Controllable synthesis of mesoporous manganese oxide microsphere efficient for photo-Fenton-like removal of fluoroquinolone antibiotics

Abstract

Controllable synthesis of mesoporous manganese oxide (MnOx) microsphere is successfully achieved using a soft-template P123 assisted method. The as-obtained MnOx materials are highly efficient and versatile to remove the category of fluoroquinolone antibiotics (i.e., ofloxacin, ciprofloxacin, enrofloxacin and levofloxacin) using peroxymonosulfate (PMS) as the oxidant under UV or simulated sunlight irradiation. The mesoporous Mn3O4 microsphere prepared in the presence of 2 g P123 (P2-Mn3O4) exhibits the superior catalytic activity with almost perfect degradation for the fluoroquinolone antibiotics in 10 min under UV irradiation. Moreover, under simulated sunlight irradiation, 74.5% of ofloxacin, 79.4% of ciprofloxacin, 72.3% of enrofloxacin and 81.9% of levofloxacin can be degraded by P2-Mn3O4 in 10 min. Besides, the P2-Mn3O4 catalyst maintains stable without the obvious deactivation of catalytic activity or structural change after several successive runs, and slight leaching of Mn ions is observed. The ESR spectra further document that SO4−, OH, O2− and 1O2 radicals are prominent in the decomposition process of antibiotic molecules. In the end, the reaction kinetic and rational degradation pathway are also investigated and proposed.