Preparation of BiOBr/Bi2O2CO3 Heterojunction by Chemical Etching and its Efficient Removal of Hg0
To enhance the utilization rate of BiOBr for visible light and improve its photocatalytic activity,p-n type BiOBr/Bi2O2CO3 heterojunction photocatalysts were prepared by a simple chemical etching method,and the performance of elemental mercury(Hg0)removal under fluorescent lamp(FSL)was carried out.The physical and chemical properties of photocatalysts were analyzed by various characterization techniques to clarify the charge separation and transfer process at the surface or interface of the composites.The results showed that the mercury removal efficiency of the as-prepared Bi2O2CO3-3 photocatalyst could reach as high as 95％.The removal performance of Bi2O2CO3-3 photocatalyst was significantly inhibited by SO2,but the removal efficiency could be restored when SO2 was stopped.Fluorescent lamp irradiation was very important for photocatalytic process.In the strong alkaline environment,the excess OH-would react with the hole(h+)generated by FSL light,which slightly affected the mercury removal efficiency of BiOBr/Bi2O2CO3.It was found that the heterojunction formation between BiOBr and Bi,O,CO3 could reduce the recombination of photogenerated electrons and holes,and improve their photocatalytic performance.The mechanism analysis exhibited that the O2-and h+were the main active species,while·OH was not involved in the photocatalytic Hg0 removal process.
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