可见光协同钴铈铁氧体高效活化过一硫酸盐降解噻虫胺

Visible Light Combined with Cobalt-Cerium Ferrite to Activate Persulfate for Clothianidin Degradation

采用溶胶-凝胶燃烧的方法,将Co掺入到CeFeO_(3)(CFO)钙钛矿晶格中,制备了具有晶格缺陷的CeFe_(0.8)Co_(0.2)O_(3)(CFCO)纳米颗粒催化剂,并考察了其光催化活化过一硫酸盐(PMS)降解噻虫胺(CTD)的性能和活化机理。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等表征技术对CFCO催化剂进行表征分析,结果表明,在CFCO上形成了表面氧空位(V_(O))。同时,还研究了过一硫酸盐用量、不同pH值对CFCO降解噻虫胺的影响。结果表明,在CFCO投加量为0.6 g/L、PMS用量为0.8 mmol/L、pH值为7时,20 mg/L的噻虫胺在30 min内完全降解。并且经过4次循环使用后,噻虫胺降解率仍能达到91.2%。CFCO对于PMS的高效活化能力,主要归功于晶格缺陷所产生的电位差促使自由电子顺着氧空位快速定向传导到PMS上。为了模拟在天然水体环境中CFCO光催化活化PMS去除CTD,进行阴离子和有机酸的对比实验,分析了不同环境因素对CFCO降解噻虫胺的影响;此外,通过自由基淬灭实验与电子自旋共振(ESR)检测确定了CFCO光催化活化PMS降解噻虫胺实验中起主要作用的活性物种为单线态氧(^(1)O_(2))与羟基自由基(·OH),并分析推测了自由基的产生机理。最后采用高效液相色谱-质谱联用仪(LC-MS)检测了CTD降解过程中可能产生的代谢产物,并基于代谢产物的产生顺序归纳出了三条可能的降解路径。研究结果表明,CFCO催化剂在可见光照射下能够高效活化PMS,从而迅速降解水体中的噻虫胺,为铁氧体材料降解新烟碱农药提供了一条可行的方案。

CeFe_(0.8)Co_(0.2)O_(3)(CFCO)nano-particle catalyst with lattice defects was prepared by incorporating Co into CeFeO_(3)(CFO)perovskite lattice by sol-gel combustion method.The performance and activation mechanism of CFCO photocatalytic activation of peroxymonosulfate(PMS)for the degradation of clothianidin(CTD)were investigated.The catalyst was characterized by XPS,XRD,SEM,TEM and other characterization techniques and the result showed that surface oxygen vacancies(V_(O))were formed on CFCO.Furthermore,the effects of potassium peroxymonosulfate dosage and pH on the degradation of CTD by CFCO were also investigated.The results showed that 20 mg/L clothianidin was completely degraded under 0.6 g/L CFCO and_(0.8)mmol/L PMS in pH=7 within 30 min.And the degradation rate of clothianidin still reached 91.2%after four times of recycling.The highly efficient activation of CFCO for PMS was mainly attributed to the potential difference created by the lattice defects,which drived the rapid directional conduction of free electrons down the oxygen vacancies to PMS.Meanwhile,in order to simulate the removal of CTD by CFCO photocatalytic activation of PMS in natural water environment,comparative experiments with anionic and organic acids were performed.The influence of different environmental factors on the degradation of clothianidin by catalyst were analyzed.In addition,it was determined that the active oxygen free radicals that played the main role in the experiment of degrading clothianidin by photocatalytic activation of PMS were ^(1)O_(2) and·OH through radical quenching experiment and ESR detection,and the corresponding mechanism of free radicals generation was analyzed and speculated.The possible metabolites in the degradation of CTD were analyzed by high performance liquid chromatography-mass spectrometry(LC-MS),and three possible degradation paths were summarized based on the order of metabolites produced.The results showed that CFCO catalyst effectively activated PMS and degraded clothianidin under visible light irradiation,which can provide a feasible scheme for ferrite materials to degrade neonicotinoid pesticides.