柠檬酸对重金属复合污染土壤的淋洗修复效果与机理

Remediation of Soil Co-contaminated with Heavy Metals by Washing with Citric Acid:Batch Experiment and Extraction Mechanism

土壤淋洗修复是永久性的污染土壤修复方法之一.以Cd、Cu、Pb复合污染土壤为研究对象,采用振荡淋洗法结合形态分析技术研究了柠檬酸对重金属复合污染土壤的淋洗修复效果及其去除机理.结果表明,柠檬酸对复合污染土壤中的Cd和Cu具有较好的洗脱效果,而Pb的淋洗去除率相对较低.80mmol.L-1的柠檬酸对Cd、Cu、Pb的去除率分别能够达到90.4%、82.5%和38.6%.柠檬酸淋洗去除的重金属在土壤中主要以可交换态、碳酸盐结合态和铁锰氧化物结合态的形式存在.

Soil washing is one of the few permanent treatment alternatives to remove contaminants from soils. Batch experiment was conducted to evaluate the performance of potential capability of citric acid to washing co-contaminated soil with Cd,Cu and Pb. The fraction and distribution of heavy metals in soil were evaluated using the sequential extraction technique to discuss the mechanism of citric acid extraction. Results show that citric acid could effectively remove Cd and Cu from co- contaminated soil, but relatively low removal rate of Pb. The removal of Cd, Cu, and Pb is respectively 90.4%, 82.5%, and 38.6% washing with 80 mmol ·L-1 citric acid solution. The removed heavy metals by citric acid are mainly from the exchangeable, carbonate bound and Fe-Mn oxide fractions.