[Degradation of AO7 with Magnetic Fe 3 O 4 -CuO Heterogeneous Catalyzed Sodium Percarbonate System].

Magnetically recyclable FeO-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 FeO-CuO was studied. The effects of FeO-CuO catalyst loading, SPC concentration, pH value, and common chloride ions on AO7 degradation in the FeO-CuO/SPC system were evaluated. The main reaction mechanism of AO7 degradation was analyzed. The results show that FeO-CuO could effectively activate SPC to degrade AO7 and the reaction was accelerated with the increase of FeO-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 FeO-CuO showed excellent stability owing to the high catalytic activity remaining after 4 cycles of repeated use. The FeO-CuO/SPC system achieved a high mineralization rate in the process of decolorization of AO7.