Study On Degradation Of Tetracycline In Water By Uv Fenton And Activated Persulfate

In recent years,the rapid development of the economy has significantly improved human living standards,but with it,important enterprises such as medical,aquaculture,and chemical industries have produced a large amount of antibiotics on a daily basis,which has had a serious impact on people’s living environment,especially the water environment.Nowadays,tetracycline antibiotics have become the second most commonly used antibiotics in the world,and they are difficult to efficiently remove by traditional sewage treatment plants.Due to the complex structure and difficulty in degradation of tetracycline,its residue in the aquatic environment exceeds the standard,which has a significant impact on the ecological environment.This type of water body has become a difficult problem in water treatment and a hot research topic for scholars.The topic is to use tetracycline(C₂₂H₂₄N₂O₈)antibiotics as the target pollutant for advanced oxidation treatment of wastewater containing tetracycline.and determine the optimal treatment conditions through experiments.The experiment used UV Fenton and activated persulfate systems to study the degradation of tetracycline production wastewater.In the Fenton stage of ultraviolet light,a single factor influence experiment was used.Using hydrogen peroxide（H₂O₂）as the oxidant and ferrous sulfate heptahydrate（Fe SO₄·7H₂O）as the catalyst,assisted by ultraviolet light at a wavelength of 254nm,the entire reaction system was placed in a dark box.The optimal reaction conditions have been determined:when the initial yield of tetracycline is 100μmol/L,n(Fe²⁺):n（H₂O₂）=1:12,p H=3,reaction temperature is 40℃,and reaction time is 60minutes,the final tetracycline removal rate reaches over 92.5%.The reaction process was confirmed to be highly efficient,with degradation concentrated in the first 30minutes.During the activation of persulfate,ultraviolet light irradiation with a wavelength of 254nm was used as the catalytic condition,and thermal activation was used as the catalytic condition to activate persulfate.Potassium persulfate（K₂S₂O₈）was used as the oxidant to explain the target pollutant tetracycline.In the UV activation reaction,the concentration of tetracycline in the reaction system is 50μmol/L When the molar concentration ratio of oxidant to tetracycline is 200:1 and p H=4,the removal rate can reach over 90%after 120minutes of reaction at a fixed temperature of 20℃.In the thermal activation reaction,when an equal amount of tetracycline is added to the control system,the molar concentration ratio of oxidant to tetracycline is 200:1,p H=4,and the reaction temperature is 70℃for 120minutes,the removal effect of tetracycline is the best,and the tetracycline removal rate can reach over 99%.Considering the high energy consumption when the temperature reaches 70℃,a combination of ultraviolet light activation and thermal activation of persulfate was used to study the degradation effect by reducing the temperature and increasing ultraviolet light irradiation.Finally,it was determined that at 50℃,the molar concentration ratio of oxidant to tetracycline was 200:1,and the removal rate could reach a separate thermal activation degradation level by reacting at p H=4 for 120minutes.On the basis of response surface methodology,Box Behnken model was used to optimize the experimental design of thermally activated persulfate system,and a quadratic polynomial regression equation with removal rate as the response value,reaction temperature,molar concentration ratio of oxidant to tetracycline,and p H as independent variables was constructed.The optimal reaction conditions were determined to be 60℃and a molar ratio of 200:1,The optimal degradation effect can reach 99.93%when p H=4.Through comprehensive analysis of the degradation rate,feasibility,and economy of the UV Fenton and activated persulfate methods,it is found that the activated persulfate system has better removal efficiency and operability than the UV Fenton method.After detection,there are many intermediate products in the degradation of tetracycline by the UV thermal activation system.Therefore,the possible structure of the intermediate products of tetracycline is speculated and the degradation process is briefly analyzed.Obtaining effective treatment methods and optimal treatment conditions can provide theoretical support for antibiotic water treatment.