FexP/biochar composites induced oxygen-driven Fenton-like reaction for sulfamethoxazole removal: Performance and reaction mechanism

Fe-based phosphide has shown tremendous potential for heterogeneous catalysis due to its superior activity. Herein, a series of FexP/biochar composites were successfully prepared through a simple pyrolysis process. Iron species (FeOOH) was pre-loaded on the surface of phosphorus-containing biomass (yeast), which was subsequently converted to FexP/biochar with the assistance of in-situ produced reducing gases (H-2, CO, PH3, etc.). When applied for typical antibiotic pollutant (sulfamethoxazole, SMX) removal, the optimal material (FexP/BC-5) performed well with a 99% removal efficiency in 30 min via the synergistic effects of adsorption and degradation by activation of dissolved oxygen (DO). Reactive oxygen species, including H2O2, center dot OH, center dot O-2(-) and O-1(2), were generated in FexP/BC-5/DO system by charge transfer and Fenton-like reaction. FexP/BC-5 was applicable in a broad pH range from 3.0 to 9.0 and exhibited good reusability in five recycle runs after regeneration. Moreover, the primary reactions in SMX degradation process were discussed based on identified intermediates by liquid chromatography-mass spectrometry (LC-MS). This work not only develops a simple approach to construct iron phosphides/biochar using green and sustainable phosphorus source but also bring new insights for environmental pollutants remediation by oxygen activation.