Efficient degradation of semi-coking wastewater in three-dimensional electro-Fenton by CuFeO heterocatalyst.

Semi-coking wastewater contains a rich source of toxic and refractory compounds. Three-dimensional electro-Fenton (3D/EF) process used CuFeO as heterocatalyst and activated carbon (AC) as particle electrode was constructed for degrading semi-coking wastewater greenly and efficiently. CuFeO nanoparticles were prepared by coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy disperse spectroscopy (EDS). Factors like dosage of CuFeO, applied voltage, dosage of AC and pH, which effect COD removal rate of semi-coking waste water were studied. The results showed that COD removal rate reached to 80.9% by 3D/EF process at the optimum condition: 4 V, 0.3 g of CuFeO, 1 g of AC and pH = 3. Trapping experiment suggesting that hydroxyl radical (•OH) is the main active radical. The surface composition and chemical states of the fresh and used CuFeO were analyzed by XPS indicating that Fe, Cu, and O species are involved into the 3D/EF process. Additionally, anode oxidation and the adsorption and catalysis of AC are also contributed to the bleaching of semi-coking waste water. The possible mechanisms of 3D/EF for degrading semi-coking waste water by CuFeO heterocatalyst were proposed.