Sequential extraction study of stability of adsorbed mercury in chemically modified activated carbons.
Sequential extraction study of stability of adsorbed mercury in chemically modified activated carbons.
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DOI：
10.1021/es201399d
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发表时间：
2011-08
影响因子：
11.4
通讯作者：
S. Tong;M. Fan;Lei Mao;C. Jia
中科院分区：
文献类型：
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作者：
S. Tong;M. Fan;Lei Mao;C. Jia
用硫和溴进行化学改性的活性炭在捕获煤燃烧和其他工业烟气中的蒸汽汞方面具有更大的有效性。废活性炭中捕获汞的稳定性决定了汞的最终归宿，是制定汞控制策略的关键。然而，它仍然是一个很大程度上未知的主题，特别是对br处理的活性炭。采用六步顺序提取程序，本研究评估了四种活性炭、一种褐煤衍生活性炭和三种经Br(2)、KClO(3)和SO(2)化学处理的汞的浸出潜力。结果清楚地表明，Br-和SO(2)-处理对捕获的汞的稳定性有积极的影响。溴化活性炭捕获的汞非常稳定，可能以溴化汞络合物的形式存在。硫在高温下与SO(2)一起加入，能够通过形成硫化物和可能的磺酸盐螯合物来稳定大部分汞。然而，硫酸盐的存在使捕获的一小部分汞（<10%）在温和条件下不稳定。用KClO(3)处理活性炭降低了捕获汞的总体稳定性，首次观察到汞稳定性与负载温度呈正相关。
Activated carbons chemically modified with sulfur and bromine are known for their greater effectiveness in capturing vapor Hg from coal combustion and other industrial flue gases. The stability of captured Hg in spent activated carbons determines the final fate of Hg and is critical to devising Hg control strategy. However, it remains a subject that is largely unknown, particularly for Br-treated activated carbons. Using a six-step sequential extraction procedure, this work evaluated the leaching potential of Hg captured with four activated carbons, one lignite-derived activated carbon, and three chemically treated with Br(2), KClO(3), and SO(2). The results demonstrated clearly the positive effect of Br- and SO(2)-treatment on the stability of captured Hg. The Hg captured with brominated activated carbon was very stable and likely in the form of mercurous bromide complex. Sulfur added at high temperature with SO(2) was able to stabilize a majority of Hg by forming sulfide and possibly sulfonate chelate. The presence of sulfate however made a small fraction of captured Hg (<10%) labile under mild conditions. Treating activated carbon with KClO(3) lowered the overall stability of captured Hg. A positive dependence of Hg stability on Hg loading temperature was observed for the first time.