State Key Laboratory of Heavy Oil Processing, Beijing Key Lab of Oil & Gas Pollution Control, China University of Petroleum, Beijing, 102249, China; College of Chemical Engineering and Environment, China University of Petroleum, Beijing, 102249, China.
State Key Laboratory of Heavy Oil Processing, Beijing Key Lab of Oil & Gas Pollution Control, China University of Petroleum, Beijing, 102249, China; College of Chemical Engineering and Environment, China University of Petroleum, Beijing, 102249, China.
Environ Res. 2020 Jul;186:109582. doi: 10.1016/j.envres.2020.109582. Epub 2020 Apr 24.
Heavy-metal contaminated soils post great environmental and health concerns. In this study, Cr and Cd which are frequently observed in contaminated soils, were selected as representatives of hazardous heavy metals because of their different redox potentials and electric charges. Cr(VI)-, Cd(II)-, Cr(VI)/Cd(II)-contaminated soils were remediated in two-chamber air-cathode MFCs, in order to investigate the remediation of soil contaminated by single heavy metal and mixed heavy metals. Four ion exchange membranes (IEMs) were first evaluated to find out that bipolar membrane (BPM) was able to well maintain pH in both anolyte and catholyte, which was beneficial to support biological metabolism and heavy metal removal. It was also found that heavy metal ions (Cr, Cd or Cr/Cd) could migrate toward the cathode forming a concentration gradient under the weak electric field. The interaction between negatively charged Cr and positively charged Cd had no major effect to hinder each other on the migration, suggesting that the reduction reaction and electric field should be the main motivation for metal ion migration. The remediation performance of mixed heavy metal contaminated soil was superior to that of single heavy metal contaminated soil, for the possible reason of smaller internal resistance under mixed heavy metal condition.
重金属污染土壤引起了严重的环境和健康问题。在本研究中，选择了经常在污染土壤中观察到的 Cr 和 Cd 作为危险重金属的代表，因为它们具有不同的氧化还原电位和电荷。为了研究单一重金属和混合重金属污染土壤的修复，在双室空气阴极 MFC 中修复了 Cr(VI)-、Cd(II)-、Cr(VI)/Cd(II)-污染的土壤。首先评估了四种离子交换膜（IEM），发现双极膜（BPM）能够很好地维持阳极和阴极中的 pH 值，这有利于支持生物代谢和重金属去除。还发现，在弱电场下，重金属离子（Cr、Cd 或 Cr/Cd）可以向阴极迁移，形成浓度梯度。带负电荷的 Cr 和带正电荷的 Cd 之间的相互作用对彼此的迁移没有重大影响，这表明还原反应和电场是金属离子迁移的主要动力。混合重金属污染土壤的修复性能优于单一重金属污染土壤，这可能是由于混合重金属条件下的内部电阻较小。
