| In recent years,with the increasingly widespread use of tetracycline antibiotics,the problem of environmental pollution caused by tetracycline antibiotics has become increasingly prominent,which has become one of the problems that environmental workers pay more attention to.Because tetracycline antibiotics have very good water solubility,they can exist and spread in large quantities for a long time after entering the environmental water body,which can seriously threaten the health and safety of human beings,animals and plants.Among many water treatment technologies,the advantage of persulfate advanced oxidation method is increasingly prominent.The sulfate free radical produced by persulfate advanced oxidation method has strong oxidizability and excellent degradation effect on high concentration organic matter.However,persulfate alone does not have strong oxidizability and needs to be activated.Therefore,it is necessary to choose an economic and applicable activation method.It has practical significance for the application of persulfate advanced oxidation process.In order to solve the above problems,the red mud was reused as the carrier of transition metal,and the catalyst which can activate persulfate efficiently was prepared.The degradation efficiency of high concentration tetracycline antibiotic wastewater was studied.The research results can provide technical reference for the effective treatment of tetracycline antibiotic wastewater.The preparation method and conditions of chlortetracycline were studied in this paper.The apparent morphology and structure properties of the catalyst were analyzed by characterization and analysis.The results show that the catalyst prepared by coprecipitation and over impregnation method has better catalytic performance.The orthogonal experiment is used to optimize the preparation conditions of the catalyst.The results show that the optimal preparation conditions of Co-RM catalyst are: the solution concentration is 0.1mol/L,The calcination time is 2h and calcination temperature is 400℃;The optimum conditions for preparation of Cu-RM catalyst are: solution concentration is 0.05mol/L,calcination time is 2h,calcination temperature is 300℃.The results of the characterization also show that cobalt and copper are successfully loaded on the surface of red mud,and the catalyst can effectively activate persulfate.The degradation efficiency of aureomycin is affected by many factors.The influencing factors are studied by using the control variable method.The experimental system of this project is 100 m L.The 0.04g/L（0.05g/L）Co-RM（Cu-RM）catalyst is used to activate 0.3g/L（0.2g/L）persulfate,and 95% of the initial concentration of aureomycin can be degraded within 90 minutes.The degradation efficiency of chlortetracycline in the system increased with the increase of catalyst dosage,the increase of persulfate dosage and the increase of reaction temperature,and the degradation efficiency decreased with the increase of initial concentration of aureomycin.pH has a very obvious effect on the degradation of chloramphenicol.When pH=5,the reaction system has the best removal efficiency,and acid and alkaline conditions can inhibit the oxidation ability of the reaction system.The concentration of anions Cl-,HCO3-,H2PO4- and HA in water will affect the degradation efficiency of aureomycin.The higher the concentration,the lower the degradation efficiency of aureomycin.Considering the complexity of water environment in practical application,the removal of chlortetracycline from wastewater was studied.It was found that various organic and inorganic compounds in the actual wastewater would affect the reaction,but the overall degradation rate was relatively high.In the recycling experiment,Co-RM（Cu-RM）can still maintain a certain catalytic activity after four times of recycling.In the fourth degradation experiment,the removal efficiency of chlortetracycline can reach more than 80%.In order to determine the main active substances in the reaction system,methanol and tertbutyl alcohol were added to identify the types of free radicals produced in the reaction system,and the free radicals were captured by electron spin resonance spectroscopy（ESR）.The experimental results show that the main active substance in the oxidation system is sulfate radical,and a small amount of hydroxyl radical is produced to assist the oxidation.The intermediate products produced in the degradation process of chlortetracycline were analyzed by high performance liquid chromatography-mass spectrometry.Chlortetracycline mainly changed into water,carbon dioxide,ammonium and other inorganic substances through dechlorination,double bond breaking,ring opening,ring removing and so on,which realized the mineralization process of chlortetracycline. |
