Study On Structure And Composition Regulation And Pollutant Degradation Performance Of Iron-based Heterogeneous Electro-Fenton Materials

Traditional Fenton degradation technology needs to continuously add ferrous ions to the reaction system.A large amount of iron sludge is produced in the degradation process,which is difficult to recycle,and the reaction activity will be greatly reduced.On the other hand,hydrogen peroxide needs to be continuously added to the reaction system.Heterogeneous electrofenton technology can effectively solve the sedimentation of iron sludge and may realize the in-situ generation of H₂O₂,which has become one of the effective ways to degrade organic pollutants in water.However,at present,the heterogeneous electrofenton technology still has the problems of single function,low catalyst activity,narrow applicable p H range,poor stability,low H2O2generation efficiency and high energy consumption.The activity and stability of the catalyst can be adjusted by changing the morphology and structure or compounding with other metals,which is expected to improve the pollutant degradation performance of iron-based heterogeneous electro Fenton catalyst and enhance the tolerance and reuse stability of the catalyst in different p H environments.Based on the above considerations,this paper starts with regulating the pore structure,metal composite ratio,carburized layer thickness and thermal decomposition temperature of the catalyst,and improves the degradation performance of iron-based electrocatalytic materials by introducing MOFs framework,core-shell structure,cementite and light synergy.The specific research contents are as follows:(1)MIL-53(Fe)/carbon felt catalyst was prepared by solvothermal method with terephthalic acid as organic ligand and ferric iron as central metal.MOFs materials with large specific surface area and rich pore structure can effectively adsorb pollutants in water.Changing the ratio of organic ligand to central metal can regulate the specific surface area of MOFs materials.Large specific surface area can improve the degradation rate of pollutants.The test results show that the synthesized MIL-53(Fe)/carbon felt-1 catalyst can achieve 27.7%static saturated adsorption capacity,and the degradation rate of the catalyst reaches 99.9%in 80 minutes under acidic conditions.After five cycles of test,the degradation performance of the fifth time still remains 90%of the initial degradation performance.(2)Using glucose as carbon source,a hollow tubular carbon coated copper coupled iron/ferric carbide catalyst was synthesized through two-step process of hydrothermal and pyrolysis.The proportion of metal in the catalyst and the thickness of carburized layer can be adjusted by adjusting the iron/copper feed ratio and carbothermal reduction temperature.The experimental results show that the catalyst shows good durability and catalytic activity in acidic,neutral and alkaline environments,and achieves 99%degradation rate and 85.3%mineralization rate in 30 minutes.The average electron transfer number of the catalyst is determined to be 2.5 by rotating ring disk electrode test,which has high two electron oxygen reduction selectivity,and its hydrogen peroxide yield is as high as 87%.At the end of this chapter,carbon coated copper coupled iron/carbide ferric carbide catalytic electrodes were used as cathode and boron doped diamond(BDD)as anode to form two electrode system.The degradation of a waste water from a cellar bottom of a Baijiu(BOD=50000 mg L^-1,BOD₅/COD=0.129)was conducted.In the reaction process,the cathode produces a large number of hydroxyl radicals,which can effectively reduce the energy consumption of the system and significantly improve the pollutant removal efficiency.Compared with the traditional process,it has great advantages in shortening the treatment time and reducing the cost.Compared with the traditional electrode group using BDD as anode alone,it can save energy by 14.3%.(3)A cuprous oxide-iron foam composite heterogeneous electro-Fenton electrode was designed and synthesized by three steps of replacement,oxidation and thermal decomposition for photoelectric synergistic degradation of pollutants.Different morphology modifiers can be used to obtain catalysts with different surface morphologies.The experimental results show that cuprous oxide has a special electronic structure,which can generate free radicals under the condition of light,and synergize with the Fenton-like reaction of copper to accelerate the degradation efficiency of pollutants and reduce power consumption.When HMT was used as a morphology modifier,the obtained cuprous oxide-iron foam composite electrode with a sheet-like hierarchical network structure had excellent photoelectric Fenton reaction activity.Compared with the dark condition,the degradation ability is increased by230%.This light-assisted electrocatalytic degradation technology effectively reduces the consumption of electricity,thereby reducing the cost of pollution treatment.