有机酸对污染土壤重金属的淋洗效果研究

Removing Heavy Metals in Contaminated Soils by the Organic Acids

以湖南水口山某铅锌选矿厂附近受Zn、Pb、Cu、Cd严重污染土壤为对象,采用振荡淋洗技术,研究了有机酸在不同浓度、时间和液固比条件下对重金属的去除效果。实验结果表明,柠檬酸和酒石酸对重金属具有很好的去除效果,而草酸的去除能力很低;柠檬酸和酒石酸对Cd的去除效果最好,分别为61.5%和55.25%。随着时间的增加,有机酸对重金属的去除效率逐步提高,8h效果最好。柠檬酸和酒石酸对重金属的去除能力均依次为Cd>Zn>Pb>Cu,柠檬酸对重金属的去除率分别为59.5%、49.33%、43.48%、26.25%,酒石酸对重金属去除率分别为58.75%、46.4%、35.86%、34.4%。实验还发现固液比对重金属的淋洗效果影响很小。

Soil washing is considered as one of the most suitable and functional techniques for removing heavy metal. In this paper, contami- nated soils by the heavy metals of Pb, Zn, Cu, Cd were collected from the surroundings of a lead-zinc dressing plant in Shuikou Hill, Hunan Province. And the removal effects of the organic acid on heavy metal as a function of concentration, time and liquid-solid ratio by soil wash- ing were studied. The results showed that the citric acid and the tartaric acid had a sound effectiveness, whereas the removal rate of oxalic acid was very low. The Cd removal rate by the citric acid and the tartaric acid were the best, with the removal rate 61.5% and 55.25% respec- tively. The removal efficiency was gradually improved as a function of time. Best effect was obtained in 8 hours. The removal capacity order of the citric acid and the tartaric acid was：Cd〉Zn〉Pb〉Cu, for the citric acid, the removal rate was 59.5%, 49.33%, 43.48% and for the tartari- cacid, the removal rate was 58.75%, 46.4%, 35.86% and 34.4%, separately. Meanwhile, it was also found that solid-liquid ratio had little in- fluence on the removal rate of heavy metal.