Rapid Cr(VI) reduction in aqueous solution using a novel microwave-based treatment with MoS2-MnFe2O4 composite

Microwave-induced catalytic system has been widely used in oxidation of organic pollutants, but no report focuses on heavy metal reduction. To expand the application field of microwave-induced catalytic system, MoS 2 decorated MnFe 2 O 4 was synthesized by hydrothermal method and employed for the reduction of Cr(VI) in microwave-induced catalytic system. The morphologies, chemical compositions, and optical properties of the synthesized catalysts were investigated using SEM, XRD, FT-IR and XPS. The MoS 2 -MnFe 2 O 4 samples exhibited significantly enhanced microwave-catalytic performance for Cr(VI) reduction compared to pristine MoS 2 and MnFe 2 O 4 , among which, the MoS 2 -MnFe 2 O 4 (10 wt%) sample was most suitable for Cr(VI) reduction in aqueous solution. 85.8% of Cr(VI) removal was obtained in 16 min in the present of MoS 2 -MnFe 2 O 4 . The effect of catalyst dosage, initial pH and microwave output on Cr(VI) reduction were investigated. Mechanism of Cr(VI) removal was investigated by radical quenching experiments. The enhanced microwave-catalytic activity of MoS 2 -MnFe 2 O 4 may be owing to the fact that MoS 2 can act as an electron acceptor to suppress the recombination of microwave-excited electron-holes. These results showed that microwave-induced catalytic reduction system is promising in Cr(VI) decontamination in aqueous solution.