Chi Yao, Yan Naiqiang, Qu Zan, Qiao Shaohua, Jia Jinping
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
J Hazard Mater. 2009 Jul 30;166(2-3):776-81. doi: 10.1016/j.jhazmat.2008.11.130. Epub 2008 Dec 11.
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.
为了促进烟气中单质汞（Hg(0)）的脱除，使用碘作为氧化剂将Hg(0)转化为氧化态或颗粒结合态。研究了在各种条件下通过均相气相反应和涉及颗粒的非均相反应脱除Hg(0)的情况，并开发了一种测试涉及颗粒反应动力学的方法。发现碘对Hg(0)氧化有效，在393 K时二级反应速率常数约为7.4(±0.2)×10⁻¹⁷ cm³·分子⁻¹·s⁻¹。一氧化氮对Hg(0)氧化的均相气相反应有显著抑制作用。在飞灰或粉末活性炭存在下，碘对Hg(0)的氧化可大大加速。SO₂在涉及颗粒的反应中略微降低了Hg(0)的脱除效率。据估计，向含有20 g/m³飞灰的烟气中添加0.3 ppmv碘时，Hg(0)的脱除效率高达70%。此外，如果向含有飞灰的烟气中注入10 mg/m³活性炭和0.3 ppmv碘，预测Hg(0)的脱除效率高达90%。结果表明，碘与飞灰和/或活性炭的组合可有效提高燃煤烟气中Hg(0)的脱除率。
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