Photocatalytic removal of elemental mercury via Ce-doped TiO2 catalyst coupling with a novel optical fiber monolith reactor.

Reduction of mercury emission from coal combustion is a serious task for public health and environmental societies. Herein, Ce-doped TiO2 (Ce/TiO2) catalyst coupling with a novel optical fiber monolith reactor was applied to efficiently remove elemental mercury (Hg(0)) from coal-fired flue gas. Under the optimal operation condition (i.e., 1.5 mW/cm(2) UV light, 90 degrees C), above 95% of Hg(0) removal efficiency was attained over the optical fiber monolith reactor coating with 3.40 g/m(2) Ce/TiO2 catalyst. The effects of flue gas compositions on Hg(0) removal performance were clarified systematically. Gaseous O2 replenished the surface oxygen, hence maintaining the production of free radicals and promoting the removal of Hg(0). SO2, HCl, and NO inhibited Hg(0) removal in the absence of O2 due to the competitive adsorption and consumption of free radicals. However, SO2 and HCl significantly enhanced Hg(0) removal with the participation of O2, while NO exhibited obviously inhibitory effect even with the assistance of O2. H2O also decreased the Hg(0) oxidation capacity owing to the competitive adsorption and reduction of HgO. The optical fiber monolith reactor exhibited much superior Hg(0) removal capacity than the powder reactor. Utilization of Ce/TiO2 catalyst coupling with an optical fiber monolith reactor provides a cost-effective method for removing Hg(0) from coal-fired flue gas.