Sorption and stability of mercury on activated carbon for emission control
Sorption and stability of mercury on activated carbon for emission control
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DOI：
10.1016/j.jhazmat.2009.02.118
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发表时间：
2009-09-15
影响因子：
13.6
通讯作者：
Jia, Charles Q.
中科院分区：
文献类型：
--
作者：
Graydon, John W.;Zhang, Xinzhi;Jia, Charles Q.
控制燃烧过程中汞排放的一项主要战略是通过注入活性炭吸附剂来去除烟气中的元素汞。在垃圾填埋场进行颗粒捕获和处置之后，捕获的汞必须永久地封存在吸附剂中。吸附汞的环境稳定性是在两种商业活性炭上测定的，一种是用气态硫浸渍的活性炭，另两种是通过与SO（2）反应而用硫浸渍的活性炭。在使用静态技术负载汞蒸气后，通过两种浸出方法表征吸附的汞的稳定性。标准毒性特征浸出程序显示，所有活性炭的浸出液浓度均远低于0.2 mg/L的限值。吸附的汞的性质进一步表征了一个连续的提取方案，特别是优化，以明确区分高度稳定的汞相。该分析表明，汞的螯合形式有两种。在相对较低温度下用气态硫浸渍的吸附剂中，汞主要以HgS存在。在其他三种吸附剂中，包括两种使用SO（2）浸渍的吸附剂，汞主要以元素形式存在，物理吸附和化学吸附到碳表面上的噻吩基团。这两种结合形式都足够稳定，可在处置后将汞永久封存在活性炭吸附剂中。(C)2009 Elsevier B. V.保留所有权利。
A leading strategy for control of mercury emissions from combustion processes involves removal of elemental mercury from the flue gas by injection of activated carbon sorbent. After particulate capture and disposal in a landfill, it is critical that the captured mercury remains permanently sequestered in the sorbent. The environmental stability of sorbed mercury was determined on two commercial, activated carbons, one impregnated using gaseous sulfur, and on two activated carbons that were impregnated with sulfur by reaction with SO(2). After loading with mercury vapor using a static technique, the stability of the sorbed mercury was characterized by two leaching methods. The standard toxicity characteristic leaching procedure showed leachate concentrations well below the limit of 0.2 mg/L for all activated carbons. The nature of the sorbed mercury was further characterized by a sequential extraction scheme that was specifically optimized to distinguish clearly among the highly stable phases of mercury. This analysis revealed that there are two forms in which mercury is sequestered. In the sorbent that was impregnated by gaseous sulfur at a relatively low temperature, the mercury is present predominantly as HgS. In the other three sorbents, including two impregnated using SO(2), the mercury is predominantly present in the elemental form, physisorbed and chemisorbed to thiophene groups on the carbon surface. Both forms of binding are sufficiently stable to provide permanent sequestration of mercury in activated carbon sorbents after disposal. (C) 2009 Elsevier B.V. All rights reserved.