Author(s): Chi Y, Yan N, Qu Z, Qiao S, Jia J
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Abstract In order to facilitate the removal of elemental mercury (Hg(0)) in flue gas, iodine was used as the oxidant to convert Hg(0) to the oxidized or particulate-bound form. The removal of Hg(0) by the homogenous gas phase reaction and the heterogeneous particle-involved reactions was investigated under various conditions, and a method to test the particle-involved reaction kinetics was developed. Iodine was found to be efficient in Hg(0) oxidation, with a 2nd-order rate constant of about 7.4(+/-0.2)x10(-17)cm(3)molecules(-1)s(-1) at 393 K. Nitric oxide showed significant inhibition in the homogenous gas reaction of Hg(0) oxidation. The oxidation of Hg(0) with iodine can be greatly accelerated in the presence of fly-ash or powder activated carbon. SO(2) slightly reduced Hg(0) removal efficiency in the particle-involved reaction. It was estimated that Hg(0) removal efficiency was as high as 70\% by adding 0.3 ppmv iodine into the flue gas with 20 g/m(3) of fly-ash. In addition, the predicted removal efficiency of Hg(0) was as high as 90\% if 10mg/m(3) of activated carbon and 0.3 ppmv iodine were injected into the flue gas with fly-ash. The results suggest that the combination of iodine with fly-ash and/or activated carbon can efficiently enhance the removal of Hg(0) in coal-fired flue gas.
This article was published in J Hazard Mater
and referenced in International Journal of Waste Resources