Preparation Of Effective Gas Diffusion Electrode And Its Application To The Degradation Of Fenpyroximate-containing Wastewater

Refractory organic wastewater can bring about great harm. Traditional biochemical treatment methods are often difficult to deal with such sewage. In recent years, many researchers at home and abroad have dedicated to improve degradation rate of toxic ingredients inside with stable structure, which is not easily decomposed by microorganisms.Large amount of fenpyroximate has been used to control agricultural insect pests, recently. The damaging effects of fenpyroximate-containing wastewater on fish and shellfish can result in a reduction in fisheries production; spoil the ecosystem of water body and present great risk to human health. Thus, it is necessary to develop effective technique to deal with the fenpyroximate-containing wastewater.Hydrogen peroxide is one of the most popular non-selective oxidizing agents. It is an environmental friendly chemical since it leaves no hazardous residuals but carbon dioxide and water after reaction. Furthermore, the most common environmental application of H2O2is the Fenton’s reagent, an aqueous mixture of H2O2and Fe2+. Under an acidic condition, the reaction between H2O2and Fe2+generates hydroxyl radicals that are strong enough to non-selectively oxidize most organic.In this paper, the orthogonal experimental design was applied to the optimization of the parameters affecting catalyst preparation. Take hydrogen peroxide production of a certain period of time as the index of the test. Finally, the best conditions were determined as follows: CA/Mn+=1.6, pH=10, calcination temperature=800℃.The lanthanum nitrate perovskite structure catalyst was prepared by the sol-gel method and used for making C/PTFE gas-diffusion electrode, when mixed with modified graphite and other raw materials. At last, the result indicated that active site of oxygen reduction grew in number; the BET and pole volumetric were enlarged.When were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM), it turned out that the LaNiO3catalyst prepared had a pure crystalling phase; the GDEs prepared had a rich-pore structure, a good gas diffusion property, and a great theoretical yield as employed to the situ electro-synthesis hydrogen peroxide. Under the optimal electrolytic conditions for the effective production of hydrogen peroxide, the quantity of H2O2amounted to116.9mg/L.When gas diffusion electrode was used as cathode, and graphite electrode as anode, effect of different electrolysis factors on the removal rate of fenpyroximate was studied. When the electrolysis conditions were:C (Na2SO4)=0.05mol/L, Current intensity=0.3A, aeration rate=150L/min, C (Fe2+)=1.0mmol/L, pH=3, the removal rate of fenpyroximate reached74%, with the process of electrochemical degradation following the first order reaction kinetics model.Providing a new method of the effective production of H2O2in acid conditions, this research enriched the range of applications and content of the difficult degradable organics’ electrochemical oxidation.