Study On The Performance Of Peroxymonosulfate Activated By Cobalt/titanium Dioxide In Degrading Antibiotic

The rapid development of industry,agriculture,and pharmaceuticals has drawn attention to antibiotics as widely used antibacterial drugs.The water pollution caused by their degradation metabolites has increasingly threatened the safety of human beings and aquatic organisms.Therefore,efficient removal of antibiotics from water has become an urgent issue to be addressed in water environments.Advanced oxidation processes（AOPs）are effective technologies for treating antibiotics in wastewater,characterized by the effective decomposition of organic pollutants through the production of strong oxidative free radicals.Compared with hydroxyl radical（·OH）,sulfate radical(SO₄^·-)exhibits better performance in degrading pollutants due to its better selectivity and longer half-life,so AOPs based on persulfate（PS）have been widely studied in recent years.Compared with homogeneous PS system,heterogeneous catalytic activation of PS system has the advantages of saving energy,friendly environment and convenient catalyst recovery,but the activation efficiency and degradation mechanism of different catalysts are different.Therefore,single-atom Co-TNFs and Co-TiO₂（V_O）catalysts were prepared in this paper,and the performance and mechanism of their heterogeneous catalytic activation of persulfate（PMS）for the degradation of antibiotics were investigated.The main research contents are as follows:（1）Single-atom Co-TNFs catalyst was prepared by molten salt method and used to activate PMS for the degradation of norfloxacin（NOR）.The strong metal-support interaction in molten salt environment regulates the catalytic activity and chemical selectivity of single atoms.The formation of Ti-O-Co coordination bonds and their role in promoting electron transfer between monatomic Co and the carrier interface were determined by material characterization techniques.The prepared Co-TNFs catalyst can achieve 100%NOR removal efficiency within 120 min and has good cycling stability,facilitating catalyst recovery and reuse.Quenching experiments and electron paramagnetic resonance（EPR）results showed that Co-TNFs mainly drove PMS to convert into·OH and SO₄^·-.Density functional theory calculations showed that the single atomic Co site was the active center of catalytic reaction.The p H-responsive range of this reaction system was wide,and high NOR removal rates could also be achieved in real water environments.Moreover,the environmental toxicity of the intermediate produced after the reaction was significantly reduced,indicating broad prospects for practical applications.（2）Based on the first experiment,we introduced oxygen vacancies（V_O）into titanium dioxide,and then used a molten salt method to load Co O clusters onto it to prepare Co-TiO₂（V_O）catalyst,which was applied to the performance study of activating PMS for the degradation of chloramphenicol（CP）.Compared with pure TiO₂,Co-TiO₂（V_O）catalyst showed significantly improved CP degradation performance,and can reach 100%removal efficiency within 240 min.On the one hand,the loaded Co O cluster enhance the adsorption capacity of PMS,thereby activating PMS to generate·OH and SO₄^·-.On the other hand,the presence of V_Oincreases electron density,increasing the electron transfer between the catalyst and PMS,and then activating PMS at Co active sites,improving the efficiency of degradation reaction.The Co-TiO₂（V_O）/PMS system can achieve high efficiency and complete degradation of multiple antibiotics in a short time,and exhibits high degradation performance in different actual water environments.In addition,the catalyst also has good cycling stability,facilitating catalyst separation and recovery.