Degradation Of Phenol Containing Wastewater With Ti/RuO₂-IrO₂-SnO₂ Electrode In Multistage Concentric Cylinder-rotating Bed

Electrocatalytic oxidation technology has attracted the attention of many scholars due to its advantages of not need to add any chemical reagents and no secondary pollution during the reaction process.However,the research of this technology is mostly in the experimental stage and has not actually been put into industrial application,because of the level of its industrial application is low and the performance of the electrode materials is unstable.Based on this understanding,electrode materials which own good stability and high catalytic activity have become the hotspots for improving the wastewater treatment effects of this technology.At the same time,the bubbles attached to the surface of electrode during the electrocatalytic oxidation reaction will cause the cell voltage rise.The unreasonable shape and layout of the electrode will cause the problem of material transfer limitations among the electrodes.Based on this,eliminating or reducing the influence of bubbles on the reaction process and enhancing the liquid-phase material transfer rate among the electrodes have become the goals which are pursued.Therefore,the selection of electrode materials,the design of the electrode shape and the layout of the structure have become the key to the problem.For this reason,the Ti/RuO₂-IrO₂-SnO₂ electrode with high catalytic activity,good stability and high oxygen evolution potential was selected as the anode,stainless steel as the cathode,and the high-gravity created by the Multistage Concentric Cylinder-Rotating Bed?MCC-RB?electrocatalytic reaction device was used as the reaction environment.In order to provide the theoretical basis for the industrial application of electrocatalytic oxidation technology,the experiment of electrocatalytic oxidation phenol was studied.Firstly,the electrochemical properties of the selected anode materials were investigated with online detection system.The influence of various factors on the phenol oxidation peak current was investigated through a three-electrode system,and the process parameters were optimized.The analysis showed that the reaction occurred on the Ti/RuO₂-IrO₂-SnO₂ anode was mainly controlled by the diffusion step under suitable operating conditions,and the polarization current was increased by 16%,the polarization potential was reduced by 9.6%and the electrical resistance was reduced by 84.9%than that in the conventional gravity field,which means that the anode in the MCC-RB device can increase the polarization current,reduce the polarization voltage and overpotential,and reduce the polarization resistance of the reaction to a certain extent,and it also achieve the purpose of reducing energy consumption and accelerating the reaction mass transfer efficiency.Secondly,high performance liquid chromatography?HPLC?was used to analyze the degradation route of phenol with Ti/RuO₂-Ir O₂-SnO₂ anode in the MCC-RB device.First,the hydroxyl radical attacked the benzene ring to form hydroquinone and p-benzoquinone,and then the conjugated system was broken and opened.It produces cis and fumaric acid,and further produces succinic acid and other substances through oxidation-reduction reaction,and finally mineralizes to CO₂ and H₂O.Finally,the single-factor experiment was used to optimize the process parameters,and the appropriate operating conditions were determined.The results showed that in order to degrade 6 L simulated phenol solution with an initial concentration of 500 mg/L,35 mA/cm²current density,48 L/h liquid circulation flow rate,20 high gravity factor,and 8.5 g/L sodium chloride concentration,6.5 pH value were required.The removal rate of phenol was reached99.7%after 100 min,which was about 10.4%higher than that in the conventional gravity field.In addition,the removal rates of TOC and COD in the high gravity field and conventional gravity field were compared.The results showed that the TOC removal rate in the high gravity field was increased by 8.4%compared with the conventional gravity field,and the COD removal rate was increased by 14%.The high gravity field enhancing the reaction mass transfer process was further proved.Based on the above studies,the kinetics of the reaction in the high gravity field was linearly fitted.The study showed that the reaction process conforms to the first-order reaction kinetics model in the high gravity field,and it also found that the high gravity field could accelerate the reaction degradation rate,but it won't change the reaction route.