment of pharmaceutical wastewater.