Study On The Properties And Mechanism Of Selective Removal Of Heavy Metal Ions And Degradation Of Tetracycline Residues By Magnetic Ion Imprinted Photocatalyst

In recent years,water environmental problems have received wide attention in our daily life.Among them,tetracycline residues and heavy metal ions are the focus of this study.Tetracycline is widely used in human production and life,but with its abuse,it causes a large amount of tetracycline residues in the environment,which has a serious impact on the ecological environment.Photocatalytic technology is recognized as a green environmental protection technology,which can achieve high-efficiency degradation of tetracycline residues.The presence of multiple metal ions in water can hinder the selective removal of specific highly toxic heavy metal ions by various processes.Ion imprinting technology can achieve selective recognition of target heavy metal ions.Therefore,the combination of photocatalytic technology and ion imprinting technology can achieve selective removal of target highly toxic heavy metal ions simultaneously efficient degradation of tetracycline residues.Since magnetic materials can be quickly separated and improved in utilization,they are used to improve the recycling of ion imprinted photocatalysts.In this thesis,a series of magnetic ion imprinted photocatalysts were prepared by using magnetic semiconductor materials as the matrix and coating the surface with ion imprinting layer by ion imprinting technology.Through plenty of experiments,the photocatalytic degradation of tetracycline,selective removal of heavy metal ions and stability were systematically investigated.The main contents are as follows:?1?The ion imprinted Cd²⁺-CdS/Fe3O4 photocatalyst?ion imprinted CdS/Fe3O4?was prepared to study the degradation of tetracycline and the selective removal of Cd²⁺.The structure and morphology of the materials were characterized by means of XRD and TEM.The photocatalytic and selective properties of the materials were investigated by ICP and UV-Vis techniques.Due to the presence of sodium pyrrolidone carboxylate?light transmitting material?,the ion imprinted CdS/Fe3O4 can absorb most of the light.At the same time,due to the role of Fe3O4 in transferring electrons and good magnetic properties,the ion imprinted CdS/Fe3O4 exhibits excellent photocatalytic ability to degrade tetracycline and its stability,the degradation rate of tetracycline is 75.32%.In addition,the presence of a large number of imprinted cavities allows the material to have better selectivity for Cd²⁺removal.Its adsorption capacity for Cd²⁺is the highest within 1 h?154.99 mg/g?,and the ion selectivity coefficient and material selectivity coefficient are both greater than 1.?2?The ion imprinted Cr⁶⁺-ZnFe2O4 photocatalyst?ion imprinted ZnFe2O4?was prepared to study the degradation of tetracycline and the selective reduction of Cr⁶⁺.The structure and morphology of the materials were characterized by means of XRD and TEM.The photocatalytic and selective properties of the materials were investigated by ICP and UV-Vis techniques.Since 4-vp can effectively transfer electrons,the electron and hole separation rate is improved,and the material has a higher degradation rate to tetracycline,C/C0 is 0.416.Combined with the action of Cr⁶⁺imprinted cavities,the material exhibits better selective reduction performance for Cr⁶⁺.Within 2 h,the reduction rate of Cr⁶⁺can reach 92.67%,and the ion selectivity coefficient and material selectivity coefficient are both greater than 1.At the same time,due to ZnFe2O4 has magnetic properties,it can be separated and recovered to improve stability and achieve recycling.?3?The ion imprinted Cu²⁺-POPD-CoFe2O4 photocatalyst?ion imprinted POPD-CoFe2O4?was prepared to study the degradation of tetracycline and the selective reduction of Cu²⁺.The structure and morphology of the materials were characterized by means of XRD and TEM.The photocatalytic and selective properties of the materials were investigated by ICP and UV-Vis techniques.Due to the heterojunction structure formed by POPD and CoFe2O4,the separation of photogenerated electron and holes is further promoted,so that the material has higher degradation ability to tetracycline,the degree of degradation is 0.398,and better selective reduction ability for Cu²⁺.And the ion selectivity coefficient and material selectivity coefficient are both greater than 1.Meanwhile,due to the magnetic properties of CoFe2O4,the material can be effectively separated and recovered to achieve recycling.