A novel multi-components hierarchical porous composite prepared from solid wastes for benzohydroxamic acid degradation

In this study, a novel carbon-wrapped-iron hierarchical porous catalyst (Fe/C-Mn800) was prepared from electrolytic manganese residue (EMR) and sewage sludge (SS), which showed outstanding degradation ability toward benzohydroxamic acid (BHA, nearly 90 % was removed within 60 min) with low metal leaching rate. Mechanism exploration found transition metal ions (Fe and Mn) can serve as electron acceptors and facilitate the generation of persistent free radicals (PFRs). These transition metal ions and PFRs mainly participated in the single-electron pathway via activating PMS to generate a large amount of reactive oxygen species (ROS). While the electron negative graphitic N and C=O groups not only improve the electronegatively of catalyst, but also acted as the electron sacrificers to favor the elec-tron transfer and directly oxidized the absorbed BHA through the ternary activated outer-sphere com-plexes. Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) analysis further demonstrated the crucial role of pre-adsorption during the degradation process. This work provided a deep insight into the degra-dation mechanism of metal/carbon composite and promising opportunity widened the horizon of the high-value utilization of EMR and SS. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, a novel Fe/C-Mn800 catalyst was prepared from EMR and SS, which exhibited excellent degradation ability towards BHA with low metal leaching rate. Mechanism exploration revealed that Fe and Mn served as electron acceptors and facilitated the generation of PFRs, leading to the production of ROS via the activation of PMS. The graphitic N and C=O groups on the catalyst improved its electronegativity and acted as electron sacrificers for electron transfer and direct oxidation of absorbed BHA.