Carbon Felt Modified By Electrodeposited Anthraquinone And Conductive Polymer As A New Cathode And Its Application In Electro-Fenton

Electro-Fenton,as a representative technology,has attracted many attentions because it can continuously produce hydroxyl radicals（·OH）by using an electrochemical method to enhance the radical production in the reaction system to strengthen the degradation efficiency.The adequate amount of the electro-generated H₂O₂ can ensure the degradation efficiency of the Fenton process,which was determined by the electrochemical activity of the cathode.In order to improve the electrocatalytic activity of cathode materials,carbon felt cathodes modified with polypyrrole doped with anthraquinone molecules and polyaniline doped with anthraquinone molecules conductive polymer films were prepared,respectively.The performance,influencing factor and mechanism of the electro-Fenton process with the newly prepared cathode were further investigated.The carbon felt electrodes of anthraquinone sulfonate（AQS）doped polypyrrole（PPy）films were fabricated by constant voltage method and cyclic voltammetry in the first part of this experiment.The electrochemical performance test and characterization results show that the electrochemical performance of carbon felt electrode modified by polymer and anthraquinone was obviously improved,and the electrode prepared by cyclic voltammetry（10-CV）is better than that prepared by galvanostatic method（TPED）.Then the electrode before and after modification was further used as cathode material in the electro-Fenton system.The degradation efficiency of Rhodamine B（Rh B）reached to99.77%within 1h in electro-Fenton with 10-CV cathode under the optimal conditions.However,the degradation efficiency of Rhodamine B（Rh B）reached to 93.85%within1h in electro-Fenton with TPED cathode under the optimal conditions,showing the electrocatalytic performance was slightly inferior to that of the 10-CV electrode.According to the results of repeated experiments,the average degradation rate of the six repeated experiments of 10-CV electrode was 99.49%,which was not significantly different from the initial experiment.However,the degradation rate of the TPED electrode was obviously changed after six repeated experiments.And the degradation rate of the last experiment was only 84.81%,which was significantly lower than that of the first time.The carbon felt（CF）modified with 2-anthraquinone sodium sulfonate and polyaniline（AQS/PANI/CF）by electrochemical deposition method was used as an cathode in electro-Fenton system.The experimental results showed that the electron transfer resistance of AQS/PANI/CF cathode decreased dramatically by 99.87%compared with that of the bare carbon felt.The LSV and CV tests showed that the current response of AQS/PANI/CF cathode elevated significantly.It indicated the electrochemical activity of CF was improved after modification.When the cathode was poised at-0.5V vs Ag/Ag Cl,the yield of the electro-generation H₂O₂ on AQS/PANI/CF cathode was nearly 10 times higher than that of the bare CF cathode.The degradation efficiency of Rhodamine B（Rh B）reached to 96.46%within 1h in electro-Fenton with AQS/PANI/CF cathode under the optimal conditions.The free radical quenching experiment and the EPR test were also carried out to explore the mechanism of the degradation process in electro-Fenton system with AQS/PPy/CF and AQS/PANI/CF as cathode,respectlly.Anthraquinones received electrons from a cathode to form semiquinone(SQ^·-)by one-electron reduction steps,and subsequently,the SQ^·-as an electron donor could be responsible for the formation of O₂^·-with the one-electron reduction of O_2.Thus,the amount of the produced O₂^·-accumulated and subsequently resulted in the enhancement of the H₂O₂generation under the catalysis of anthraquinone.Thus,the quinone（AQS）catalyzed ORR to generate H₂O₂ through a two-electron reduction process.The catalytically generated H₂O₂reacted with additional ferrous ions to form hydroxyl radical which could efficiently decompose organic matter.