Experimental Studies On The Electro-Fenton Degradation Of Model Azo Dye Wastewater

Azo dyes wastewater is not only high chromatic,strong noxious,but also difficult to degrade and easy to discompose to carcinogenic aromatic amine under deoxidization condition.So,azo dyes wastewater must be treated urgently.However, many kinds of problems exist in the conventional wastewater treatment methods, which can not completely mineralize the organic dyes,the decolorization efficiency is not high,and the recycling of water is difficult to solve.As a new wastewater treatment technology, the electro-Fenton method,which includes strong free radical oxidation and electro-deoxidation,can degrade of organic matters efficiently,and it becomes a hot water treatment research in the field gradually.In this thesis,methyl orange solution,which had typical structure of azo dyes, was studied by electro-Fenton method.The best experimental conditions were obtained by the analysis of the influences of operating parameters including electrode potential, Fe2+ concentration,electrolyte Na2SO4 concentration and electrolytic time on the removal rate of methyl orange.Under the best conditions,the effect on the degradation of methyl orange by the surfactant SDS was studied,when it presented in the solution;then the effect of cathode materials on the degradation of methyl orange by replacing the cathode materials was studied,and at last the degradation mechanism of methyl orange was discussed through the analyse of the UV-Visible spectrum and high performance liquid chromatogram.The experimental results showed that,at the best conditions of the initial concentration of methyl orange of 0.05mmol/L,the pH value of 3,the air volume of 0.1m3/h,Na2SO4 and FeSO4 concentrations of 14.08mmol/L,0.27mmol/L,and the electrode potential of 5V,the decolorization rate of methyl orange could exceed 98% when electrolyzing 90min,and the degradation process of methyl orange accorded with first order kinetic equation.When methyl orange coexisted with the surfactant SDS,if the SDS concentration was lower than the critical micelle concentration,the two oxidative degradation reacted simultaneously,and the degradation of methyl orange was limited;The limitation was more significant as the concentration of SDS increased,but the limitation was gradually reduced if the concentration of SDS was higher than the critical micelle concentration.Through the comparison of four different cathodes in electro-Fenton degradation of methyl orange,we could see that,the decoloration value of methyl orange,which could reached 99.22%,was the highest with the silver-gilt steel wire cathode,and then the titanizing steel wire cathode,the steel wire cathode and the plumbaginous cathode in turn,which were 95.98%,93.08% and 90.92% respectively.And this result provided a new idea for the future selection of cathode materials in electro-Fenton method.