The Preparation And Photo-assisted Catalytic Degradation Properties Of The Magnetic Fenton-like Nanocatalysts

The main work of this thesis is to combine nanomaterials with excellent magnetic properties and nanomaterials with excellent Fenton-like catalytic activity for the catalytic degradation of organic pollutants.The combination can not only improve the efficiency of catalytic degradation,but also reduce the cost of recycling and application.In addition,by fully utilizing the abundant solar energy in the Fenton-like oxidation reaction system,the degradation efficiency of the reaction system can be further improved.Based on the research status of water treatment technology,the following three aspects of research have been carried out in this thesis.In the second chapter,magnetic CoFe₂O₄ nanoparticles were selected to be loaded on the surface of g-C₃N₄ nanosheets to prepare CoFe₂O₄/g-C₃N₄ Fenton-like catalysts with different mass fractions of CoFe₂O₄.The catalytic activity of the composite was evaluated by degrading the organic dye of Rhodamine B?RhB?in the presence of visible light and PMS?photo-assisted Fenton-like?.It was found that the photo-assisted Fenton-like catalytic activity of the composite was significantly higher than either CoFe₂O₄ or g-C₃N₄ alone.The CN-CoFe₂O₄-3 containing a CoFe₂O₄ mass fraction of 3%showed the optimal catalytic activity.The improved catalytic activity is closely related to the synergistic effect between Fenton-like oxidation and photocatalytic processes.Based on these results,a plausible reaction mechanism was proposed for the photo-assisted Fenton-like catalytic processes of CoFe₂O₄/g-C₃N₄accordingly.Finally,the catalyst has been proved to have broad applicability and good stability in the photo-assisted Fenton-like catalytic reactions,verified by changing the experimental conditions and cycling experiments.In the third chapter,CoNi alloy encapsulated in nitrogen-doped carbon nanotubes?CoNi@NCNT?was prepared and used as catalysts for catalytic degradation of RhB.The magnetic core-shell nanostructure can not only make the material easy to recycle,but also protect metal nanoparticles from corrosion and leaching.The Co²⁺,Ni²⁺-functionalized g-C₃N₄ was firstly carbonized in an N₂ atmosphere,and then CoNi@NCNT was obtained by washing using 0.5 mol/L sulfuric acid.The catalytic activitiy of the catalyst was evaluated by degrading RhB in the presence of simulated sunlight and PMS.A possible reaction mechanism was proposed for the photo-assisted Fenton-like process by aid of the trapping agent experiment.Finally,the catalyst has been proved to have wide applicability and good stability in the photo-assisted Fenton-like catalytic reactions,verified by changing the experimental conditions and cycling experiments.In the fourth chapter,CoNi alloy?CoNi@NG?coated with nitrogen-doped graphene nanospheres was prepared and used as catalysts for the catalytic degradation of RhB.CoNi@NG not only exhibits excellent PMS activation,but also shows good dye adsorption properties.In addition,after integrating CoNi@NG with g-C₃N₄ via?-?interactions,the composite of CoNi@NG/g-C₃N₄ exhibited superior catalytic activity compared with either g-C₃N₄ or CoNi@NG alone during the PMS-activated catalytic processes under visible light irradiation.Based on literature research and experimental results,a feasible reaction mechanism was proposed for the photo-assisted Fenton-like process.Finally,the catalyst has been proved to have broad applicability and good stability in the photo-assisted Fenton-like catalytic reactions,verified by changing the experimental conditions and cycling experiments.In this thesis,three novel Fenton-like magnetic nanocatalysts were synthesized and investigated for PMS-activated catalytic degradation of organic polluants,by adjusting the morphology and structure,with the goal of constructing efficient magnetic Fenton-like nanocatalysts.These catalysts have the characteristics of high activity and easy recovery,which are excellent application prospects.