氯盐对汞化合物污染土壤热脱附过程的影响

Influence of Chlorine Salt on Soil Contaminated with Mercury Compounds during Thermal Desorption Process

    摘要
  • 摘要: 对HgCl2、HgS、Hg(NO3)2·H2O、HgO、HgSO4 5种试剂分别添加MgCl2、CaCl2和NaCl 3种氯盐,采用热重分析法进行热挥发性对比研究,以期选择对汞化合物热脱附有促进作用的氯盐,并将其添加到内蒙古2块不同污染场地的汞污染土壤样品(A、B)中,进行低温热脱附修复研究. 结果表明:5种汞化合物试剂热脱附温度由低到高依次为HgCl2＜HgS＜Hg(NO3)2·H2O＜HgO＜HgSO4. 在汞化合物中加入MgCl2、CaCl2和NaCl后的热重分析发现,MgCl2对HgS、Hg(NO3)2·H2O、HgO、HgSO4热脱附过程影响最大,降低了汞化合物热脱附的初始温度. A、B 2个污染土壤样品加入MgCl2热脱附后,汞的去除率分别从无药剂处理的65.67%、70.74%升至81.35%、84.91%. 表明MgCl2可以促进汞污染土壤中汞化合物的转化,有利于土壤汞污染的热脱附修复,应用前景较好.

     

    Abstract: To investigate the thermal volatility of mercury compounds, thermogravimetric analysis (TGA) associated with MgCl2, CaCl2 and NaCl was respectively performed on five inorganic mercury compound reagents:HgCl2, HgS, Hg(NO3)2·H2O, HgO and HgSO4. The most conducive chlorine salt was selected and then added into soils from two different contaminated sites in Inner Mongolia for low temperature thermal desorption (LTTD). The results showed that the increasing order of temperature of desorption was as follows:HgCl23)2·H2O4. After MgCl2, CaCl2 and NaCl were added into mercury compounds, the thermal desorption of the compounds was impacted most by MgCl2 through TGA, and the initial temperature of thermal desorption of the mercury compounds was reduced. After treatment with MgCl2, the removal rate of mercury in the two samples was enhanced from 65.67% to 81.35% and from 70.74% to 84.91%, which indicates that MgCl2 can promote the transformation of mercury compounds in contaminated soils and is beneficial to the thermal desorption repair of mercury contaminated soils. Thus, it has a promising prospect for application.

     

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