Study On Cobalt Ferrite Composite Fiber Membrane And Its Pollutant Degradation Performanc

Solar energy is the most widespread,primitive and accessible energy source on earth.In today’s increasingly severe environmental situation and more urgent energy problems,photocatalytic degradation of pollutants using solar energy as a driver has become one of the most promising environmental technologies.Cobalt ferrate（CoFe₂O₄）has a forbidden band width of 1.4 e V and has more suitable conduction band and valence band positions,with a large photoresponse range and high efficiency;copper oxide（Cu₂O）is a cheap and easily available non-toxic and non-hazardous photocatalytic material with a forbidden band width of 2.4 e V,while a single CoFe₂O₄ or Cu₂O has limitations as a monolithic catalyst,for this reason,we modified these two monolithic catalysts.The two monolithic catalysts were modified in the expectation of exploring for the improvement of photocatalytic materials.To this end the main studies and conclusions of this thesis are as follows:（1）Z-scheme g-C₃N₄/CoFe₂O₄ heterojunction nanofiber membrane materials were successfully prepared by a combination of electrostatic spinning and hydrothermal methods.The best degradation performance of the material for pollutants was found for a doping ratio of 1:0.05 between g-C₃N₄ and CoFe₂O₄.Compared with the single catalysts g-C₃N₄and CoFe₂O₄,the photocatalytic efficiencies of the composite catalysts were improved by3-fold and 2.3-fold for tetracycline and 4.6-fold and 3.8-fold for methylene blue,respectively.The degradation efficiencies of g-C₃N₄/CoFe₂O₄ heterojunction for tetracycline and methylene blue reached 86%and 96%,respectively,within 120 min.The successful synthesis of g-C₃N₄/CoFe₂O₄ heterojunctions was determined using XRD,PL,UV-vis,EIS,XPS and other characterization tools,which confirmed the successful broadening of their light absorption range.（2）The reaction mechanism in the photocatalytic process of g-C₃N₄/CoFe₂O₄heterojunction was investigated.The reactive species playing a major role in the reaction were examined using electron paramagnetic resonance（EPR）and radical capture experiments,and it was concluded that superoxide radical(·O^2-)was the main reactive oxide in the catalytic process.Combined with the XPS valence band low test and various characterizations,the surface reaction mechanism of g-C₃N₄/CoFe₂O₄ heterojunction was constructed.（3）The ortho-octahedral type cuprous oxide（Cu₂O）crystals were prepared using a liquid-phase reduction method with glucose as the reducing agent,and the Cu₂O crystals prepared at the optimal temperature condition（80°C）for photocatalytic performance were compounded with MXene in the Cu₂O preparation process,and the PL photoluminescence performance of the materials was evaluated.The results showed that the intensity of Cu₂O photoluminescence became significantly weaker after MXene addition,i.e.,the photogenerated carrier activity became stronger.the Cu₂O/MXene catalyst was stronger than that with a single catalyst to degrade 20 mg^-1 methyl orange,and the degradation efficiency could reach 89%within 120 min.In this paper,two different composite catalysts with electrostatic spinning,hydrothermal synthesis,and solvent reduction were selected as the main preparation techniques around the theme of photocatalysis for the degradation of pollutants such as methylene blue,tetracycline,and methyl orange.Further reference is provided for the research direction of photocatalysis.