title: Removal of elemental mercury by iodine-modified rice husk ash sorbents.
abstract: Iodine-modified calcium-based rice husk ash sorbents (I2/CaO/RHA) were synthesized and characterized by X-ray diffraction, X-ray fluorescence, and N2 isotherm adsorption/desorption. Adsorption experiments of vapor-phase elemental mercury (Hg0) were performed in a laboratory-scale fixed-bed reactor. I2/CaO/RHA performances on Hg0 adsorption were compared with those of modified Ca-based fly ash sorbents (I2/CaO/FA) and modified fly ash sorbents (I2/FA). Effects of oxidant loading, supports, pore size distribution, iodine impregnation modes, and temperature were investigated as well to understand the mechanism in capturing Hg0. The modified sorbents exhibited reasonable efficiency for Hg0 removal under simulated flue gas. The surface area, pore size distribution, and iodine impregnation modes of the sorbents did not produce a strong effect on Hg0 capture efficiency, while fair correlation was observed between Hg0 uptake capacity and iodine concentration. Therefore, the content of I2 impregnated on the sorbents was identified as the most important factor influencing the capacity of these sorbents for Hg0 uptake. Increasing temperature in the range of 80-140 degrees C caused a rise in Hg0 removal. A reaction mechanism that may explain the experimental results was presumed based on the characterizations and adsorption study.
authors.affiliation: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China. cwm1475@163.com
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhao
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Chuguang
authors.initials: C
authors.lastname: Zheng
mesh_terms: D000327:Adsorption; D007455:Iodine / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry* / Q000302:isolation & purification; D012275:Oryza
chemical_list: D007455:Iodine; D008628:Mercury