Research On The Preparation Of Apatite Structural Mn₃Gd_7-xCe_x?SiO₄?₆O_1.5 And Its Catalytic Ozone Oxidation Degradation Of Antibiotics

Nowadays,the excessive antibiotic residues have been a serious problem that needs to be resolved worldwide and aroused a huge threat to countless residents and local ecosystems.Antibiotic contaminants represented by tetracycline are difficult to achieve high-efficiency degradation of tetracycline because of their broad-spectrum antibacterial properties and stable properties,etc.The heterogeneous catalytic ozone oxidation technology has the advantages of fast oxidation rate and great removal effect during the treatment of wastewater containing tetracycline,and not easy to produce secondary pollutants during the treatment process.So it has broad application prospects in antibiotic wastewater treatment.In practical applications,more and more attention has been paid to how to improve the catalytic activity of catalysts in the catalytic system and the effect of degradation treatment on pollutants,to construct a new type of highly efficient catalytic system,and to systematically study the mechanism of heterogeneous catalytic ozone oxidation technology to degrade antibiotic pollutants in water.Therefore,in this paper,a series of cerium-doped apatite-structured catalytic ozone oxidation catalysts Mn₃Gd_7-xCe_x?SiO₄?₆O_1.5 were prepared,and the catalysts were characterized using a variety of test methods,tetracycline was used as the target to be degraded,the catalytic activity of the prepared catalyst was systematically analyzed.Based on the above,the main work of this thesis is as follows:?1?In this paper,a series of novel apatite-structured catalysts Mn3Gd7-_xCe_x?SiO₄?₆O_1.5were prepared by high temperature solid-phase method based on natural apatite structure and doped with cerium?Ce?exhibited high catalytic activity.The test results showed that cerium ions were successfully doped into the apatite structure,and all the samples kept the apatite structure and no other impurities appeared.The catalyst addition can improve the removal efficiency of tetracycline in catalytic ozonation degradation tetracycline experiments.When the doping ratio of Ce is 15wt%,under the condition that the initial concentration of tetracycline is 400mg/L,the initial pH value is 3,and the dosage of catalyst is 2.5g/L,the removal rate of tetracycline can reach 83.7%after 7 minutes,and the removal rate of tetracycline can reach 99%after 60 minutes.And the catalyst also has good reuse stability.After repeated use for 5 times,the catalyst can still maintain high catalytic activity and low active ion dissolution without changing the structure.?2?The process of catalytic ozone oxidation degradation of tetracycline in this paper is more in line with the pseudo-second-order reaction kinetic model.Active radical groups play an important role in the degradation of tetracycline.Among them,·O₃ is the main effective free radical for the degradation of tetracycline,and·OH also participates in the catalytic ozonation reaction.The doping of cerium ions improves the production of oxygen vacancies on the surface of the catalyst,which in turn increases the number of active sites of the catalytic reaction and enhances the catalytic activity.On the other hand,there are positive trivalent and tetravalent positive Ce ions,Ce³⁺/Ce⁴⁺,on the other hand,there are positive trivalent and tetravalent cations Ce ions on the surface of the catalyst,and the synergy between Ce³⁺/Ce⁴⁺is beneficial to the production of free radicals and the degradation of tetracycline.During the degradation of tetracycline,many intermediate products can be found,and the intermediate products are further oxidized and decarburized to form small molecules such as water,inorganic ions,and carbon dioxide.