Organic carbon modified Fe3O4/schwertmannite for heterogeneous Fenton reaction featuring synergistic in-situ H2O2 generation and activation

Abstract Spontaneous generation of H2O2 and activation in heterogeneous Fenton is a promising technology for waste-water treatment. Here organic carbon modified Fe3O4/schwertmannite (Fe3O4/Sch/OC) by introducing Fe3O4 in the Acidithiobacillus ferrooxidans-driven Fe2+ oxidation process to give catalysts. In-situ H2O2 could be generated via Fe3O4/Sch/OC-driven oxygen reduction reaction (ORR), moreover, the in-situ H2O2 was disintegrated to produce •OH in Fe3O4/Sch/OC-driven Fenton reaction to degrade the methylene blue (MB). The catalysts were characterized by XRD, SEM, BET and XPS spectroscopy. Oxygen-containing functional groups (e.g., C = O, –COOH, –OH) on Fe3O4/Sch/OC surface could provide more active sites for the adsorption and reduction of O2. The carbon-modification promoted both the selectivity of 2e− ORR and Fe2+ content of catalyst. Thus, Fe3O4/Sch/OC exhibited a higher H2O2 selectivity (~65%) and MB degradation efficiency (~81%) than Sch, Fe3O4, or Fe3O4/Sch. In addition, in-situ H2O2 could be produced at a wide initial pH range (3–9). The degradation pathways of MB were also proposed based on theoretically calculated and LC-MS data. The finding opens up a new way for developing a cost-effective Sch-based catalyst for producing in-situ H2O2 and degrading pollutants.