复合重金属污染高岭土的电动修复

摘要

根据电子废弃物拆解场地的污染特征,以复合重金属(Cu,Cd,Pb)污染高岭土为研究对象,考察了电动技术对污染土壤的修复效果.实验结果表明:在电压梯度为1 V/cm、阳极液为自来水、阴极液为柠檬酸-柠檬酸钠缓冲液(pH=5)、靠近阴极设置活性炭渗透反应墙(PRB)的条件下电动修复96 h后,Cu,Cd,Pb的平均去除率分别可达79.93％,99.43％,39.36％;土壤的酸碱性对电动修复效果影响显著,通过在阴极添加缓冲液维持土壤偏酸性条件,有利于重金属污染物的电动去除;在靠近阴极设置活性炭PRB可富集重金属,减少阴极液的污染;迁移率大的酸可提取态重金属较易去除,残渣态重金属稳定性强,去除率较低.%According to pollution characteristics of e-waste dismantling sites,kaolin contaminated with heavy metals (Cu,Cd,Pb) was selected as the research object,and the remediation effect by electrokinetics method was investigaeted.The experimental results showed that:Under the conditions of voltage gradiant 1 V/cm,using tap water as the anolyte and the citric acid-sodium citrate buffer solution (pH=5) as the catholyte,installing the activated carbon permeable reactive barrier (PRB) near the cathode and electrokinetic remediation time 96 h,the average removal rate ofCu,Cd,Pb was 79.93％,99.43％,39.36％,respectively;The pH of kaolin had significant impact on electrokinetic remediation,the electrokinetic removal of heavy metals was benefited from keeping a slightly acidic kaolin condition through the addition of buffering solution;The pollution of the catholyte could be reduced by enriching heavy metals on the activated carbon PRB near the cathode;The removal of acid-extractable-form heavy metals with high mobility was relatively easy,while the removal rate of residual-form heavy metals with high stability was low.