Degradation of AO7 with Magnetic Fe3O4-CuO Heterogeneous Catalyzed Sodium Percarbonate System

Abstract

Magnetically recyclable Fe3O4-CuO was synthesized by a one-step hydrothermal method and characterized by scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD). The degradation of azo dye acid orange 7 (AO7) by percarbonate (SPC) activated with Fe3O4-CuO was studied. The effects of Fe3O4-CuO catalyst loading, SPC concentration, pH value, and common chloride ions on AO7 degradation in the Fe3O4-CuO/SPC system were evaluated. The main reaction mechanism of AO7 degradation was analyzed. The results show that Fe3O4-CuO could effectively activate SPC to degrade AO7 and the reaction was accelerated with the increase of Fe3O4-CuO dosage. The increase of SPC dosage was favorable for the degradation of AO7, but excessive SPC dosage inhibited the degradation of AO7. Common ions (e.g., Cl-) in dye wastewater could promote the degradation of AO7, and the degradation rate increased with increasing concentration of Cl-. The reaction mainly occurred on the surface of the catalyst, and·OH was identified as the main active species for the degradation of AO7. The catalyst Fe3O4-CuO showed excellent stability owing to the high catalytic activity remaining after 4 cycles of repeated use. The Fe3O4-CuO/SPC system achieved a high mineralization rate in the process of decolorization of AO7.