New insights on microwave induced rapid degradation of methyl orange based on the joint reaction with acceleration effect between electron hopping and Fe2+-H2O2 reaction of NiFeMnO4 nanocomposites

An innovative approach using thermal sensitizer NiFeMinO(4) under microwave (MW)-H2O2 condition was proposed to remove organic pollutant of model wastewater. The removal efficiency of 30.0 mg/L methyl orange for NiFeMnO4 under MW-H2O2 condition in 6.0 min reached up to 96.5%, which is larger than that for activated carbon under same MW-Fenton condition. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) method, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that the NiFeMnO4 power with an average size of less than 40 nm and specific surface areas (19.87 m(2)/g) had a spinel-type cubic structure, in which Ni2+, Mn3+, Mn4+, Fe3+ and Fe2+ occupied the octahedral sites of NiFeMnO4 lattice. The studies of low-temperature thermal degradation, microwave induced oxidation, microwave combining with H2O2 catalytic behavior and effect of active species for NiFeMnO4 indicated that the feasibility to MW-NiFeMnO4-H2O2 route had been successfully verified and joint reaction with acceleration effect of the direct decomposition by MW hot spots, the MW hot spots accelerated electron-hole excitation and Fe2+-H2O2 reaction was responsible for the degradation of methyl orange in NiFeMinO(4)-MW-H2O2 system.