Study On Construction Of MOFs@PIL Activated Perosulfate Electrocatalyst And Synergistic Degrading Antibiotics

Peroxynitrite（PS）advanced oxidation processes is one of the practical means to solve the environmental pollution problem by activating the peroxide bond in PS to generate oxidation-capable sulfate radicals.The use of transition group metal ions Fe²⁺for PS activation has the advantage of being inexpensive and non-toxic,but it also has some disadvantages.For example,the active Fe²⁺cannot be regenerated after conversion to Fe³⁺,while activation of PS requires a high concentration of Fe²⁺,which will lead to the generation of a large amount of iron sludge in the PS catalytic decomposition reaction system,which both increases the cost and affects the reaction efficiency.The problem can be improved by adopting a combination of electrochemical and transition group metal ion activation.The metalized porphyrin-based metal-organic frameworks（PMOFs）are capable of good electrical activation of PS.To further improve the performance of PMOFs-activated PS,various composite catalytic materials were constructed using different poly（ionic liquid）s（PIL）to coat PMOFs.And through testing and analysis,the reasons for the improved performance of composite activated PS were derived.The article is divided into three main parts as follows:（1）Preparation,properties and catalytic mechanism of PMOFs（PCN-224（Fe））.PCN-224（Fe）was prepared by hydrothermal synthesis of PMOFs with ortho-hexahedral structure on FTO conductive glass and metallization of them.The activation PS efficiencies of PCN-224 and PCN-224（Fe）were analyzed by tetracycline（TC）degradation experiments,and the MOFs were analyzed by XRD（X-Ray Diffraction）,XPS（X-ray Photoelectron Spectroscopy）,SEM（Scanning Electron Microscope）,FT-IR（Fourier Transform infrared spectroscopy）,and electrochemistry to characterize the crystal structure,microscopic morphology,and electrical properties of the materials.The analysis shows that the metalized PCN-224activation PS system has better degradation effect on TC compared with the unmetallized PCN-224,and it shows good PS activation efficiency at lower Fe（Ⅱ）content.The analysis of the catalytic degradation mechanism shows that the Fe-porphyrin structure has a positive effect on the electro-activation of PS by PMOFs,and further tests show that the Fe-porphyrin structure can effectively contribute to the valence transition of Fe（Ⅱ/Ⅲ）during the reaction.（2）Preparation,properties and catalytic mechanism of MOFs@PIL(PCN-224（Fe）@PIL(S₂O₈^2-)).The PCN-224（Fe）@PIL(S₂O₈^2-)composites were prepared by UV polymerization with imidazolium-based PIL layer over PCN-224（Fe）material by counter-anions exchange method.The crystal structure,microscopic morphology and electrical properties were also characterized by XRD,XPS,SEM,FT-IR and electrochemical tests.The TC degradation experiments revealed that the PCN-224（Fe）@PIL(S₂O₈^2-)activated PS system has better degradation effect on TC and shows higher activation PS efficiency compared with PCN-224（Fe）after replacing Br^-in PIL（Br^-）with S₂O₈^2-by counter-anions exchange.The analysis of its catalytic degradation mechanism shows that the S₂O₈^2-concentration on the surface of PCN-224（Fe）@PIL(S₂O₈^2-)can be adjusted by the counter-anions exchange effect of PIL.The free S₂O₈^2-in solution can be effectively adsorbed through the positive charge property of PIL main chain,so that PCN-224（Fe）can activate S₂O₈^2-more easily.Therefore,PCN-224（Fe）@PIL(S₂O₈^2-)can produce better catalytic effect.（3）Preparation,properties and catalytic mechanism of MOFs@PIL（PCN-224（Fe）@PIL（Cl^-））.PCN-224（Fe）@PIL（Cl^-）composites were prepared by coating pyridine-based PIL layer on the outer surface of PCN-224（Fe）material through UV polymerization.The crystal structure,microscopic morphology and electrical properties were characterized by XRD,SEM,FT-IR and electrochemical tests.It was found that the PCN-224（Fe）@PIL（Cl^-）activated PS system exhibited better degradation effect on TC with higher activation PS efficiency than PCN-224（Fe）by directly coating pyridine-based PIL layer outside PCN-224（Fe）.The analysis of its catalytic degradation mechanism shows that the pyridine-based PIL layer can adjust the S₂O₈^2-concentration on the surface of PCN-224（Fe）@PIL（Cl^-）through the charge interaction between the PIL main chain cation and S₂O₈^2-.It can effectively adsorb the free S₂O₈^2-in solution,which makes PCN-224（Fe）easier to activate S₂O₈^2-and produce better catalytic effect.