Synthesis Of Ag₃PO₄/perovskite Nanocomposite And Its Capacity Of Photocatalytic Degradation Of Bisphenol A Under Visible Light

Bisphenol A?BPA?is a representative environmental endocrine disruptor,with the extensive use of BPA into the environment,has resulted the water pollution problems become increasingly serious.The BPA exhibits the hydrophobic and nondegradable properties,and the traditional wastewater treatment method is difficult to achieve its effective degradation,but the photocatalytic technology is known as a promising one for it can complete degradation and mineralize most of organic pollutants without secondary pollution by using the sunlight as the excitation energy,which will replace the traditional treatment technology and has become a new trend.Silver orthophosphate?Ag₃PO₄?,attracted significant attentions due to its good photocatalytic performance using visible light,and exhibited high quantum efficiency,narrow band gap widths and strong oxidizing ability.However,Ag₃PO₄ is slightly soluble in water and unstable in light,which will prone to photocorrosion,and its specific surface area is also small,which are severely limited its practical application.Perovskite style oxide?ABO₃?has flexible element composition,and good thermal stability,optical,electrical and magnetic properties,is more efficient and stable catalytic materials.Herein,in this study,novel visible-light-driven materials Ag₃PO₄/LaCoO₃ and Ag₃PO₄/LaCo_1-xBi_xO₃ were prepared to improve the defects of Ag₃PO₄.And then,the photocatalytic activity and the photocatalytic mechanisms of the BPA been investigated.The main contents and conclusions are as follows:?1?Novel LaCoO₃ and LaCo_1-xBi_xO₃were prepared based on the critic acid method.And then the liquid deposition method was used to prapare the visible-light-driven materials Ag₃PO₄/LaCoO₃ with varying LaCoO₃ content and Ag₃PO₄/LaCo_1-xBi_xO₃ with varying Bi content.The surface morphology,crystal structure,physical and chemical properties,and light absorption characteristics were detected by means of analyses.The results show that the addition of LaCoO₃ or LaCo_1-xBi_xO₃ can significantly increase the stability of Ag₃PO₄ in the composites and the specific surface area,enhance the absorption range of light and the separation rate of photogenerated electron-hole pairs.?2?The BPA was degraded by Ag₃PO₄/LaCoO₃ or Ag₃PO₄/LaCo_1-xBi_xO₃ under visible light.And the BPA was completely removed after the irradiation for 40 min and 77.27% and 80.71%of the total organic?TOC?was removed,respectively.The degradation rate of BPA in Ag₃PO₄/LaCoO₃?Ag₃PO₄/LaCo0.5Bi0.5O₃ photocatalytic system is 0.0831 min^-1?0.09944 min^-1,which is 3.022 and 3.616 times of pure Ag₃PO₄,respectively.?3?The photocatalytic degradation of BPA with Ag₃PO₄/LaCo0.5Bi0.5O₃ composite photocatalysts were screened through the P-B design.The main influence factors were optimized by BBD design.The results show that: the amount of catalyst concentration,BPA concentration and light intensity are the main factors that influence the removal rate of BPA.The optimal experimental conditions for the amount of catalyst concentration is 0.78g/L,BPA concentration is 8.72mg/L,light intensity of 384.23 W,and under these conditions,the prediction of BPA removal rate could reach to 100%,TOC removal rate reaches 87.21%,the experimental values are close to the predicted values?BPA removal rate: 99.53%;TOC removal rate: 86.32%?.?4?After three recycling runs,the degradation of BPA in the two kinds of composite photocatalytic materials system still kept high photocatalytic activity and mineralization ability.The results demonstrate the composite materials are relatively stable than pure Ag₃PO₄ and ease the photocorrsion of Ag₃PO₄ in a certain extent.?5?The free radical trapping experiments revealed that all the active species in the degradation of BPA.It was found that the activespecies of superoxide radical?O2·-?,hydroxyl radicals?·OH?and photogenerated hole?h+?participated in the degradation of BPA,in which photogenerated holes have the greatest effect on the photocatalytic oxidation process.