Study On The Layered Double Hydrotalcite And Its Derivatives To Activate Persulfate To Degradate Acid Red 27 Wastewater

With the development of printing and dyeing industry and food industry,more and more dye wastewater is produced,which not only pollutes the water environment,but also poses a threat to human health.How to degrade dye molecules economically and efficiently has become a concern.Persulfate oxidation technology has attracted more and more attention from the society because of its wide application range of p H and strong oxidizability.Choosing appropriate catalysts to improve the degradation rate and improve the degradation effect is the focus of research.Layered double hydroxides（LDH）can be used as an efficient catalyst in advanced oxidation systems due to its characteristics of carrying a variety of metal elements and large specific surface area.Therefore,in this paper,LDH was used as an activator to activate peroxymonosulfate（PMS）to degrade dye wastewater,and azo dye acid red 27（AR27）was used as a model pollutant to study the degradation performance,influencing factors and activation mechanism of LDH and its derivatives activated PMS.The paper mainly includes the following three aspects:（1）In the first part,binary cobalt-iron LDH was prepared by a double-drop co-precipitation method.The large specific surface area of LDH can expose more active sites to activate PMS to efficiently degrade AR27.The performance of different catalyst systems was compared,and it was found that cobalt-iron LDH had stronger performance.The effects of different operating parameters on the degradation performance were also investigated.Through radical quenching experiments and EPR tests,it was proved that there were SO₄^·-,·OH radicals and ¹O₂ non-radicals.The intermediate products of AR27 degradation were analyzed and deduced,and a possible degradation mechanism was proposed.（2）In the second part,the zeolite imidazolate framework material ZIF-67（Co）was selected as the template and hollow polyhedron cobalt-iron LDH（HP-Co Fe-LDH）was grown in-situ by using sacrificial template method.The morphology,structure and performance of HP-LDH were analyzed by material characterization tests,and the effects of HP-LDH on the catalytic performance under different solution concentration ratios were compared,as well as other operating parameters on the degradation performance.It was found that HP-LDH not only had high degradation effect but also good recycling performance.And a possible degradation mechanism was proposed.（3）In the third part,a novel p-n heterojunction LDH@LFO was constructed by combining the photocatalytic material lanthanum ferrite（LFO）with Co Fe-LDH,which was applied in the photocatalytic assisted PMS activation system.The materials were analyzed by morphological structure characterization and photoelectrochemical tests.LDH@LFO was used as the major research object to explore the degradation effect of Vis/LDH@LFO/PMS system on AR27.It was found that the effect of combined photocatalysis and PMS activation was better than that of single photocatalysis and PMS activation.The effects of LDH@LFO with different operating parameters on degradation performance were compared.It can be found that LDH@LFO not only has efficient degradation effect but also has good recycling performance.Combined with catalyst characterization,degradation experiments and EPR tests,the possible degradation mechanism was inferred.