The Preparation Of MIL-53(Fe) Modified By Manganese Ion And Its Catalytic Performance On Tetracycline

With the widespread use and massive discharge of tetracycline antibiotics,causing serious damage to the water environment,the efficient removal of tetracyclines from water bodies is great importance to the protection of the environment.Advanced Oxidation Process（AOPs）is an effective way to degrade antibiotic contaminants,AOPs has the advantages of high efficiency,low cost and simple operation,which can generate free radicals with strong oxidizing through transition metal activated permonosulfate（PMS）.The preparation of porous materials containing transition metals plays an important role in the activation of PMS.Metal-organic frameworks（MOFs）are formed from metal centers and organic ligands,it has the advantages of excellent water stability and easy modification,MOFs have great potential for the activation of PMS.However,its catalytic capacity is limited when dealing with refractory antibiotic contaminants.In order to obtain MOFs based catalyst with better catalytic performance,it is necessary to modify them.Based on this,MIL-53（Fe）was modified by doping manganese ion in this study.The catalytic performance of Mn-doped MIL-53（Fe）and the catalytic degradation mechanism of tetracycline were investigated.The details of the study were as follows:（1）Mn-MIL-53（Fe）with different manganese ion doping amounts was synthesized by one-step solvothermal method,and the surface morphology and chemical structure of Mn-MIL-53（Fe）were characterized by SEM,XRD,FT-IR,BET,XPS and ESR.Mn-MIL-53（Fe）was applied to activate PMS for the removal of tetracycline from water.The removal efficiency of Mn-MIL-53（Fe）was higher than that of monomer,and the maximum removal efficiency can reach 93.2%.（2）The effect of the dosage of PMS and catalyst on TC removal efficiency were investigated.When the dosage of PMS and Mn-MIL-53（Fe）were 0.3 g/L and 0.2 g/L,respectively,the best degradation effect of TC was obtained.（3）The effect of Mn-MIL-53（Fe）on the removal efficiency of TC was investigated under the conditions of different initial p H,different concentrations of coexisting anions(Cl^-,CO₃^2-,SO₄^2-)and humic acid.Meanwhile,the effect of different temperatures on the catalytic degradation of TC was investigated.The results showed that the catalytic degradation of TC was endothermic reaction,and the calculated activation energy of the reaction was 4.629 k J/mol.（4）Combined with the experimental study of free radical capture and ESR characterization results,the main active radicals involved in the degradation process of TC were SO₄·^-and·OH.（5）Through the analysis of ESR characterization and XPS characterization,the possible mechanism of catalytic activation of PMS by Mn-MIL-53（Fe）to degrade TC was investigated.（6）Based on LC-MS analysis,the degradation intermediates of TC in Mn-MIL-53（Fe）/PMS system were investigated,their possible chemical structures were deduced,and the potential degradation pathways of TC were further analyzed.（7）The cyclic performance of the Mn-MIL-53（Fe）/PMS system for TC degradation was investigated,and the stability of Mn-MIL-53（Fe）/PMS system was determined by ICP.Furthermore,the effect of the Mn-MIL-53（Fe）/PMS system on the removal efficiency of TC in tap water,Xiangjiang River water and medical wastewater was investigated.