Enhanced H2O2 utilization efficiency in Fenton-like system for degradation of emerging contaminants: Oxygen vacancy-mediated activation of O2

Hydrogen peroxide (H2O2) is the most commonly used oxidant in advanced oxidation processes for emerging organic contaminant degradation. However, the activation of H2O2 to generate reactive oxygen species is always accompanied by O2 generation resulting in H2O2 waste. Here, we prepare a Ti doped Mn3O4/Fe3O4 ternary catalyst (Ti-Mn3O4/Fe3O4) to create abundant oxygen vacancies (OVs), which yields electron delocalization impacts on enhancing the electrical conductivity, accelerating the activation of O2 to produce H2O2. In Ti-Mn3O4/Fe3O4/H2O2 system, OVs-mediated O2/O2•-/H2O2 redox cycles trigger the activation of locally generated O2, boost the regeneration of O2•- and on site produce H2O2 for replenishment. This leads to a 100% removal of tiamulin in 30 min at an unprecedented H2O2 utilization efficiency of 96.0%, which is 24 folds higher than that with Fe3O4/H2O2. Importantly, further integration of Ti-Mn3O4/Fe3O4 catalysts into membrane filtration achieved high rejections of tiamulin (> 83.9%) from real surface water during a continuous 12-h operation, demonstrating broad pH adaptability, excellent catalytic stability and leaching resistance. This work demonstrates a feasible strategy for developing OVs-rich catalysts for improving H2O2 utilization efficiency via activation of locally generated oxygen during the Haber-Weiss reaction.