• 关键词：脱硫液  重金属捕集剂  汞  共存离子

• 基金项目：国家自然科学基金(No.21277119)

• 童新
• 1. 台州科技职业学院, 台州 318020;2. 浙江大学环境工程系, 杭州 310058

• 沃静静
• 浙江大学环境工程系, 杭州 310058

• 孙明洋
• 浙江大学环境工程系, 杭州 310058

• 汤婷媚
• 浙江大学环境工程系, 杭州 310058

• 陆荣杰
• 浙江大学环境工程系, 杭州 310058

• 徐新华
• 浙江大学环境工程系, 杭州 310058

• 摘要：利用湿法烟气脱硫技术(Wet Flue Gas Desulfurization, WFGD)同步除汞被认为是最经济的燃煤烟气脱汞方式,但进入脱硫液的Hg²⁺易被还原并再次释放进入大气,造成二次污染.针对这一问题,本研究选择了常用的Na₂S、三巯基均三嗪三钠盐(TMT)、二硫代氨基甲酸盐(DTC)等系列重捕剂,考察了投加量对Hg²⁺去除效果的影响,并筛选出了去除效果较好的3种类型重捕剂,探究了脱硫液中主要的阴阳离子(SO₄^2-、NO₃^-、Ca²⁺、Mg²⁺)及重金属离子等共存离子对Hg²⁺去除效果的影响.结果表明:Na₂S、TMT类重捕剂TMT-18和DTC类重捕剂DTCR-2的去除效果相对较好;SO₄^2-、NO₃^-会抑制TMT-18和Na₂S对Hg²⁺的去除,对DTCR-2稍有促进作用;Ca²⁺、Mg²⁺对TMT-18去除Hg²⁺有促进作用,而对Na₂S有抑制作用;重金属离子会抑制重捕剂对Hg²⁺的去除效果,Cu²⁺和Pb²⁺对Hg²⁺螯合去除效果的影响较Ni²⁺和Zn²⁺要大,随着Cu²⁺和Pb²⁺浓度的增加,DTCR-2对Hg²⁺的去除显著降低,Cu²⁺浓度的影响尤为显著.本研究可为解决Hg²⁺在脱硫液中的还原再释放及二次污染问题,同时也为湿法烟气脱硫同时脱汞的工业应用提供理论依据.

• Abstract：Wet flue gas desulfurization (WFGD) system used for sulfur dioxide (SO₂) is proved to be effective for the co-removal of mercury (Hg) in coal-fired power plants. However, it may result in secondary atmospheric pollutions caused by the reduction of Hg²⁺ to Hg⁰. In this paper, Na₂S, 2, 4, 6-trimercaptotiazine, trisodium salt nonahydrate (TMT-18) and sodium dithiocarbamate (DTC) were selected to precipitate aqueous Hg²⁺ in simulated desulfurization solutions. Moreover, the effects of co-existing ions (SO₄^2-, NO^3-, Ca²⁺, Mg²⁺ and heavy metal) on Hg²⁺ stabilization was investigated. DTCR-2, TMT-18, Na₂S were found to be better in Hg²⁺ removal. The increment of SO₄^2-、NO₃^- concentration inhibited Hg²⁺ precipitation by TMT-18 and Na₂S, but it was beneficial for DTCR-2 to remove Hg²⁺. The Hg removal efficiency was increasing with the increment of Ca²⁺ and Mg²⁺ concentration except Na₂S. The increment of heavy metals concentration inhibited Hg²⁺ precipitation efficiency to a considerable extent, especially Cu²⁺. Our results would provide theoretical basis for the co-removal of highly soluble oxidized Hg in the wet FGD systems.

• Key words：flue gas desulfurization solution  heavy metal capturing agents  mercury  co-existing ions

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