Removal of elemental mercury by photocatalytic oxidation over La2O3/Bi2O3 composite


Jun Cai , Renjun Li , Yanan Zhou , Xueqian Wang , Langlang Wang , Ping Ning , Lei Tao

DOI:10.1016/j.jes.2020.09.037

Received June 15, 2020,Revised , Accepted September 26, 2020, Available online October 22, 2020

Volume 102,2021,Pages 384-397

La2O3/Bi2O3 photocatalysts were prepared by impregnation of Bi2O3 with an aqueous solution of lanthanum precursor followed by calcination at different temperatures. The composite materials were used for the first time for the photocatalytic removal of Hg0 from a simulated flue gas under UV light irradiation. The results showed that the sample containing 6 wt.% La2O3 and calcined at 500°C has the highest dispersion of the active sites, which was promoted by the strong interaction with the support (i.e., the formation of Bi-O-La species). Since they are fully accessible on the surface, the material also exhibits excellent optical properties while the heterojunction formed in La2O3/Bi2O3 promotes the separation and migration of photoelectron-hole pairs and thus Hg0 oxidation efficiency is enhanced. The effects of the various factors (e.g., the reaction temperature and composition of the simulated flue gas (i.e., O2, NO, H2O, and SO2)) on the efficiency of the Hg0 photocatalytic oxidation were investigated. The results demonstrated that O2 and SO2 enhanced the efficiency of the reaction while the reaction temperature, NO, and H2O had an inhibitory effect.

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