Effect And Mechanism Of Graphite Felt Electro-Fenton System On The Degradation Of Dyes In Water

As a kind of environmentally friendly advanced oxidation process for water treatment,electro-Fenton?E-Fenton?technology has received widespread attention in recent years.However,choosing a kind of electrode material with low price and good performance has always been a problem for practical application of E-Fenton technology.Graphite felt as a kind of carbon–based three-dimensional electrode is often used as the cathode of the E-Fenton system.However,there are few reports using graphite felt as the cathode and anode of the E-Fenton system.There is also less attention to the generation and evolution of Fenton reagents?H₂O₂ and iron ions?in the system,the durability of electrode materials,and the changes in performance of electrode materials before and after use.Choosing graphite felt as the electrode of the E-Fenton system,which has a certain adsorption property for organic matter,can overcome the disadvantages of poor corrosion resistance and dissolution of metal anode,solve the problem of high price of noble metal electrode,and also make full use of the efficient performance of H₂O₂.Therefore,in this paper,methylene blue was used as an indicator pollutant,and the application performance of graphite felt in the E-Fenton system was systematically studied in order to provide a reference for the related research of graphite felt in the E-Fenton system.The research contents of this article mainly included the following three aspects:?1?Influence factor optimization experiment.In this paper,the influencing factors and optimal conditions for the degradation of methylene blue by graphite felt E-Fenton system were first determined.With 500 ml of methylene blue at a concentration of 20 mg/L and 10 mmol/L of Na₂SO₄as supporting electrolyte,the effects of various factors on the removal rate of methylene blue were investigated by adjusting the voltage,pH,catalyst type and Fe²⁺concentration,and the optimal conditions for methylene blue removal were obtained.Under the conditions of voltage 7 V,pH 3.0and 0.2 mmol/L Fe²⁺as catalyst,the removal rate of methylene blue can reach 97.80%after electrolysis for 20 min.?2?Degradation mechanism of methylene blue by graphite felt E-Fenton system.In order to further understand the degradation mechanism of pollutants by the E-Fenton system,the generation of H₂O₂ and the evolution law of iron ions in the graphite felt E-Fenton system were explored,and the optimal value of voltage 7 V and pH 3.0 was determined,which was consistent with the voltage and pH value determined by the optimization experiment.The inhibition experiments showed that the graphite felt Fenton system mainly oxidized methylene blue by direct anode oxidation and·OH oxidation.?3?Reuse experiments and performance changes.In order to explore the stability of graphite felt as electrode,the experiment of reusing graphite felt electrode was carried out.The results showed that the graphite felt electrode system showed good electrochemical stability,and the methylene blue removal rate only decreased by 26.02%after 90 times of repeated use.As a cathode,the graphite felt had stable performance,while as an anode,the catalytic and conductive properties declined,and the adsorption performance was greatly improved.The anodes were characterized by SEM,XPS,contact angle,XRD,and BET tests.The results showed that changes in surface structure,hydrophilicity,and functional groups affected the resistance,adsorption,and catalytic properties of graphite felt.The large increase of oxygen-containing functional groups did not make the anode function as a cathode.Therefore,it is believed that the catalytic performance of oxygen-containing functional groups on the surface of carbon materials does not originate from a single functional group,but from the synergy between other types of adjacent functional groups.