| 17a-ethynylestradiol(EE2)is a widely used synthetic estrogen,which can cause disturbance of human endocrine system and nervous system.EE2 is ubiquitous in environmental waters,which poses a serious potential health threat to human beings.It is an important and challenging task to find an efficient and rapid method for the degradation of EE2.Among the various removal methods,photocatalytic technology attracts wide attention in the field of water pollution treatment since it is a green and efficient method.In this paper,the AgI/BiOBr and BiOBr/BiOI heterojuntion photocatalysts was synthesized by simple method.The chemical composition,micromorphology and optical properties of the prepared samples were characterized by XRD,SEM,TEM,XPS,BET,UV-vis DRS,PL and other detection techniques.The two catalysts were used for photodegradation of EE2 under the visible light,their photocatalytic properties were evaluated was evaluated and the mechanism of its photocatalytic process was analyzed.The main research contents were as follows:1.The Agl/BiOBr photocatalyst was successfully prepared by solvothermal-precipitation method.By comparing the structural characterization and EE2 degradation performance of the prepared photocatalysts,the synthesis conditions for AgI/BiOBr were optimized as follows:the hydrothermal temperature was 145?,the hydrothermal time was 18h and the molar ratio of Ag/Bi was 1:2.Under the optimal photodegradation conditions(AgI/BiOBr dosage was 0.5 g/L,pH value of EE2 solution was 5.8),the optimal 1:2 AgI/BiOBr catalyst has a high degradation efficiency for EE2.After 12 minutes of visible light irradiation,the degradation rate of 3 mg/L EE2 reached 99.5%.The reaction rate of the optimal 1:2 AgI/BiOBr photocatalyst was 138.7 and 16.0 times higher than those of pure BiOBr and Agl,respectively.AgI/BiOBr photocatalyst has good stability and can be recycled many times.The results of capture experiments and energy band calculations showed that AgI/BiOBr was a Z-type heterojunction photocatalyst.In the photocatalytic reaction,the role of active species is h+>·O2->·OH.The mechanism of degradation of EE2 is Z-type charge transfer and separation.The formation of heterojunction decreased the recombination rate of electrons(e-)and holes(h+)and improved its photocatalytic activity significantly.2.The BiOBr/BiOI photocatalyst was successfully prepared by mild and easy one-step co-precipitation at room temperature.The optimum preparation conditions were as follows:Br/I molar ratio was 1:1,solvent ratio(ethylene glycol:ultrapure water)was 3:1.The optimal BiOBr/BiOI was used to decompose 3 mg/L of EE2 under visible light.When the dosage of BiOBr/BiOI was 0.5 g/L and the pH value of EE2 solution was 5.8,the degradation rate of EE2 by the optimal BiOBr/BiOI photocatalyst reached 100%after 9 minutes of visible light irradiation.The reaction rate of the optimal BiOBr/BiOI photocatalyst was 396 and 3.4 times higher than those of the pure BiOBr and BiOI photocatalysts,respectively.The PL analysis results showed that the formation of BiOBr/BiOI heterojunction promoted the separation of electrons and holes,which greatly improved the photodegradation efficiency of BiOBr/BiOI heterojunction.Based on capture experiment and energy band calculation,the reaction mechanism of BiOBr/BiOI photocatalyst was discussed.The main active species in the photocatalytic reaction were identified as h+ and ·O2-.3.The prepared AgI/BiOBr and BiOBr/BiOI photocatalysts were compared with the photocatalysts reported in the literature.In the application of visible light degradation of EE2,both AgI/BiOBr and BiOBr/BiOI exhibited superior photocatalytic performance than the reported photocatalysts,which have both high removal rate and high photocatalytic reaction speed.Compared with AgI/BiOBr,BiOBr/BiOI has an attractive application prospect in the rapid removal of organic pollutants and has more prominent advantages in industrial applications since its synthetic route realized the green chemistry concept. |
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