Preparation Of Graphite-Ptfe Cathode And Treatment Of Dye Wastewater By Electro-Fenton Reaction

In recent years, various treatment processes have been investigated to avoid the dangerous accumulation of the toxic dyes in the environment. Among of them, indirect electro-oxidation methods with electro-generated hydrogen peroxide, such as electro-Fenton (EF) and photoelectro-Fenton (PEF) processes, have been developed for the treatment of toxic and refractory organic pollutants in acidic water.The degradation of acid fuchsine, methyl orange and 2,4-dichlorophenol by electro-Fenton technique was studied in this paper. The current modified electro-Fenton system was designed to develop a more convenient and efficient undivided system for practical wastewater treatment. The system adopted a cathode portion, which employed magnetic stirring instead of common oxygen gas diffusion or gas sparging to supply oxygen gas for the electrolyte solution.The graphite-polytetrafluorethylene cathode was prepared and key factors influencing the cathode fabrication and activity were investigated. It was found that the cathode generated hydrogen peroxide with higher current efficiency when oxygen gas was supplied only by the magnetic stirring, and calcination temperature influenced the performance of the graphite-polytetrafluorethylene cathode remarkably. Hydrogen peroxide yield was the highest when the cathode with a ratio of graphite:polytetrafluorethylene of 4:1 (m/m) or of 3:1 (m/m) was calcinated at 350℃for 1 h. When the current density was 3 mA/cm2, pH was 3, the volume of electrolyte was 200 mL, and oxygen gas was supplied by the magnetic stirring, the concentration of H2O2 electrochemically generated by the graphite-polytetrafluorethylene cathode (12 cm2) was able to be 114 mg/L after 150 min. The hydrogen peroxide yield of the cathode did not decay after 10 times reuse. These results suggest the prepared cathode have a good stability and it can be used for practical wastewater treatment.At the same time, the degradation of acid fuchsine by the electro-Fenton systems with either a Fe anode or a Pt anode with external ferrous ion and a graphite-polytetrafluorethylene cathode were studied using a spectrophotometer. When Pt was used as anode and external ferrous ion was 0.5 mmol/L, the dye decolorization could be rapidly accomplished but the destruction of benzene rings and intermediates was difficult fairly. The dye degradation was more completive, when Fe was used as anode.The degradation of methyl orange and 2,4-dichlorophenol with various concentrations was also investigated by electro-Fenton system with a Fe anode and a graphite-polytetrafluorethylene cathode. The results showed that the electro-Fenton system was suitable for the lower concentration of 2,4-dichlorophenol and the dye decolorization for methyl orange was remarkable.