高锰酸钾氧化-电动强化修复Cr(Ⅲ)污染土壤

Potassium permanganate oxidation-electrokinetic advanced remediation for soils contaminated with trivalent chromium

铬渣污染土壤中三价铬[Cr(Ⅲ)]比例较高,为解决常规电动修复方法对Cr污染土壤中Cr(Ⅲ)去除效率低的问题,提出了高锰酸钾氧化-电动强化修复技术。以配制的Cr(Ⅲ)污染高岭土和国内某铬渣污染场地土壤为研究对象,施加1 V·cm-1直流电压,采用阴极添加KMn O4溶液的形式氧化Cr(Ⅲ),试验运行96 h。试验结果表明:通过高锰酸钾氧化,高岭土配土组的总铬去除效率从对照组的32.4%提高到78.4%,铬渣污染土壤组从对照组的20.9%提高到42.6%,添加KMn O4溶液浓度增加,去除效率提高。在电场作用下,阴极加入的高锰酸钾以阴离子形式在土壤中向阳极迁移,Cr(Ⅲ)以阳离子形式向阴极迁移,部分Cr(Ⅲ)形成沉淀吸附在土壤中。高锰酸钾迁移过程中把部分Cr(Ⅲ)氧化为六价铬[Cr(Ⅵ)],Cr(Ⅵ)以含氧阴离子的形式向阳极迁移,Cr(Ⅵ)迁移性好于Cr(Ⅲ),有效控制了Cr(Ⅲ)形成沉淀,从而促进Cr的去除。研究表明,高锰酸钾氧化-电动强化修复技术能显著提高铬的去除效率。

The proportion of trivalent chromium[Cr（Ⅲ）] is higher in soils contaminated with chromium residues. The potassium perman-ganate（KMn O4）oxidation-electrokinetic advanced remediation method was proposed as a means to overcome the low Cr（Ⅲ）removal efficiency of the conventional electrokinetic method for the remediation of chromium-contaminated soil. A voltage of 1 V·cm-1 DC was applied together with the addition of KMn O4 into the cathode for the advanced remediation of simulated Cr（Ⅲ）-contaminated Kaolin as well as chromium residue-contaminated soils collected from a chemical factory in China. Experiments were run for 96 hours. The total chromium[ Cr（T）] removal efficiency was significantly enhanced by the（KMn O4）oxidation-electrokinetic advanced remediation method, and the Cr（T） removal rate of the groups with KMn O4 oxidation was up to 78.4% and 42.6%, as compared with 32.4% and 20.9% for the control groups without KMn O4 oxidation, for the simulated Cr（Ⅲ）-contaminated Kaolin（32.4%）and chromium residue-contaminated soils, re-spectively. The Cr（T） removal rate enhancement increased with the increasing KMn O4 concentration. Under the direct electric field, the Mn O-4 added in the cathode moved toward the anode, and the Cr（Ⅲ）positive ions migrated toward the cathode through the soils; some Cr（Ⅲ）ions were adsorbed on the soils by precipitation during migration. The other Cr（Ⅲ）ions were oxidized to hexavalent chromium [Cr（Ⅵ）]ions during KMn O4 migration, and the Cr（Ⅵ）negative ion migrated toward to the anode. Because the migration rate of Cr（Ⅵ）ions was higher than that of Cr（Ⅲ）ions in the soils, the precipitation of Cr（Ⅲ）ions could be controlled effectively, and the chromium removal efficiency could be improved.