Study On The Application Of Photoelectric Fenton In Wastewater Treatment

In recent years,with the rapid development of petro,pesticide and dyes and other industrial,the type and quantity of refractory organic compounds is growing with increasingly serious harm,which has become the focus of control of water pollution.In order to achieve the effective degradation of organic pollutants,hydroxyl radical ·OH-based on advanced oxidation technologies has emerged and photoelectric Fenton is a hot topic.Most of the organic pollutants can be effectively degraded,such as chlorophenols,aromatic amines.Compared with other advanced oxidation technology,it has the advantages of simple operation,low energy consumption,less pollution,etc and overcome shortcomings: low quantum efficiency of traditional photo Fenton and catalyst regeneration of electric Fenton.In the paper,firstly,phosphotungstovanadic heteropoly acids were synthesized with hydrothermal method and characterized by UV-vis,elemental analysis,IR,TG,X-ray diffraction et al.The results show that it belongs to Keggin structure of 1:12 type and its exact formula is H₅PW₁₀V₂O₄₀·5.76H₂O.Fe₅(PW₁₀V₂O₄₀)₃（FePWV）,Al₅(PW₁₀V₂O₄₀)₃（AlPWV）,Cu₅(PW₁₀V₂O₄₀)₂（CuPWV）were synthesized by H₅PW₁₀V₂O₄₀·5.76H₂O doped with Fe,Al and Cu.Secondly,the performance of FePWV in photo Fenton was studied in the degradation of methyl orange pollution and the influences of factors,such as catalyst dosage,initial concentration of methyl orange,pH,H₂O₂ and different doped metal,were discussed.The optimum conditions are that the dosage of FePWV was 4 μmol/L,the initial concentration of methyl orange was 10 mg/L,pH was 6,while the degradation rate of methyl orange and the removal efficiency of TOC was about 83% and 46%,respectively.Degradation rate significantly improved in the case of external H₂O₂,mineralization rate was high within 20 min and afterwards low.The order of three metal doped heteropolyacid catalytic activity is FePWV>AlPWV≈CuPWV.Finally,by dipping-grinding method,FePWV has been supported on the surface of Pd/C（Pd content of 5%）and immobilization heteropoly compound catalyst（Pd/C/FePWV）was obrained.The catalyst Pd/C/FePWV was applied into photoelectric Fenton process for degradation of phenol and the influences of factors,such as,different FePWV loading,catalyst dosage,pH,initial concentration of phenol,ultraviolet light,current,were discussed.The optimum conditions were that the dosage of Pd/C/FePWV（loading 20%）was 0.075 g/L,initial concentration of phenol 50 mg/L,pH=3,and current was 20 mA.The results show that the degradation rate of phenol and the removal efficiency of TOC is 84% and 69% under ultraviolet light,repectively.Experimental studies show that the structure of heteropoly compound can changes and weakens the catalytic effect under strongly acidic conditions（pH<1）.Moreover,H₂O₂ can be formed on the surface of Pd in situ.Photoelectric Fenton process has greatly solved the problems that purchase,transportation and storage of H₂O₂ and can improve the efficiency via preventing the recombination of electrons and holes in the case of the applied voltage.