Preparation Of Fe₃O₄-PTFE Electrode And CoFe₂O₄-PTFE Electrode And Study On Electro-Fenton Degradation Of Dye Wastewater

Fenton reaction which can generate hydroxyl radicals with strong oxidizing properties has been widely used in the treatment of organic pollutants in wastewater,but the traditional Fenton reaction still has some limitations in practical application.In recent years,electro-Fenton oxidation technology has made remarkable progress in the degradation of refractory organic compounds.One of them is forming hydroxyl radical directly by Fenton reagent in the electrolysis cell and the forming of ferrous ion by reduction reaction of iron ion at the cathode.This eliminates the need for acidic conditions in the reaction solution.In this paper,the Fe₃O₄-PTFE electrode was prepared by using Fe₃O₄ powder that is the active component at first.And the feasibility and optimum preparation conditions of Fe₃O₄-PTFE electrode were investigated.The experimental results show that the Fe₃O₄-PTFE electrode is feasible to participate in the electro-Fenton reaction.When the mass ratio of Fe₃O₄ to PTFE is 3:2.5 and the calcination temperature is 300℃for 1 h,the performance of Fe₃O₄-PTFE electrode is the best.In a single cathode electrochemical system with Fe₃O₄-PTFE electrode as cathode and platinum electrode as anode,the decolorization rate of dye solution reached 86.91%.This is owing to the change of configuration and magnetic transformation of Fe₃O₄.Then,CoFe₂O₄-PTFE electrode was prepared by self-made CoFe₂O₄ powder sample.And investigate whether solid CoFe₂O₄ is similar to solid Fe₃O₄,that is to say its divalent cobalt also can participate in Fenton reaction,because Co²⁺is more likely than Fe²⁺to trigger Fenton class reactions.The experiment results show that CoFe₂O₄-PTFE electrode is also feasible to participate in electro-Fenton reaction.When the mass ratio of CoFe₂O₄and PTFE is 3:2,and the calcination temperature is 250℃for 1 h,the performance of CoFe₂O₄-PTFE electrode is the best.In a single cathode electrochemical system with CoFe₂O₄-PTFE electrode as cathode and platinum electrode as anode,the decolorization rate of dye solution reached 95.05%.Finally,the Fe₃O₄-PTFE electrode and the CoFe₂O₄-PTFE electrode are connected in parallel with the acetylene black-PTFE composite gas diffusion electrode respectively to form a double cathode,which is forming a double cathode electrochemical system with Pt anode.And the acetylene black-PTFE composite gas diffusion electrode can product H₂O₂by electrolytic in the electrolysis cell.The experimental results show that it is feasible to treat the dye wastewater by using the electric-Fenton system with parallel double cathodes,and the performance of the parallel double cathode system is better than that of the single cathode system.Under the operating conditions of the voltage is 6 V and pH value is 3,the dye decolorization rate of the Fe₃O₄-PTFE parallel double cathode system reached 91.65%,and the decolorization rate of the CoFe₂O₄-PTFE parallel double cathode system reached94.07%.It indicates that CoFe₂O₄ is more active than Fe₃O₄ in this work.