Investigation on microwave absorbing properties of loaded MnFe2O4 and degradation of Reactive Brilliant Red X-3B

• MnFe2O4-SiC, MnFe2O4-TiO2 and MnFe2O4-diatomite were first to be synthesized.
• The microwave absorbing properties of the catalysts were calculated by Matlab 7.0.
• Fast decolorization and high TOC removal of Reactive Brilliant Red X-3B could occur with MnFe2O4-SiC under MW irradiation.
• The toxicities of the azo-dyes during the degradation with MnFe2O4-SiC were lower enough.
• MnFe2O4-SiC was of practical use in the wastewater treatment.

Four nanocomposite catalysts namely MnFe2O4, MnFe2O4-SiC, MnFe2O4-TiO2 and MnFe2O4-diatomite, were synthesized and characterized by X-ray diffraction (XRD) and N2 adsorption (BET specific surface area). Measurements of the catalysts’ complex permittivity and permeability in the microwave (MW) frequency range of 0.5–18 GHz showed MnFe2O4-SiC composites to be the best MW absorbers. The surface temperature of MnFe2O4-SiC (1450 °C) under MW was higher compared to those of the other three catalysts, indicating that silicon carbide (SiC) was an effective support. MW-assisted experiments demonstrated that the degradation of RBR X-3B with MnFe2O4-SiC reached 92%, achieved 70% of TOC removal and exhibited lower toxicity with 5 min MW irradiation, proving MnFe2O4-SiC to be an excellent microwave catalyst. These findings are important regarding the development of efficient sorbents that are effective microwave absorbers as well as catalysts of rapid degradation of pollutants.

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