| Antibiotics are widely used in human health,livestock and poultry farming.The frequent use of antibiotics not only causes their continuous detection in the water environment,but also causes the rapid spread of bacteria in the environment and the formation of bacterial resistance,indicating that antibiotics pose a major potential threat to the aquatic environment.Therefore,research and development of efficient antibiotic removal technology is a key issue in the environmental field.Persulfate oxidation is a new advanced oxidation technology that is expected to efficiently remove antibiotic contaminants due to the strong oxidizing and non-selective advantages of sulfate radicals.This subject uses an iron-based catalyst to activate sodium persulfate to oxidize sulfamerazine simulated wastewater.The effect of homogeneous Fe2+/PS system on the degradation efficiency of sulfamerazine simulated wastewater was investigated.The solid layered metal oxide catalyst MgFeCu-LDO was prepared.The factors of different metal elements ratio,aging time and calcination temperature were discussed.The crystal structure,thermal stability,specific surface area and morphology were characterized by X-ray diffractometer,thermo gravimetric analyzer,specific surface area analyzer and scanning electron microscope.The main degradation products and degradation kinetics of antibiotics were analyzed by liquid chromatography-mass spectrometry(HPLC-MS)coupled with independent reaction theory,and the degradation pathways were deduced.The main research conclusions of this paper are as follows:(1)The homogeneous Fe2+/PS system has an efficient removal effect on sulfamerazine simulated wastewater(concentration range of 2-18 mg/L).Under the optimal dosage of Fe2+and PS(0.3 mM/L,1 mM/L),the degradation rate can reach over 97%in 150 minutes.The system is suitable for a wide initial pH range(3.0-9.0),and the pH rapidly decreases to 3.0 at the beginning of the reaction and continues to the end,overcoming the disadvantages of the traditional Fenton process being limited to low pH conditions.Among them,the amount of iron added in batches can make the same amount of iron ions play a better catalytic role and improve the utilization of iron ions.Oxidation mechanism analysis showed that both·OH and SO4·-free radicals played an important role in the degradation of sulfamerazine.(2)In the homogeneous Fe2-/PS system,the presence of inorganic anions in water has different effects on the degradation of sulfamerazine.HCO3-and NO3-significantly inhibited the degradation of sulfamerazine,while NO2-had a very significant effect on the degradation of sulfamerazine.(3)The catalyst for the preparation of MgFeCu-LDO by coprecipitation method has a removal efficiency of 93.57%for the simulated wastewater of sulfamerazine.Among them,the optimal preparation conditions of the catalyst are:the molar ratio of Mg:Fe:Cu is 3:3:3,the pH value during the preparation is controlled to be between 10.5±0.2,the aging time is 24 h,and the calcination temperature is 500?.The structural analysis showed that the MgFeCu-LDO catalyst was a layered structure with characteristic peaks of hydrotalcite-like,and the maximum specific surface area of the catalyst was 74.4726 m2/g.(4)The degradation intermediates of sulfamerazine were inferred by high performance liquid chromatography-mass spectrometry.The existeince of intermediates was verified by independent reaction equations and the intermediate comoonent was determined to be 2-amino-4-phenylanino-6-methylpyrimidine.It is theoretically proved that the process of oxidative degradation of sulfamerazine by sodium persulfate conforms to the quasi-first-order kinetic mechanism,which is consistent with the experimental data kinetic analysis.In this study,the hydrotalcite-like modification was used to catalyze the oxidative degradation of sulfamerazine simulated wastewater by sodium persulfate,which provided basis data and theoretical basis for the advanced oxidation treatment of refractory organic pollutants. |
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