Degradation Of RhB By Photoelectrocatalytic Fenton System Based On Nanostructured Electrodes

This paper illuminates the treatment of the wastewater through the physical, chemical or biologic technologies. And the paper reviews the advance oxidation processes (AOPs) in treating of wastewater in details. Photocatalytic oxidation of water contaminants is a new type of method for wastewater in recent years. It is widely and deeply studied by many people for its high photodegradation efficiency, none secondary pollution caused and the potential of utility of solar energy. Electrocatalytic oxidation is another one of advanced oxidation processes, which with the characteristic such as high utility of energy sources, simple equipment, low expenditure, easy to control automatic and none secondary pollution. So the development Photocatalytic and electrochemical oxidation in the treatment of waste water has been attracted considerable interest in recent study.The Fenton' regent was the combination of the Fe²⁺ and H₂O₂. The ability oxidation was caused the -OH produced by the reaction of Fe²⁺ and H₂O₂, The -OH can oxide the organic without selectivity. So it was used widely in the industry. But the cost of the Fenton reaction was larger than biologic technology. The large cost was binged by the consumption of Fe²⁺ and H₂O₂. We developed a novel Fenton system in this paper, in which the Fe²⁺ was produced by the anodic oxidation of iron foil in the anode and the H₂O₂ was generated in the cathode by deoxidation of H₂O in the cathodic cell. In the previous studies, we designed a new air electrode based on combining the ACF and Fe@Fe₂O₃ core-shell nanowires synthesized by the chemical reductive method (Fe@Fe₂O₃/ACF), and then used as an oxygen-fed gas diffusion electrode. The resulting Fe@Fe₂O₃/ACF composite electrode was examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). A novel electro-Fenton (E-Fenton) system was established with the resulting gas diffusion cathode, where hydrogen peroxide was electro-generated by the reduction of O₂ adsorbed on the cathode and iron ions were produced by the slow leakage of Fe@Fe₂O₃ nanowires, simultaneously. In addition, the impacted effect on the degradation of RhB by this novel E-Fenton systemn such as initial concentration and pH of RhB liquor, different catalysts amounts added, different Fe sources, reaction time and different voltage, were studies in details. Moreover, the possible mechanism of this E-Fenton was proposed: The H₂O was deoxidized into H₂O₂ and the Fe²⁺ was formed in the solution by the reaction of Fe⁰ with H₂O. The Fenton reaction was carried out by the Fe²⁺ and H₂O₂. The Fe³⁺ was deoxidized by the Fe⁰ and the electron of cathode. More importantly, the Fe@Fe₂O₃/ACF cathode was very stable and could be reused without losing its catalytic activity, suggesting its potential in the wastewater treatment.According to the research of photochemical, Photocatalytic, electrochemical technology in the treatment of waster water and our previous study of nanomaterial, we designed new double cell reaction equipment about photo-electro-chemical reaction. We used the "dip-coating" method to prepare the Bi₂WO+₆/ITO film electrode. In the new double cell reaction equipment, we studied the degradation of Rhodamine B (RhB) on the photoelectrocatalytic oxidation process in the different reaction condition, and studied the factor as initial concentration and pH of RhB liquor, applied potential and different electrolyte etc. We used the electrochemical method of EIS to prove the synergetic mechanism of Photocatalytic and electrochemical oxidation. The 600min circulation of the electrode was done to prove the stability of the Bi₂WO₆/ITO film electrode.As last, the synergetic effect of the photoelectrocatalytic oxidation of the Bi₂WO₆/ITO film electrode in the anodic cell and the E-Fenton oxidation of Fe@Fe₂O₃/ACF electrode in the cathodic cell. We calculate the efficiency of the electricity. The double cell has a higher efficiency of the electricity than the single one. The double is an effective method in using the electrocity in the electrochemical degradation. The photoelectrocatalytic and E-Fenton can reach the aim of "double cell, double effect".