Research On Performance And Flow Simulation Of Biochar Electro-fenton System For Sulfamethazine Treatment

The production and use of antibiotics of China rank first all over the world.Antibiotic residues can be detected in water systems nationwide in China.Antibiotics will do harm to health of human and animals after entering the environment,and induce the appearance of drug-resistant bacteria and drug-resistant genes.How to reduce the total input of antibiotics to the environment has become the focus of environmental research.Sulfamethazine（SMR）is an antibiotic that has been used in aquaculture and animal husbandry for a long time.Long-term use of SMR has resulted in a large number of wastewater which is difficult to degrade with biological methods.Advanced oxidation process has become the worldwide research focus of environmental scholars cause its rapid and efficient degradation of refractory pollutants.Among them,the Electro-Fenton technology has been widely concerned because it overcomes the weakness of Fenton technology,such as large iron-sludge volume,H₂O₂ transportation danger,and uncontrollable degradation process.The research focus of the Electro-Fenton technology is on the preparation of cathode materials.Due to the developed pore structure,high specific surface area,rich functional groups,inexpensive and easily available characteristics,biochar materials have become the ideal option of cathode material.In this paper,the pinecone biomass material obtained from the school campus and the pinecone biochar material is obtained by one-step pyrolysis after pretreatment.The pinecone biochar modified iron-foam electrode（PBS）was prepared by roller-pressing the pinecone biochar to the Iron-Foam.SEM results show that the surface of the pinecone biochar has a complex layered pore structure.BET and BJH results show that the pinecone biochar prepared at 700℃ has a specific surface area of 532.70 m²/g,and the biochar material contains a lot of microporous and mesoporous structure.FTIR and XPS results show that the types and amount of aromatic functional groups of biochar materials are increasing with the pyrolysis temperature going high,and the pinecone biochar containing pyridine nitrogen,pyrrole nitrogen and oxygen-containing functional groups is conducive to improving the production of the H₂O₂ and the hydrophilicity of cathode.RDE results show that the ORR reaction type of the pinecone biochar cathode prepared at 600℃-800℃ is a two-electron ORR reaction,and the number of transferred electrons is around 2,which has proved that the prepared cathode has a good two-electron ORR selectivity.The prepared PBS electrode was applied to the Electro-Fenton system to explore its degradation performance of SMR,and the experimental analysis was carried out using UPLC detection methods.The best operating conditions were obtained that when the pyrolysis temperature of the pinecone biochar is 700℃,the current density is selected as 25 m A/cm² and the p H is selected as 3,the SMR removal rate can reach 71.82% in 180 min,which proves that the prepared PBS cathode has a good Electro-Fenton performance.The Fluent software was used to model the Electro-Fenton reactor,and appropriate Viscous,Multiphase and Species Transport models were selected according to the movement characteristics of the reactor fluid.The effects of reactor air-input and cathode plate morphology on reactor fluid behavior were investigated.The simulation results show that high air volume fraction,high oxygen mass fraction and high fluid velocity near the cathode plate can be maintained at a high air-input speed of 800 m L/min,making the oxygen mass transfer efficiency much more better.The porous surface cathode can effectively improve the mass transfer of oxygen in the horizontal direction and into the inside of the cathode plate.Porous morphology can effectively improve the turbulence intensity near the cathode of the reactor and enhance the effect of oxygen mass transfer.The pinecone biochar cathode Electro-Fenton system successfully constructed in this study has a good effect on the degradation of SMR.Using the Fluent model to make a reasonable prediction of the fluid behavior and the oxygen mass transfer in the Electro-Fenton reactor makes this study having good theoretical value and application value.