| With the increasing production and usage of antibiotics,the problem of antibiotic pollution in water is becoming more and more serious.Antibiotics entering natural water will induce the emergence of drug-resistant bacteria and drug-resistant genes,which will threaten the life and health of human beings and other organisms.Therefore,how to effectively remove antibiotics from water has become one of the key problems urgently to be solved in water environment.Norfloxacin(NOR)is difficult to be photolyzed and biodegraded due to its stable structure composed of aromatic ring and heteroatom.Advanced oxidation technology can catalyze the degradation of antibiotics with the help of strong oxidizing free radicals generated.Among them,Fenton-like method has attracted more attention due to its wide application range of p H and difficulty in causing secondary pollution.The key of Fenton-like technology is to research and develop efficient and stable catalysts.The metal-organic framework Fe-MIL-101 has a promising potential in the removal of organic pollutants due to its rich pore size,large specific surface area,abundant iron sites and high chemical stability.However,due to the high price of its metal sites and the fact that most of them are covered by ligands,the activation efficiency of H2O2 is low.Therefore,this study improves the activation capacity of Fe-MIL-101 for H2O2 by optimizing the coordination structure of iron,so as to realize the efficient and stable degradation of antibiotics in water.The main research contents are as follows:1.Fe/Ce-MIL-101 with electronic distribution asymmetry on degradation and mechanism of NOR.We synthesized the bimetallic organic framework Fe/Ce-MIL-101by introducing the metal ion Ce during the synthesis process,and constructed the Fe-O-Ce asymmetric coordination structure.The asymmetry of the coordination structure will lead to the non-uniform distribution of electrons,which will enhance the affinity between Fe/Ce-MIL-101 and H2O2.In addition,Fe/Ce-MIL-101 had more electron transfer numbers between the active Fe site and H2O2 than Fe-MIL-101.The results showed that Fe/Ce-MIL-101 degradation efficiency of NOR reached 94.8%within 60min,and it could be completely removed after 180 min,and the removal of TOC also reached 66.2%.According to the calculation results and degradation sampling tests,NOR was mainly carried out by piperazine ring opening and aldehyde ketone conversion in the Fe/Ce-MIL-101/H2O2 reaction system,and the remaining intermediates had little toxic effect on the environment after the treatment.In addition,the catalyst has high stability,and the degradation efficiency does not decrease significantly after 5 cycles.Excitingly,this catalyst has a high removal rate for both bisphenol A and sulfamethazine,and also maintains a high removal rate for NOR in actual wastewater.Therefore,this catalyst has great potential for practical application.2.H2 reduced oxygen vacancy-rich FeII/FeIII-MIL-101 on degradation and mechanism of NOR.A highly efficient catalyst Fe-MIL-101-H-220 containing mixed valence FeII/FeIII and defects was obtained by simple heat treatment of Fe-MIL-101 in H2atmosphere.NOR can be completely removed by this catalyst within 80 min.And the change of the initial p H of the solution is not very obvious,so it can be applied to a wide range of p H.In addition,FeII/FeIII-MIL-101 also has good stability,with a removal efficiency of 93.5%after 5 cycles.Similarly,this defective mixed valence catalyst also showed high degradation performance for bisphenol A,sulfadimidine and rhodamine B.The highly efficient degradation performance of this catalyst is mainly due to the site exposure caused by heat treatment and·OH produced by the rapid interaction between FeII site and H2O2 generated by thermal reduction.Moreover,oxygen vacancy also plays an important role.This electron-rich site can not only activate H2O2,and the reduction of FeIII to FeII can also be accelerated by electron transfer to the FeIII site.Under the synergistic action of the active metal site and oxygen vacancy,FeII/FeIII-MIL-101obtained excellent degradation performance. |
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