采用不同提取剂对排土场土壤进行重金属提取

摘要

以铜矿受污染土壤为对象,研究柠檬酸(CA)、草酸(OA)、乙二胺四乙酸(EDTA)、氨三乙酸(NTA)四种提取剂对铜和锌的浸提效果.分析六种土壤样品中酸溶态、还原态、氧化态、残渣态形式存在铜和锌的占比.研究结果表明:当提取剂的溶度小于 0.02 mol/L时,相较于其他三种提取剂, EDTA 对于铜的提取效果最好,在相同提取剂浓度下,EDTA比其他提取剂的提取效率至少高15%.当提取剂的溶度小于 0.02 mol/L时,EDTA 对锌的提取效果最好.分别测定四种提取剂提取前、后铜的化学赋存形态,发现以酸溶态和还原态形式存在的铜被大量提取,含量显著减少.评估环境风险发现,提取之后环境风险显著下降.%The leaching behaviour of Cu and Zn from contaminated soils at a copper mine was investigated using four extractants: citric acid (CA), oxalic acid (OA), ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA). Six soil samples were characterized for the distribution of four chemical fractions of Cu or Zn (acid-soluble, reducible, oxidizable and residual). For the extraction of Cu, EDTA is more effective than other extractants when the concentration is less than 0.02 mol/L. The leaching efficiency for Cu was at least 15% higher for EDTA than for the other extractants at the same concentrations. Similar leaching behaviour was observed in the extraction of Zn. After extraction by CA, OA, EDTA or NTA, the acid-soluble fractions and the reducible fractions of Cu were the main fractions extracted. The potential environmental risks related to speciation were evaluated, and after extraction these risks were reduced.