Study On The Preparation Of Iron-based Fenton-Like Catalysts And The Degradation Of Organic Pollutants In Water

The rapid development of industry has brought about a series of environmental problems as well as the economic growth.Organic pollution is one of the most prominent environmental problems.Most organic pollutants are highly toxic and harmful,and can seriously endanger the survival of humans and animals even the stability of the ecosystem.Because of their stable chemical structure and complex occurrence in water,traditional treatments such as adsorption,flocculation,precipitation,biochemical technology cannot completely removed it,and finding a more effective treatment has become an important research topic for solving such problems.The Fenton technology in advanced oxidation technology can quickly degrade organic pollutants and convert them into non-toxic small molecules,which is of great concern in environmental treatment.However,due to its high cost,large amount of iron sludge,and strict p H range,the traditional homogeneous Fenton technology cannot be widely used in actual industrial processing.The heterogeneous Fenton technology improved on the basis of the homogeneous Fenton technology has excellent application prospects in the field of wastewater treatment;and the iron-based materials in the transition metals have the advantages of non-toxic,high efficiency,and wide sources;Inorganic materials such as graphene,MOFs,BN,etc.not only have a large specific surface area,but are also good metal supports,which can form coordination bonds with metals to fix metals and their oxides on inorganic materials,forming highly efficient heterogeneous catalysts,which could well remove organic pollutants in the water.Based on the advantages of the above materials,this thesis prepared an iron-based Fenton catalyst based on inorganic materials（MOFs,BN）to activate hydrogen peroxide to degrade organic pollutants（sulfadiazine,methylene blue）in water,and study its Degradation performance and mechanism.The specific content is as follows:（1）single-atom iron fixed on nitrogen-doped porous carbon materials（Fe-ISAs@CN）was synthesised using a metal organic framework（MOF）as a precursor.Fe-ISAs@CN was applied as a Fenton-like catalyst to activate H₂O₂ for the degradation of sulfadiazine（SDZ）in an aqueous solution.A large number of characterization methods were used to determine the microscopic morphology,structure and catalytic activity of the material.The results of our degradation experiments indicated that Fe-ISAs@CN exhibited remarkable activity and stability for the degradation of SDZ over a wide p H range;even after five cycles,Fe-ISAs@CN retained a high catalytic efficiency（>80%）.The 5,5-dimethyl-1-oxaporphyrin-n-oxide（DMPO）-X signal captured by electron paramagnetic resonance（EPR）spectroscopy indicated that a large amount of hydroxyl radicals（·OH）was produced in the reaction system.Quench tests indicated that the·OH was the main active substance in the degradation of SDZ.The degradation products of the reaction were analysed by High Performance Liquid Chromatography-Mass Spectrometry（HPLC-MS）,and possible degradation pathways for the SDZ degradation were proposed.（2）The two-dimensional flake material Fe-BN was synthesized by hydrothermal method together with high temperature calcination method,its microscopic morphology and structural characteristics were determined through the characterization of the material,and it was used to activate H₂O₂ to oxidize and degrade methylene blue（MB）in water.The porous structure of the material can absorb a large amount of MB,after the adding of H₂O₂,a large amount of MB was degraded.Under the best reaction conditions,almost all MB has been completely removed after 120 minutes;In addition,we explored the influence of Fe-BN dosage,H₂O₂ concentration,initial p H and other factors on the degradation effect;the recycling performance and stability was determine by the cycle experiment;according to the quenching experiment,both·OH and O₂·^-have participated in the degradation reaction,and·OH played the major role.