采用草酸和EDTA去除农田土壤中砷和镉污染

TREATMENT OF ARSENIC AND CADMIUM IN CONTAMINATED FARMLAND SOIL WITH OXALIC ACID AND EDTA

以湖南、广西某As和Cd污染土壤为研究对象,以草酸和EDTA为淋洗剂,研究其在污染土壤样品中的淋洗情况,探讨淋洗剂浓度、淋洗温度对淋洗效果的影响。结果表明:淋洗剂为0. 3 mol/L的草酸对As淋洗率最好,洗脱率达到90%; 0. 02 mol/L EDTA对Cd淋洗率最好,洗脱率达到70%;采用正交实验探讨了草酸和EDTA联合对土壤样品淋洗效果的影响,草酸和EDTA组合淋洗As和Cd的洗脱率分别为80%和50%。草酸和EDTA单一淋洗效果优于组合淋洗,草酸和EDTA在土壤重金属淋洗过程中存在拮抗作用。

The soil contaminated by heavy metals such as Cd and As in Hunan and Guangxi Province in China was used as a research object;oxalic acid and EDTA respectively served as eluents for the oscillatory leaching of contaminated soil samples.The influence of concentration of the eluents and leaching temperature on leaching effect was discussed.The results showed that the elution rate of oxalic acid with the concentration of 0.3 mol/L as the eluent was the best for As, reaching 90% and the elution rate of EDTA with the concentration of 0.02 mol/L was the best for Cd, up to 70%.The influence ofoxalic acid combined with EDTA on the leaching effect of soil samples was studied by an orthogonal test.The elution rates of oxalic acid combined with EDTA for As and Cd were respectively 80% and 50%.The single leaching effect of oxalic acid and EDTA was superior to the combined leaching.Oxalic acid and EDTA showed antagonism in the leaching process of heavy metals in the soil.