School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
J Environ Sci (China). 2014 Nov 1;26(11):2257-65. doi: 10.1016/j.jes.2014.09.011. Epub 2014 Sep 20.
Elemental mercury (Hg(0)) in flue gases can be efficiently captured by mercury chloride (HgCl2) solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg(0) absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl(-) to HgCl2 is 10:1, the Hg(0) removal efficiency is the highest. Among the main mercury chloride species, HgCl3(-) is the most efficient ion for Hg(0) removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg(0) absorption reactions in the aqueous phase were investigated computationally using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3(2-) and SO2, Hg(2+) reduction occurred and Hg(0) removal efficiency decreased. The reduced Hg(0) removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCl2 solution enhanced the Hg(0) removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4(2-) and NO3(-) did not affect Hg(0) removal by HgCl2.
元素汞（Hg(0)）在烟道气中可以被氯化汞（HgCl2）溶液有效地捕获。然而，其吸收行为和影响因素仍不清楚。本文研究了 HgCl2 吸收 Hg(0)的机理以及控制去除的因素。结果表明，当 Cl(-)与 HgCl2 的摩尔比为 10:1 时，Hg(0)的去除效率最高。在主要的氯化汞物种中，当存在适量的氯离子时，HgCl3(-)是 HgCl2 吸收系统中去除 Hg(0)最有效的离子。使用 Moller-Plesset 微扰理论对水相中的 Hg(0)吸收反应进行了计算。计算得到的吉布斯自由能和能垒与实验结果非常吻合。在存在 SO3(2-)和 SO2 的情况下，发生了 Hg(2+)的还原，Hg(0)的去除效率降低。通过增加氯离子浓度，可以在一定程度上控制还原的 Hg(0)去除。HgCl2 溶液的低 pH 值提高了 Hg(0)的去除效率，在稀 HgCl2 溶液中的效果更为显著。SO4(2-)和 NO3(-)的存在并不影响 HgCl2 对 Hg(0)的去除。
