硫代硫酸盐浸提法修复汞污染土壤及含汞浸出液的光分解回收处理  

Remediation of mercury contaminated soil with thiosulfate solution washing followed by photo-decomposing and separating mercury from washing solution

作　　者：畅永锋 梁鹏 路殿坤 谢锋 CHANG Yongfeng;LIANG Peng;LU Diankun;XIE Feng(School of Metallurgy,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学冶金学院,沈阳110819

出　　处：《环境工程学报》2020年第12期3527-3533,共7页Chinese Journal of Environmental Engineering

基　　金：国家自然科学基金资助项目(51374054)。

摘　　要：汞污染土壤对环境的危害巨大,已成为国内外主要关注的环境问题之一。以某PVC化工厂附近的含汞土壤样品为研究对象,开展了硫代硫酸盐浸提脱汞的研究,对浸提前后的含汞土壤开展了Förstner七步顺序提取实验,考察分析了含汞土壤及浸提后土壤中汞的存在形态,并对含汞的硫代硫酸盐浸出液开展了紫外光分解、沉淀脱除汞的研究。结果表明:该土壤样品中含汞总量高达2400 mg·kg^−1;其中41.3%的Hg以水溶态、交换态、盐酸溶态和硝酸溶态形式存在,属于易释放汞;以有机质结合态和硫化态形式存在的Hg分别占33.9%和24.2%,属于稳定形态的汞。以硫代硫酸钠为浸出剂,可以有效地浸出含汞土壤中的易释放形态汞;采用0.01 mol·L^−1的硫代硫酸钠溶液,在室温下浸出约6 h,可将含汞土壤中95%以上的易释放汞浸提出来,浸提后土壤中残余的汞基本上仍以有机质结合态和硫化态形式存在。对含汞11.6 mg·L^−1的硫代硫酸盐浸出液,经254 nm的紫外线照射5 min,即可将99.1%以上的汞-硫代硫酸盐络合物分解转变为稳定的硫化汞沉淀,从而将汞从浸出液中分离回收。本研究表明,硫代硫酸盐浸提处理及采用紫外光分解分离回收汞可从含汞土壤中分离除去易释放形态汞。Mercury polluted soil and related risk to the environment and human health have presented a significant concern in China and globally.In this study,the mercury contaminated soil samples from the field near a PVC factory were taken as the research object to conduct thiosulfate based Hg-washing tests.For the soil samples before and after washing,the seven steps sequential extraction tests based on Förstner methods were conducted to identify the responding Hg-species existing in these two kinds of samples.The Hg-pregnant solution was subjected to ultra-violent light exposure,photo-decomposing the Hg-thiosulfate complex and mercury removal by precipitatation.The experimental results showed that the total mercury concentration was 2400 mg·kg^−1 in the contaminated soil,and 41.3%of Hg was water-soluble,ion-exchangeable,HCl^-soluble,and HNO3-soluble forms which belonged to easy-released Hg-species.The organic-bound Hg and sulfide-bound Hg accounted for 33.9%and 24.2%,respectively,which belonged to the stable forms.The sodium thiosulfate solution was an effective lixiviant for the easy-released mercury in the polluted soil.About 95%of the easyreleased mercury could be washed out by 0.01 mol·L^−1 sodium thiosulfate within six hours at room temperature.The residue mercury in the washed soil was remained as the organic-and sulfide-bound forms.For the washing solution containing 11.6 mg·L^−1 mercury,99.1%of the Hg-thiosulfate complexes could be decomposed and precipitated as black-HgS after exposing under 254 nm UV light for five minutes,then the mercury could be separated and recovered acccordingly.The thiosulfate based washing followed by separating mercury from the pregnant washing solution with UV light photolysis is a potential remediation method for the removal of easyreleased mercury from the contaminated soil.This result can provide reference for the treatment of mercury in soil.

关 键 词：汞 硫代硫酸盐 浸提 光分解 顺序提取 汞形态 

分 类 号：X53[环境科学与工程—环境工程]