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

Hydrogen peroxide (H 2 O 2 ) is the most commonly used oxidant in advanced oxidation processes for emerging organic contaminant degradation. However, the activation of H 2 O 2 to generate reactive oxygen species is always accompanied by O 2 generation resulting in H 2 O 2 waste. Here, we prepare a Ti doped Mn 3 O 4 /Fe 3 O 4 ternary catalyst (Ti-Mn 3 O 4 /Fe 3 O 4 ) to create abundant oxygen vacancies (OVs), which yields electron delocalization impacts on enhancing the electrical conductivity, accelerating the activation of O 2 to produce H 2 O 2 . In Ti-Mn 3 O 4 /Fe 3 O 4 /H 2 O 2 system, OVs-mediated O 2 /O 2 •− /H 2 O 2 redox cycles trigger the activation of locally generated O 2 , boost the regeneration of O 2 •− and on site produce H 2 O 2 for replenishment. This leads to a 100% removal of tiamulin in 30 min at an unprecedented H 2 O 2 utilization efficiency of 96.0%, which is 24 folds higher than that with Fe 3 O 4 /H 2 O 2 . Importantly, further integration of Ti-Mn 3 O 4 /Fe 3 O 4 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 H 2 O 2 utilization efficiency via activation of locally generated oxygen during the Haber-Weiss reaction.