Degradation Of Sulfamethoxazole In Aqueous By Activated Persulfate With Core-shell Structure CFO@COF

At present,the problem of antibiotic pollution was become more and more serious.Due to their toxicity,drug resistance and low biodegradability,antibiotics could affect the sustainable development of human health,food safety,water environment and sanitation facilities.Traditional treatment methods were difficult to remove antibiotics from water.Advanced oxidation proceses based on sulfate radicals had the advantages of high efficiency,wide p H range,strong adaptability to water quality,and easy preservation of oxidants,which had become a research hotspot in the removal of antibiotics from water in recent years.In this paper,a representative sulfonamide antibiotic,sulfamethoxazole（SMX）,was selected as the target pollutant.Co_1.2Fe_1.8O₄（CFO）was synthesized by hydrothermal method and then coated with a layer of COF material by in situ growth method to form a core-shell structure CFO@COF.The performance and catalytic mechanism of the two catalysts for activating PMS to degrade SMX before and after coating were investigated.The main research contents are as follows:（1）The CFO material was a tetragonal spinel cobalt-iron bimetallic oxide,which showed excellent activity in activating PMS.It could degrade98.2%of SMX in 30 min,at the same time,high degradation efficiency could be obtained in the p H range from weakly acidic to alkaline.The coexisting anions CO₃^2-and humic acid（HA）in the solution showed a strong inhibitory effect on the degradation effect,while Cl^-,HCO₃^-,HPO₄^2-and SO₄^2-showed the phenomenon that low concentration promoted degradation and high concentration inhibited degradation.CFO had great stability and reusability,it could still achieve more than 80%degradation rate after being reused five times.The CFO/PMS system was a system in which the free radical pathway and the non-radical pathway coexist.SO₄^·-was the main active component,and the PMS was activated by the conversion of Co and Fe valence states.（2）In order to reduce the leaching of metal ions in the material,COF material was introduced as the shell to achieve the protection of the material.CFO@COF reduced the leaching of Co and Fe while ensuring the high efficiency catalytic effect.The leaching of Co ions in the coated material was reduced from 0.74 mg·L^-l to 0.25 mg·L^-l,while the Fe ions were not leached.The effect of introducing COF material on catalyst was discussed through the characterization of CFO@COF and catalytic mechanism analysis.The excellent catalytic performance of CFO@COF might be due to the coating of COF improved the surface properties of the material,and enhanced adsorption performance of the material was more conducive to the contact between pollutants and materials.In addition,XPS and LSV analysis proved that the introduction of COF could not only reduce metal ions leaching,but also facilitate the generation of ¹O₂ and activation of PMS through electron transfer,and promote the degradation of SMX.（3）The intermediate products produced by the degradation of SMX in the CFO@COF/PMS system were analyzed and deduced,and the degradation paths were deduced.The software predicts that the degradation intermediates were less toxic to environmental aquatic organisms and have a lower risk of environmental toxicity than SMX.