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首页> 外文期刊>Environmental Science & Technology >Speciation, Characterization, and Mobility of As, Se, and Hg in Flue Gas Desulphurization Residues
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Speciation, Characterization, and Mobility of As, Se, and Hg in Flue Gas Desulphurization Residues

机译：烟气脱硫残渣中As，Se和Hg的形态，特征和迁移率

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Flue gas from coal combustion contains significant amounts of volatile toxic trace elements such as arsenic (As), selenium (Se), and mercury (Hg). The capture of these elements in the flue gas desulphurization (FGD) scrubber unit has resulted in generation of a metal-laden residue. With increasing reuse of the FGD residues in beneficial applications, it is importantto determine metal speciation and mobility to understand the environmental impact of its reuse. In this paper, we report the solid phase speciation of As, Se, and Hg in FGD residues using X-ray absorption spectroscopy (XAS), X-ray fluorescence spectroscopy (XRF), and sequential chemical extraction (SCE) techniques. The SCE results combined with XRF data indicated a strong possibility of As association with iron oxides, whereas Se was distributed among all geochemical phases. Hg appeared to be mainly distributed in the strong-complexed phase. XRF images also suggested a strong association of Hg with Fe oxide materials within FGD residues. XAS analysis indicated that As existed in its oxidized state (As(Ⅴ)), whereas Se and Hg was observed in primarily reduced states as selenite (Se(Ⅳ)) and Hg(Ⅰ), respectively. The results from the SCE and variable pH leaching tests indicated that the labile fractions of As, Se, and Hg were fairly low and thus suggestive of their stability in the FGD residues. However, the presence of a fine fraction enriched in metal content in the FGD residue suggested that size fractionation is important in assessing the environmental risks associated with their reuse.
机译：燃煤燃烧的烟气中含有大量的挥发性有毒微量元素，例如砷（As），硒（Se）和汞（Hg）。这些元素在烟气脱硫（FGD）洗涤塔中的捕集已导致产生了金属残留物。随着在有益应用中烟气脱硫残留物的再利用不断增加，确定金属的形态和迁移率以了解其再利用对环境的影响非常重要。在本文中，我们使用X射线吸收光谱（XAS），X射线荧光光谱（XRF）和顺序化学萃取（SCE）技术报告了FGD残留物中As，Se和Hg的固相形态。 SCE结果与XRF数据相结合表明，As与氧化铁缔合的可能性很大，而Se分布在所有地球化学相中。汞似乎主要分布在强复合阶段。 XRF图像还表明，汞与FGD残留物中的Fe氧化物材料密切相关。 XAS分析表明，As以氧化态存在（As（Ⅴ）），而Se和Hg分别以亚硒酸盐（Se（Ⅳ））和Hg（Ⅰ）的主要还原态存在。 SCE和可变pH浸出测试的结果表明，As，Se和Hg的不稳定部分相当低，因此表明它们在FGD残留物中的稳定性。但是，FGD残渣中富含金属含量的细小颗粒的存在表明，分级分离对于评估与其再利用相关的环境风险很重要。

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