Removal of elemental mercury by iodine-modified rice husk ash sorbents
Pengfei Zhao , Xin Guo , Chuguang Zheng
DOI:
Received November 25, 2009,Revised August 10, 2010, Accepted , Available online
Volume 22,2010,Pages 1629-1636
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Iodine-modified calcium-based rice husk ash sorbents (I2/CaO/RHA) were synthesized and characterized by X-ray di raction, 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 Cabased
fly ash sorbents (I2/CaO/FA) and modified fly ash sorbents (I2/FA). E ects 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 e ciency 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 e ect on Hg0 capture e ciency, 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°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.
