Synthesis of Bi25FeO40 Nanoparticles with Oxygen Vacancies via Ball Milling for Fenton Oxidation of Tetracycline Hydrochloride and Reduction of Cr(VI)

Though heterogeneous Fenton-like reactions possess various characteristics such as a wide application range and mild reaction conditions, their reactivity is currently restricted by unsatisfactory H2O2 decomposition efficiency and low pH adaptation. Hence, Bi25FeO40 nanoparticles prepared via the mechanical ball-milling method (Bi25FeO40-B) with extensive oxygen vacancies possess high reactive oxygen species production performance by enhancing the H2O2 decomposition for tetracycline hydrochloride oxidation and Cr(VI) reduction. H2O2 decomposition efficiency can reach 55.3% in the presence of the Bi25FeO40-B catalyst, which is much higher than that of Bi25FeO40 prepared by the traditional hydrothermal method (23.8%). The Bi25FeO40-B/H2O2 heterogeneous Fenton system demonstrates efficient performance for simultaneous oxidation of tetracycline hydrochloride (TCH) and reduction of Cr(VI). It is capable of removing 75.2% of 50 mg/L TCH and 93.0% of 20 mg/L Cr(VI) at pHinitial = 7, respectively. Abundant oxygen vacancies on the surface of Bi25FeO40-B nanoparticles due to the nanometer size effect can accelerate the decomposition of H2O2 to promote the formation of reactive oxygen species for removing the target organic pollutants and reduction of Cr(VI). Consequently, this work provides a strategy for the preparation of oxygen-rich Bi25FeO40 catalysts for efficient degradation of contaminants and depicts the bright future of Fe-based metal oxides with oxygen vacancies on H2O2 activation in Fenton-like reactions.