Photo-Fenton Degradation Of Acetamprid And Sulfamethoxazole By Defects/Surface Modified Iron-Based MOFs

Since the biological activity of pesticides and antibiotics,they will cause great harm to human health and environment even at low concentration in aqueous water.And the stable structures make them hard to be degraded completely,the intermediates will also do harm to environment.In this thesis,acetamiprid and sulfamethoxazole,the typical representatives of pesticides and antibiotics,are selected for the photo-Fenton degradation studies.NH₂-MIL88B（Fe）（MIL88（Fe））with high specific surface area,high density and high dispersion of Fe metal sites is used as photo-Fenton degradation catalyst.Due to the low visible light utilization rate and high recombination rate of photo-generated electron-hole of MIL88（Fe）,modification of MIL88（Fe）through defects and surface modification.The main research contents and results obtained in this thesis are as follows:1.Based on the monodentate ligand strategy,three monodentate ligands benzoic acid（Bac）,pyrrole（Py）and pyrrole-2-carboxylic acid（Pca）with different coordination groups were selected to in-situ prepare different ligand defected MIL88（Fe）s.The prepared Bac-MIL88（Fe）,Py-MIL88（Fe）and Pca-MIL88（Fe）effectively improved MIL88（Fe）’s adsorption and photo-Fenton catalytic ability for ACTM at low concentration.The catalysts were characterized by FE-SEM,XRD,¹HNMR,XPS,NH₃-TPD,EPR,CO-DRIFTS,DRS,PL,EIS,CV,ESR,etc.The results demonstrated that the introduction of ligand defects improved MIL88（Fe）’s visible light absorption,photogenerated electron-hole separation,Fe²⁺|Fe³⁺redox ability and the amount of photo-Fenton generated·OH.The effects of different coordination environments of ligand defected MIL88（Fe）s on their photo-Fenton degradation performance of ACTM were investigated.The results indicated that Pca-MIL88（Fe）exhibited optimal catalytic activity,and its adsorption and catalytic rates were 7.3 and 5.5 times higher than that of the pristine MIL88（Fe）,respectively.Pca-MIL88（Fe）showed good recycling performance.In addition,the total organic carbon（TOC）conversion of ACTM by Pca-MIL88（Fe）was 97.0%within 90 minutes,which was 1.7 times higher than that of MIL88（Fe）.The intermediate products in the degradation process were analyzed using LC-MS,and a reasonable ACTM degradation pathway was proposed.The HOMO-LOMO energy level of the materials were simulated by density functional theory（DFT）,and Pca-MIL88（Fe）owned the lowest frontal orbit energy level difference of 2.03 e V,which was 0.51 e V less than that of MIL88（Fe）.2.Based on the strategy of polymerization within nanochannels of MOFs,polypyrrole（PPy）was used to modify Py doped MIL88（Fe）to prepare a novel MIL88（Fe）composite(PPy_a/p@Py_x-MIL88（Fe）),which improved the composites’photo-Fenton catalytic ability of sulfamethoxazole（SMZ）at low concentration.The catalysts were characterized by FE-SEM,XRD,ASAP,XPS,DRS,PL,EIS,CV,etc.The results showed that the introduction of PPy and Py in-situ improved the visible light absorption,photogenerated electron-hole separation,Fe²⁺|Fe³⁺redox ability of MIL88（Fe）.Additionally,the photo-Fenton degradation behavior of SMZ by PPy_a/p@Py_x-MIL88（Fe）composite photo-Fenton catalysts under visible light was studied.The effects of doping amount of pyrrole in Py_x-MIL88（Fe）,the adsorption time and polymerization time of pyrrole in PPy_a/p@Py_x-MIL88（Fe）on the catalytic activity of the photo-Fenton catalyst were investigated.The results showed that PPy_25/15@Py₉-MIL88（Fe）had optimal catalytic activity,and its catalytic rate was10.2 times higher than that of MIL88（Fe）.PPy_25/15@Py₉-MIL88（Fe）exhibited good recycling performance.