EDTA溶液萃取污染土壤中的重金属及其回收技术

 研究了EDTA萃取液中重金属的分离技术并将其应用于修复土壤污染.结果表明,EDTA溶液能有效地萃取土壤中重金属; Na₂S能沉淀分离EDTA溶液中的Cd, Cu, Pb,效率达99%以上,但沉淀Zn需要加入Ca(OH)₂,引入反应体系的Ca²⁺并不影响重金属的萃取和EDTA的回收;连续抽提能增加污染土壤中重金属的去除率,回收的EDTA连续使用10次,损失约30%.土壤中Cd和Pb的累积去除率分别达75.6%,72.5%.得到的硫化物沉淀含有很高的重金属,能很方便地处理或回收.

Extraction of heavy metals in contaminated soils with EDTA solution and their recovery technique

The technique of separating heavy metals in ethylenediamine-tetraacetic acid (EDTA) solution was studied and used for remediation of soils pollution. EDTA solution could extract effectively the heavy metals in soil. Na2S could separate sedimentarily Cd, Cu, Pb in EDTA solution with efficiency over 99%; but Zn precipitation required the addition of Ca(OH)2. Ca2+ introduced into the reaction system had no influence on extraction of heavy metals and EDTA recovery. Successive extractions process enhanced the removal rate of heavy metals in contaminated soils. The removal rates of Cd and Pb accumulation in soil reached 75.6% and 72.5% respectively. Successive use of recovered EDTA for ten times, EDTA losses were about 30%. The sulfide precipitates obtained had high concentrations of heavy metals and could be treated or recovered conveniently.