Efficient photocatalytic removal of orange II by a Mn3O4–FeS2/Fe2O3 heterogeneous catalyst

Abstract

Elemental doping has been proven to be an effective strategy for increasing the catalytic activity and structural stability of Fenton catalysts. Therefore, this work reports that Mn-doped FeS2/Fe2O3 (Mn3O4–FeS2/Fe2O3) has excellent catalytic performance for the degradation of Orange II under simulated solar energy. Degradation experiment results showed that the sample with a manganese-iron molar ratio of 1:2 exhibited higher activity than others. The degradation rate of 20 mg/L OII reached 99.0% in 18 min under the conditions of 0.3 g/L Mn3O4–FeS2/Fe2O3, 5 mM H2O2 and pH = 2.8. In addition to, the Mn3O4–FeS2/Fe2O3 catalyst shows good reusability for Orange II and high activity for other dyes (MB, MG, Rh B and MO) under optimal conditions. Degradation mechanism study indicated that the heterogeneous Fenton reaction was promoted by retarding the recombination of photogenerated charge carriers and accelerating the cycle between Fe3+/Mn2+ and Fe2+/Mn3+, which improved photo-Fenton-like catalytic performance, resulting in the enhanced degradation of organic pollutant. Finally, a possible degradation pathway was proposed according to the results of liquid chromatography-mass spectrometry (LC-MS). In short, the catalyst has potential application value in wastewater treatment.