A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton: high activity, wide pH range and catalytic mechanism

A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton (EF) was synthesized by a facile precipitation approach via sintering products of oxalate co-precipitation. This obtained NiFe2O4/Fe2O3 catalyst was easily separated via an external magnetic field and was used as a heterogeneous electro-Fenton catalyst for rhodamine B (RhB, a target pollutant) degradation. Characteristics of NiFe2O4/Fe2O3 catalyst were assessed using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Barrett-Emmett-Teller (BET), respectively. SEM results revealed that the proposed NiFe2O4/Fe2O3 was charcoal-shaped with the size in the range of 0.5-5 mu m. Experiment results show that the EF process with the proposed catalyst could work in a wide pH range from 3 to 9. Under optimized conditions, estimated 90% RhB degradation was achieved in 60 min under the following conditions: 0.6 g/L NiFe2O4/Fe2O3, pH 3. Radical scavengers and electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was , accounting for RhB degradation in EF. Moreover, according to our research on interfacial reaction, was mainly generated from the homogenous Fenton reaction rather than the surface Fenton reaction, stimulating by the dissolved Fe2+, Fe3+ and Ni2+ from catalyst. The reusability of NiFe2O4/Fe2O3 catalyst was evaluated for recycling the same catalyst for 5 runs. In conclusion, the facile fabrication NiFe2O4/Fe2O3 catalyst shows great potential in wastewater treatment with promising activity. [GRAPHICS] .