Development Of Threedimensional Electrocatalytic System For Organics Degradation:Novel Particle Electrode Preparation,Performance Evalution And Mechanism

Water is the substance on which all life depends.But with the rapid development of industry,not only the total annual discharge of various organic wastewater is growing rapidly,but also the wastewater containing refractory organic pollutants is increasing.The objective of this study is the efficient removal of refractory organic pollutants.Focusing on three-dimensional electrocatalytic oxidation technology,to developed a set of three-dimensional system with wide adaptability as the research goal,and the preparation of efficient and stable filled particle electrodes as the main content.Optimize the three-dimensional reactor and the revelation of the electrocatalytic oxidation mechanism.The results show that the three-dimensional system had excellent effect on the treatment of refractory wastewater and achieved continuous and stable operation.The traditional three-dimensional electrocatalytic oxidation system considers that the efficient removal of pollutants relies on the anodic oxidation of H₂O into·OH at the anode side of the bipolar particle electrodes.Therefore,Ti₄O₇ with high oxygen evolution potential,good electrical conductivity and strong mechanical properties was selected as the particle electrode.The effects of current density,electrolyte concentration,electrode spacing,and the amount of added glass spheres on the degradation of phenol in a three-dimensional system filled with Ti₄O₇ particles were investigated.Under the optimal experimental conditions,the removal efficiencies of phenol and COD were 84%and 48%,respectively,after 120 min of reaction,and the energy consumption was 0.762 kWh g^-1 COD.In addition,carbon black particles with excellent H₂O₂ production performance were selected as fillers to investigate the mechanism of pollutant degradation at the cathodic side of the bipolar particle electrodes.The three-dimensional electro-Fenton system filled with carbon black particles at optimal 0.2 mM Fe²⁺addition and 10 mA cm^-2 current density showed 99%phenol removal after 75 min of reaction,76%COD degradation efficiency after 120min,and the energy consumption is 0.082 kWh g^-1 COD.The results showed that the three-dimensional system with filled particles has obvious advantages for phenol removal.However,relying on the anode side of the bipolar particle electrodes to mineralize pollutants requires huge energy consumption and the degradation effect was not satisfactory.The three-dimensional electro-Fenton system relying on the cathodic side of the bipolar particle electrodes requires low energy consumption and has high degradation efficiency.Taking advantage of the three-dimensional electro-Fenton system,in this paper,iron-copper-carbon black（Fe-Cu-C）particles with dual functions were fabricated through a one-step process of pyrolyzing the metal-resin precursors and worked as the particle electrode in the three-dimensional electrocatalytic reactor to degrade p-nitrophenol（p-NP）.Material characterization by SEM,BET,XRD and XPS,and electrochemical analysis by LSV,CV and EIS showed that the Fe-Cu-C particle has abundant pore structure and high electrocatalytic activity.The Fe-Cu-C particles were polarized under the electric field,and the anode-to-cathode flow three-dimensional electrocatalytic reactor created a locally acidic zone,which facilitated the H₂O₂generation from 2-electron reduction of O₂ and decomposition into·OH via heterogeneous Fenton reaction.Consequently,it was found that average p-NP removal efficiency of 88%and average COD removal efficiency over 76%were achieved during6 h continuous operation in the three-dimensional electro-Fenton system,and the degradation effect was stable.Noticeably,the anode-to-cathode flow three-dimensional electro-Fenton system had the appreciable anti-scaling ability to resist the deactivation of particle electrodes induced by hardness ions,and had excellent treatment effect in the range of solution pH=4.0～10.0 with specific energy consumption of approximately 0.089 kWh g^-1 COD.Generally,this system realized continuous generation of·OH for effective complex wastewater purification by coupling the pH self-regulated three-dimensional electrocatalytic reactor and bifunctional Fe-Cu-C particle electrodes.