Cu inanchored MnO/carbonaceous frameworks trigger peroxymonosulfate activation for enrofloxacin degradation: ROS generation and pollutant attacking processes

Abstract

Despite Fluoroquinolone antibiotics (FQs) removal in peroxymonosulfate (PMS) activation have been widely researched and the outstanding degradation performance have been gained, the detailed processes by which reactive oxygen species attack pollutants have not been adequately studied. In this study, a Cu/MnO catalyst is anchored onto carbonaceous frameworks using a one-step calcination method for investigation. Benefiting from the sp2 unsaturated carbon as well as the synergistic effect between Cu2+/Cu+/Cu and Mn3+/Mn2+ bimetallic redox electron pairs, the prepared Cu/MnO anchored on carbonaceous frameworks catalyst (4CuMn/C-800) material possesses excellent enrofloxacin (ENR) removal performance, where 85.52 % of ENR is degraded in 80 mins, and maintains relatively high catalysis performance even in the various reaction conditions (reaction pH, reaction temperature, existing anions etc.). The analysis reveals the 1O2 and •O2-, as the dominate ROS, continuously attack the specific active sites of ENR molecules until they are mineralized. In detail, the generated •O2- mainly attacks the piperazine ring, while the formed 1O2 assaults the quinolone group of ENR. By combining density functional theory (DFT) calculations with LC-MS analysis, we propose four distinct pathways for ENR degradation in the 4CuMn/C-800/PMS system. In summary, this study offers a novel and practical approach to design metal/metal oxide/carbon catalysts and enhances our understanding of the mechanisms behind ROS-driven PMS activation.