Copper Oxide And Its Composite Oxide Activate Peroxodisulfate To Degrade Antibiotic Pollutants In Water

Advanced oxidation processes（AOPs）based on SO₄·^-have attracted more and more attention due to their high efficiency and adaptability to the degradation of organic pollutants.Because of their high activity,stability and easy regeneration and recovery,transition metal oxides are often used as heterogeneous catalysts to activate persulfate（Persulfate,PS）to degrade organic pollutants.In recent years,CuO and its composite oxides have become a popular heterogeneous catalyst for PS activation due to their advantages such as low energy consumption,low p H adjustment cost and high treatment efficiency under neutral conditions.In this paper,CuO with different morphologies and composite oxides of CuMn and CuZr were synthesized by different methods as heterogeneous catalysts to activate PS to degrade organic pollutants in water.Under neutral conditions,high removal rate of organic pollutants and low leaching rate of Cu²⁺were achieved.The relationship between the structure and properties of the catalyst and the activated PS performance was further studied,and the degradation mechanism of pollutants was discussed,the specific research contents of this paper are summarized as follows:（1）In this chapter,four kinds of CuO samples with different morphologies were synthesized by hydrothermal method,calcination method and water bath method,and they were used to activate PS in the presence of bicarbonate to remove three kinds of organic pollutants in water.The relationship between the surface properties of CuO and the activation pathway and efficiency of PS was studied,and the key active species for degradation of pollutants were determined.The results show that the bicarbonate-CuO-PS system can not only effectively degrade organic pollutants,but also further mineralize them.The activated PS produced by non free radical pathway should be the main reaction species to remove pollutants.Cu²⁺with more electronic defects should be the active site of PS production.The synthesis of Cu²⁺and/or CuO with large surface area should be an effective method to promote the formation of activated PS.In addition,a new method is developed to semi quantitatively analyze the amount of activated PS,which provides a strong technical support for the study of non free radical activation of PS.（2）In this chapter,a series of Mn-doped CuO samples were prepared by hydrothermal method and used to remove ofloxacin by PS activation.The relationship between their surface properties and catalytic performance was studied,and the key parameters affecting the degradation of pollutants were discussed,and the optimal degradation conditions were found.The results showed that CM3 sample（Cu:Mn=6:1）showed the highest degradation activity of ofloxacin at neutral p H,which was due to its high adsorption capacity to ofloxacin and high activity to PS non free radical activation,which was conducive to the surface reaction between them.The large surface area of CM3 and the uncharged surface at neutral p H promote the adsorption of ofloxacin,and≡Cu²⁺with relatively high surface electron density may be the reason for producing activated PS.Because ofloxacin is mainly degraded by activated PS,the common ions in water have little effect on the process.Toxicity evaluation showed that the treated ofloxacin solution was harmless.Finally,the cyclic experiments show that CM3 is a stable and effective catalyst for PS non free radical activation.（3）In this chapter,Zr doped CuO samples（CZ）were successfully prepared by precipitation calcination method,which showed that activated PS had higher activity of removing Cefalexin than pure CuO.The effects of different reaction conditions on the degradation process were studied,and the optimum conditions were found.The doping of Zr increases the pore size and specific surface area of the samples,and its special surface structure leads to its special adsorption properties.CZ showed a high activity of degrading Cefalexin at neutral alkaline p H,under this condition,Cefalexin was easily adsorbed on the catalyst surface and was more easily attacked and degraded by active species.The common ions Mg²⁺and HCO₃^-in actual water slightly inhibit the degradation rate of cephalexin,but have little effect on the degradation efficiency.EPR and free radical scavenging experiments showed that Cefalexin was mainly degraded by SO₄·^-and·O₂^-while·OH and ¹O₂ only played an auxiliary role.The results of the cyclic experiment show that CZ is a stable and effective heterogeneous catalyst.