以牺牲阳极强化的电化学联用方法修复铬污染土壤

ELECTROCHEMICAL COMBINED REMEDIATION OF CHROMIUM CONTAMINATED SOIL BASED ON STRENGTHENING BY ANODE CONSUMPTION

为解决重金属污染土在电动法修复过程中存在的聚焦效应问题,提出了牺牲铁阳极的电化学联用修复技术。在传统电动修复方法基础上增加电解液净化循环装置,优化Cr(Ⅵ)还原及沉淀所需技术参数,并与传统电动修复技术进行对比,探讨其修复效果及适用性。结果表明:迁出的Cr(Ⅵ)可在Fe^2+作用下被还原为Cr(Ⅲ)并沉淀,pH、电压梯度、电流密度、电极面积均会影响其反应速率,电极距离对反应速率无直接影响,主要影响电解功率。Cr(Ⅵ)还原-沉淀反应的最佳技术参数为:pH值5~6.5,电压梯度0.8 V/cm,电流密度>6.67 mA/cm^2,电极面积90 cm^2,电极距离15 cm;较传统电动修复技术,以牺牲阳极强化铬污染土的电化学联用修复技术中,土壤室不同点位的去除率波动范围在10%,最高点位的去除率提高近24%,达93.4%。靠近阳极附近土体中Cr(Ⅵ)去除率从0.24%提高到80.38%。以牺牲阳极强化污染土的电化学联用修复方法不仅有效解决了重金属迁移的聚焦问题,而且有助于促进土中重金属污染物的整体性迁出。

In order to solve the problem of focusing effect in the process of electrokinetic remediation of heavy mental contaminated soil,the electrochemical combined remediation technology at the expense of iron anode was proposed.Based on the traditional electric repair method,the combined remediation technology added the electrolyte purification circulation device and it optimized the technical parameters for the reduction and precipitation of Cr(Ⅵ).The remediation effect and applicability were evaluated by comparing with the traditional electric remediation technology.The results showed that:1)The removed Cr(Ⅵ)can be reduced to Cr(Ⅲ)and precipitated under the action of Fe^2+,and the parameters of pH,voltage gradient,current density and electrode area all affected the reaction rate.Electrode distance had no direct impact on the reaction but reflected in the power of electrolysis.2)The best technical parameters of Cr(Ⅵ)reduction-precipitation reaction were:pH value was 5~6.5,voltage gradient was 0.8 V/cm,current density was more than 6.67 mA/cm^2,electrode area was 90 cm^2,and electrode distance was 15 cm.3)Compared with traditional electric remediation technology,the removal rate of different soil points fluctuated in the range of 10%,and the removal rate of highest point was increased by nearly 24%(nearly 93.4%)in the electrochemical combined remediation technology.Especially,the removal rate of chromium near anode increased from 0.24%to 80.38%.4)The electrochemical combined remediation method based on strengthening by anode consumption could not only solve effectively the focus problem,but also help to promote the overall migration of heavy metal in contaminated soil.