TX-100与EDTA联用对Pb、Cd复合污染土壤修复研究

摘要

乙二胺四乙酸二钠(EDTA)是土壤重金属污染修复常用的洗涤剂,单一的 EDTA 无法全面去除实际污染土壤中的重金属.本文以典型生活垃圾肥污灌土壤为研究对象,采用批试验方法,研究了曲拉通(TX-100)与EDTA复配对污灌土壤中重金属Pb、Cd的洗涤修复效果和最优条件下洗涤前后重金属形态变化.结果表明:10 mmol/L的TX-100与浓度大于4 mmol/L的EDTA表现协同作用,并在摩尔比为10︰8时重金属去除效率趋近平衡;当复配试剂在pH为4、振荡强度为150 r/min和振荡时间为8h时,Pb、Cd去除率分别到达了46.4 %和49.4 %.经复配试剂洗涤,Pb铁锰结合态去除量最大,其去除率为58.1%,Cd可交换态和碳酸盐结合态去除率最大分别为65.85 %和68.18 %;洗涤后Pb残渣态比例增加到56.3 %,Cd可交换态和碳酸盐结合态的百分比显著降低.%Ethylenediamine tetraacetic acid (EDTA) has been commonly used in remediation of heavy metal contaminated soil, however, EDTA could not completely remove the actual contaminated soil alone. Triton X-100(TX-100) and EDTA were selected as eluents. Leaching experiments were conducted to evaluate the removal of lead and cadmium from the contaminated soil. As well as morphological distribution of heavy metals before and after the leaching progress. Pb and Cd showed synergistic effect when treated by the combination of 10 mmol/L of TX-100 and 4 mmol/L of EDTA, and the heavy metal removal system reached balance at a molar ratio of 10: 8. The optimum Pb,Cd removal rate were 46.4% and 49.4%,respectively, at the condition of pH at 4, oscillation intensity at 150 r/min and the vibration time was 8h. Leaching by the compound reagent catharsis, the Fe-Mn oxide bound Pb, the exchangeable Cd and carbonate Cd showed the removal rate of 58.1%, 65.85% and 68.18%, respectively. The residual Pb ratio increased to 56.3% after leaching, while exchangeable and carbonates Cd reduced significantly.