Design Of Supported Iron-based Heterogeneous Fenton Catalysts And Their Catalytic Performance

Efficient removal of organic pollutants is a very important issue in the field of wastewater treatment.Heterogeneous Fenton technology provides an efficient way to degrade organic pollutants in wastewater.However,most developed Fe-based heterogeneous Fenton catalysts are faced with problems such as slow Fe³⁺/Fe²⁺cycling,limited interfacial electron transport rate,low catalytic efficiency under neutral pH conditions.Therefore,the research was focused on solving above problems in the traditional Fe-based heterogeneous Fenton catalysts.The aim of dissertation is to construct highly efficient and stable heterogeneous Fenton catalysts through controlling the metal composition and the support of the catalyst.Azo dyes acid Orange ? was chosen as the model pollutant to evaluate the performance of catalysts.Fe⁰-Fe₂O₃ nanoparticles supported on ordered mesoporous carbon?Fe⁰-Fe₂O₃/OMC?as a composite heterogeneous Fenton catalyst was firstly synthesized by using ammonia-atmosphere post-impregnation and carbothermal reduction strategy.Fe⁰-Fe₂O₃/OMC possesses ordered mesoporous structure with high surface area and pore volume,uniform mesopore,highly dispersed and tiny Fe⁰-Fe₂O₃ active species.Fe⁰-Fe₂O₃/OMC exhibits significantly superior catalytic performance than Fe⁰/OMC and Fe₂O₃/OMC under nearly room temperature and neutral conditions.The enrichment of ordered mesoporous carbon and the synergistic effect between Fe⁰ and Fe₂O₃ can accelerate the cycling of Fe³⁺/Fe²⁺ and enrich catalytic sites.The reaction efficiency is greatly improved both in the initial and catalytic stage.To further improve the catalytic efficiency and pH adaptive capacity of iron based catalyst,the iron-copper bimetallic nanoparticles supported on hollow mesoporous silica spheres as a composite catalyst?FeCu/HMS?was prepared by introducing Cu species.The catalyst possesses a typical hollow mesoporous structure and highly dispersed iron-copper nanoparticles in the matrix of HMS.Moreover,FeCu/HMS exhibits significantly superior catalytic performance than FeCu/MS,Fe/HMS and Cu/HMS under nearly room temperature and neutral conditions.The cycling of the F³⁺/Fe²⁺ and Cu²⁺/Cu⁺ redox couples can be effectively improved by the synergistic effect between iron and copper in the composite catalyst.The hollow structure of the catalyst can also provide more available active sites and promote the mass transfer in catalytic reaction,which could greatly improve the reaction efficiency.Based on the above research,a series of iron-copper bimetallic nanoparticles with different ratios of Fe to Cu supported on hollow mesoporous silica spheres composite catalysts was constructed by controlling the adding amounts of iron salts and copper salts.The optimal mass ratio of Fe to Cu is proved to be 2:6.The composite catalyst further shows the potential in treatment of high concentration dye.The synergistic effect between iron and copper in the catalyst is derived from the acceleration of the interfacial electron transfer in the redox cycles of Fe³⁺/Fe²⁺and Cue+/Cu+ pairs.To accelerate the electron transfer rate in the catalysis reaction,the iron-copper bimetallic nanoparticles supported on carbon nanofibers as a composite catalyst?FeCu/CNF?was fabricated by electrospinning technique.The iron-copper bimetallic nanoparticles were formed in situ by carbothermic reduction during the carbonization process.FeCu/CNF possesses fibrous morphology,porous structure and highly dispersed iron-copper nanoparticles.More importantly,FeCu/CNF exhibits significantly superior catalytic performance to FeCu/C,Fe/CNF and Cu/CNF under nearly room temperature and neutral conditions.The cycling of the Fe 3+/Fe2+ and Cu²⁺/Cu⁺redox couples can be greatly promoted by the synergistic effect between iron and copper in the composite catalyst.The nanofibrous structures of catalyst could also enhance catalytic activity because of their high axial ratio aspect,which allow a fast and long-distance electron transport and then promote the kinetics of electron transfer during the catalytic reaction.Based on the above structural advantages,the catalytic activity of FeCu/CNF catalyst was greatly improved.This research develops new materials and technology for the efficient removal of organic pollutants.It can also provide pathway and theoretical foundation for the design and application of heterogeneous Fenton catalysts,which has promising scientific significance and application prospects.