Noble Metal Loaded Graphite Felt Electrode Preparation For Electrochemical Reduction Of Halogenated Organic Compounds

Due to the outbreak of the new crown epidemic,the use of chlorine-containing disinfectants has increased globally.As a result,the amount of Disinfection by-Products（DBPs）in the environment has increased.At the same time,other halogen-containing organics have also increased in the environment,and halogen-containing organics are harmful as for humans,animals and plants.The product of electrochemical reduction dehalogenation technology has attracted the attention of researchers because of its low toxicity and high efficiency.The efficiency of electrochemical reduction technology needs to be improved,and the reduction mechanism needs to be studied.Therefore,this research explores this problem by using the preparation of precious metal load electrodes and preliminary electrolysis.And the prepared electrode was characterized by SEM and XRD.The Ag-loaded graphite felt electrode was prepared by the electrodeposition method,the Ag loading was 1 mg/cm²,the preparation current was 50 m A,and the electrolyte concentration was 30 mmol/L Na NO₃.In the electrochemical reduction of Trichloroacetic Acid（TCA）,20 mmol/L Na₂SO₄ is used as the electrolyte,the current is 5 m A,the initial p H is 3.5,and the initial TCA concentration is 1 mmol/L,in an argon atmosphere The degradation rate of TCA can reach 99.58%after 150 minutes of reaction.The reaction of electrochemical reduction and degradation of TCA conforms to the degradation process follows the rule of quasi-first order reaction kinetics.In order to verify the type of reduction dehalogenation（direct or indirect reduction）,this study used preliminary electrolysis experiments and found that indirect reduction played a certain role in the electrochemical reduction of TCA on the Ag-loaded graphite felt electrode.Pd-loaded graphite felt electrodes were prepared by electrodeposition method to degrade monochlorophenol.Pd loading is 0.5 mg/cm²,preparation current is 5 m A,electrolyte concentration is 30 mmol/L Na Cl,and 30 mmol/L CH₃COONa is used to reduce 3-Chlorophenol（3-CP）for dechlorination.Electrolyte,the current is 5 m A,the initial p H is 7.5,and the initial 3-CP concentration is 1 mmol/L.The degradation rate of 3-CP can reach 95.81%after reacting for 150 min under argon atmosphere.The electrochemical reduction and degradation reaction of 3-CP conforms to the degradation process follows the rule of quasi-first order reaction kinetics.In order to verify the type of reductive dehalogenation（direct or indirect reduction）,this study used preliminary electrolysis experiments to find that the Pd-loaded graphite felt electrode played a role in the indirect reduction of the reduction and dechlorination of monochlorophenol,and it was incompatible with the Ag-loaded graphite felt electrode.Reductive dechlorination accounts for more than indirect reduction.After exploring the degradation of chlorinated organics by two kinds of electrodes,the best conditions for using two kinds of electrodes are 2-Bromophenol（2-BP）and 3-Bromophenol（3-BP）,4-Bromophenol（4-BP）has been degraded.It follows that the degradation of monobromophenol by the Ag-loaded graphite felt electrode showed that the degradation of monobromophenol by the electrode was better,reaching more than 80%,and the degradation rate of 3-BP reached 98.34%.The results of the degradation of monobromophenol by the Pd-loaded graphite felt electrode showed that the degradation of monobromophenol by the electrode is very good,reaching more than 98%,and the electrode has basically completed the degradation of monobromophenol in about 120 minutes.The electrochemical reduction and degradation reaction of monobromophenol conforms to the quasi-first order reaction kinetics.The electrochemical reduction and degradation reaction of monobromophenol conforms to the degradation process follows the rule of quasi-first order reaction kinetics.In order to verify the type of reductive dehalogenation（direct or indirect reduction）,this study used the experiment of preliminary electrolysis to find that the two kinds of electrodes played a certain role in the reduction and debromination time of monobromophenols.