Three-dimensional Heterogeneous Electro-fenton Particle Electrode Preparation Degradation Of Performance Evaluation And The Reaction Mechanism Research

With the acceleration of industrialization,the problem of water environmental pollution has become increasingly prominent.The discharge of refractory organic wastewater is increasing and direct discharge will cause serious harm to the environment.Based on the strengthening effect of particle electrode,three-dimensional electrochemical reaction system can realize the efficient removal of pollutants,which has attracted wide attention in the field of organic pollutants treatment in water.In traditional homogeneous Fenton system,^·OH generation often require continuous dosing of H₂O₂,H₂O₂ transportation extremely inconvenient,however,this leads to homogeneous Fenton system in actual industrial application.The traditional three-dimensional electro-Fenton system has some defects,such as high operating cost,poor catalytic effect and high pH influence.In view of the above bottleneck problems,this study proposed to prepare low-cost and efficient three-dimensional electro-Fenton particle filler,develop a three-dimensional electrochemical reactor with acid base self-regulation,evaluate its oxidation and degradation performance of typical organic pollutants in water,and describe the reaction principle of three-dimensional electro-Fenton reaction process.In this study,carbon black particles（C-PTFE）with 2-electron O₂ reduction activity and Fe-Co-C Fenton catalysts with H₂O₂ catalytic performance were prepared respectively.The flowing three-dimensional reaction system with anode-cathode was developed,and the H⁺produced by the anode electrolysis was used to create an acidic atmosphere in the filler region,so that the pH value of the electro-Fenton core reaction zone was maintained at about 3,which was not only conducive to the generation of H₂O₂,but also strengthened the generation of^·OH.In the packing area,the ratio of C-PTFE to Fe-Co-C was 5:4.The experimental results show that when the current density is 10 m A cm^-2,the initial pH value is 3,the aeration rate is 300m L min^-1,the dosage of C-PTFE and Fe-Co-C particles is 10 g and 8 g respectively,the degradation efficiency of carbamazepine is 100%and the COD removal rate is 80.6%after 60min reaction.The energy consumption is much lower than the similar three-dimensional electrocatalytic reaction system,only 0.0077k Wh g^-1 COD.When current density increased from 5 m A cm^-2 to 10 m A cm^-2,carbamazepine removal rate increased from 81.7%to 100%,COD removal rate increased from 55.6%to 80.6%,and when current density further increased to 15 m A cm^-2,carbamazepine and COD removal rates were reduced to 92.5%and 71%respectively.When the influent pH value increased from 3 to 9,the removal rate of carbamazepine decreased from 100%to 92%,and the removal rate of COD decreased from80.6%to 67%.In addition,we further studied the effect of Cl^-on pollutant degradation in the three-dimensional electrocatalytic system.As the concentration of Cl^-in the system increased from 0 m M to 20 m M,the removal rate of carbamazepine decreased from 100%to 88.6%,and the removal rate of COD decreased from 80.6%to 68%.In addition,CB/GAC particle electrodes with higher mechanical strength and Fe-Co/GAC particles with lower production cost were prepared on the basis of C-PTFE and Fe-Co-C particles.It is worth noting that the improved anodic-cathode flow reactor,because of the separation effect of PTFE membrane,allows H⁺produced by the anode plate to accumulate continuously and participate in the system cycle,while the OH^-produced by the cathode plate is confined to the cathode room,ensuring that the overall pH value of the solution is maintained at a low level conducive to the electro-Fenton reaction.The electrocatalytic performance of CB/GAC particles was optimized.When the dosage of PTFE was 12 g and phenolic resin was6 g,the concentration of H₂O₂produced by electrocatalysis in situ was the highest(182.5 mg L^-1).When the current density increases from 10 m A cm^-2 to 20 m A cm^-2,the removal rate of phenol and COD increases from 78.4%to 81%and 50.4%to 72.5%respectively.When the current density is further increased to 30 m A cm^-2,the removal rates of phenol and COD decrease to 71.5%and 63.9%,respectively.This indicates that the higher the current density,the more intense the side reactions will be and the lower the pollutant removal efficiency.In addition,the influence of pH value on the three-dimensional system is further discussed.When the influent pH paper is increased from 3 to 9,the removal rate of phenol and COD decreases from 82.4%to 79.7%and 73.2%to 71.6%,respectively,by 2.7%and 1.6%.The experimental results show that the pH self-regulating device has a wide range of pH adaptation.The yield of H₂O₂ plays a crucial role in the degradation efficiency of three-dimensional system.In view of this,the effects of different aeration rates on the degradation of phenol were investigated.When aeration rates increased from 100 m L min^-1 to 300 m L min^-1,the removal rate of phenol increased from 69.7%to 80.9%.COD removal rate increased from 62.2%to 72.5%.When the aeration rate is further increased to 400 m L min^-1,the removal rates of phenol and COD only increase by 1.7%and 2.8%.In addition,when the influent flow rate increases from 10 m L min^-1 to 20 m L min^-1,the phenol removal rate increases from 59.2%to 80.9%,and the COD removal rate increases from 66.4%to 72.5%,and when the flow rate further increases to 30 m L min^-1,The removal rates of phenol and COD only increased by 2.7%and 3.3%.In general,two particle catalysts with different functions were prepared in this study,one of which could realize efficient in-situ synthesis of H₂O₂,and the other could realize efficient activation of H₂O₂ at low cost,thus avoiding potential dangers of H₂O₂ in the transportation process.In addition,the synthesis and activation of H₂O₂ were enhanced by coupling the synthesized particle electrode with the pH self-regulating reactor,which provided a new idea for the industrial application of the particle electrode.