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

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. •The degradation of Orange II by Mn3O4–FeS2/Fe2O3 attained to 99.0% in 18 min.•Both .•OH and •O2− played important roles in the degradation process.•The photo-Fenton-like catalytic performance of the Mn3O4–FeS2/Fe2O3 catalyst was enhanced.•The catalyst maintained excellent reusability for Orange II and high activity for other dyes.