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Hg^(2+)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Hg^(2+)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(SO_2-4、NO-3、Ca^(2+)、Mg^(2+))及重金属离子等共存离子对Hg^(2+)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;SO_2-4、NO-3会抑制TMT-18和Na2S对Hg^(2+)的去除,对DTCR-2稍有促进作用;Ca^(2+)、Mg^(2+)对TMT-18去除Hg^(2+)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Hg^(2+)的去除效果,Cu^(2+)和Pb^(2+)对Hg^(2+)螯合去除效果的影响较Ni^(2+)和Zn^(2+)要大,随着Cu^(2+)和Pb^(2+)浓度的增加,DTCR-2对Hg^(2+)的去除显著降低,Cu^(2+)浓度的影响尤为显著.本研究可为解决Hg^(2+)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.
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 （ SO2- , NO3- , 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 SO2- ,NO3 concentration inhibited Hg2＋ precipitation by TMT-18 and Na2 S, 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.
出处
《环境科学学报》
CAS
CSCD
北大核心
2016年第5期1602-1607,共6页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.21277119)~~
关键词
脱硫液
重金属捕集剂
汞
共存离子
flue gas desulfurization solution
heavy metal capturing agents
mercury
co-existing ions
