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

La 2 O 3 /Bi 2 O 3 photocatalysts were prepared by impregnation of Bi 2 O 3 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 Hg 0 from a simulated flue gas under UV light irradiation. The results showed that the sample containing 6 wt.% La 2 O 3 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 La 2 O 3 /Bi 2 O 3 promotes the separation and migration of photoelectron-hole pairs and thus Hg 0 oxidation efficiency is enhanced. The effects of the various factors (e.g., the reaction temperature and composition of the simulated flue gas (i.e., O 2 , NO, H 2 O, and SO 2 )) on the efficiency of the Hg 0 photocatalytic oxidation were investigated. The results demonstrated that O 2 and SO 2 enhanced the efficiency of the reaction while the reaction temperature, NO, and H 2 O had an inhibitory effect.