PMS协同Ce改性BiOBr材料光催化降解四环素

Photocatalytic degradation of tetracycline through PMS-assisted Ce-modified BiOBr under visible light

采用溶剂热合成法制备Ce(Ⅲ)改性BiOBr催化剂(Ce/Bi摩尔比0.1%~2%),通过XRD、SEM-mapping、XPS、UV-Vis等手段对其结构进行表征分析;以四环素为目标污染物,首次提出构建PMS/Ce(Ⅲ)改性BiOBr光催化体系降解四环素,考察催化剂种类、催化剂投加量、PMS摩尔浓度和p H等因素对反应体系降解四环素效果的影响。结果表明:Ce(Ⅲ)和Bi(Ⅲ)发生同晶置换,使得Ce(Ⅲ)改性BiOBr的最大吸收波长出现蓝移,提高光生电子和空穴的分离效率;PMS协同Ce(Ⅲ)改性BiOBr光催化降解四环素最佳条件:Ce与Bi的摩尔比为1%,投加量为1.0 g/L,PMS浓度为0.3 mmol/L,pH=9;四环素降解过程中,反应体系内主要活性物种为空穴,其贡献远高于硫酸根自由基和单线态氧。经重复利用实验证实,Ce改性BiOBr材料结构具有良好的稳定性。

The Ce(Ⅲ)modified BiOBr catalyst(Ce/Bi molar ratio 0.1%~2%)was prepared by solvothermal synthesis method,and its structure was characterized by XRD,SEM-mapping,XPS and UV-Vis.Taking tetracycline as the target pollutant,a PMS/Ce(Ⅲ)modified BiOBr photocatalytic system was proposed for the first time to degrade tetracycline.The effects of catalyst type,catalyst dosage,molar concentration of PMS and pH on the degradation of tetracycline in the reaction system were investigated.The results showed that the isomorphic substitution of Ce(Ⅲ)and Bi(Ⅲ)made the maximum absorption wavelength of Ce(Ⅲ)modified BiOBr appear blue shift,which improved the separation efficiency of photogenerated electrons and holes.The optimal conditions for photocatalytic degradation of tetracycline by BiOBr modified by PMS and Ce(Ⅲ)were as follows:molar ratio of Ce to Bi was 1%,with a dosage of 1.0 g/L and PMS of 0.3 mmol/L,at pH=9.In the process of tetracycline degradation,the main active species in the reaction system were holes,whose contribution was much higher than that of sulfate radical and singlet oxygen.It is proved that the structure of Ce modified BiOBr material has good stability by repeated utilization experiment.