Degradation Of Antibiotics In Water By Oxone Reagent Activated By Cobalt-Based Catalytic Materials

Antibiotics released into the environment can cause chemical contamination and produce resistant microorganisms and resistant genes,which can enter the human body through direct or indirect contact and pose a serious threat to human health.However,general treatment methods often fail to remove antibiotics at the root.Therefore,it is crucial to investigate a novel advanced oxidation technology based on the activation of persulfate by catalytic materials to generate sulphate radicals(SO₄^·-)for the treatment of antibiotic wastewater.In this study,the cobalt-based catalytic materials CoTiO₃and CoFe₂O₄were prepared,and the crystalline structure,specific surface area（BET）,thermogravimetric-differential thermal（TG-DTG）,Raman spectroscopy（Raman）and X-ray photoelectron spectroscopy（XPS）of the materials were investigated by controlling various conditions in combination with X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FT-IR）,specific surface area（BET）,thermogravimetric-differential thermal（TG-DTG）,Raman spectroscopy（Raman）and X-ray photoelectron spectroscopy（XPS）Characterisation was carried out to investigate the effects of the material’s crystal structure,surface morphology,specific surface area and other characteristics,and to determine the optimal preparation conditions;and to activate potassium persulphate（Oxone）with it to produce oxidising·OH and SO₄^·-radicals for the degradation of tetracycline antibiotics（TCs）in water.The optimum removal conditions were determined by adjusting the amount of materials,Oxone concentration,initial concentration of antibiotics,solution p H and temperature;finally,the mechanism of Oxone activation for antibiotic degradation by each material was revealed based on free radical scavenging experiments.The main studies and conclusions are as follows:（1）CoTiO₃materials were prepared by hydrothermal synthesis method,and it was determined that the CoTiO₃prepared at a molar ratio of 3:1 of raw material citric acid to tetrabutyl titanate,hydrothermal reaction at 160°C for 24 h and calcination at 600°C for6 h had the best performance.Oxone activation with CoTiO₃resulted in 95%,94%and99%removal for 20 mg/L of tetracycline,oxytetracycline and chlortetracycline wastewater,respectively.After three cycles of experiments,the removal rates were still86%,78%and 67%,respectively.In addition,the mechanism of activation of Oxone by CoTiO3 to degrade antibiotics was revealed:the reaction in the CoTiO₃/Oxone system was carried out on the surface of the material,and the activation of Oxone by the low valent state Co²⁺produced the strong oxidative radical SO₄^·-.（2）CoFe₂O₄magnetic materials were prepared by hydrothermal synthesis,which improved the material activation performance and separation and recycling.The optimum performance of the prepared CoFe₂O₄was determined by hydrothermal reaction at 180°C for 12 h and calcination at 500°C for 3 h.Oxone activation with CoFe₂O₄resulted in 96%,94%and 92%removal for 20 mg/L tetracycline,oxytetracycline and aureomycin wastewater treatment,respectively.After three cycles of experiments,the removal rates were still 76%,68%and 79%,respectively.In addition,the mechanism of activation of Oxone by CoFe₂O₄for the degradation of antibiotics was revealed.In the CoFe₂O₄/Oxone system,both low valence Co²⁺and Fe²⁺could activate Oxone to produce SO₄^·-,which improved the material activation performance.（3）The CoFe₂O₄magnetic material was prepared by ball milling,which reduced particle agglomeration and increased the effective active sites of the material.The optimum performance of CoFe₂O₄prepared by calcination at 500°C for 3 h after a ball milling time of 4 h was determined.Oxone activation with CoFe₂O₄resulted in 98%,92%and 92%removal for 20 mg/L of tetracycline,oxytetracycline and aureomycin wastewater,respectively.After three cycles of experiments,the removal rates were still76%,63%and 79%,respectively.In addition,the mechanism of activation of Oxone by CoFe₂O₄for the degradation of antibiotics was revealed.Compared with the CoFe₂O₄prepared by hydrothermal method,the CoFe₂O₄prepared by ball milling method has better activation performance and degradation efficiency.