复合淋洗剂对高砷污染土壤修复效果及机理研究

Study on the Repairing Effect and Mechanism of Compound Eluent on High Arsenic Contaminated Soil

本文以湖北某砒霜厂高砷(As)污染土壤为研究对象,在前期研究基础上,通过振荡淋洗实验,将4种常用淋洗剂进行组合复合淋洗,讨论了最佳复合淋洗组合,并对复合淋洗前后砷形态的变化以及淋洗过程中土壤常量元素的释放规律进行探究。结果表明0.4 mol/L KH_(2)PO_(4)+0.1 mol/L EDTA复合淋洗剂淋洗效率最高,达到66.99%,相较单一淋洗剂淋洗效果提高了31.23%;3组复合淋洗剂对各形态As均有一定的去除效果,淋洗后土壤中的As主要以残渣态的形式存在;KH_(2)PO_(4)+EDTA复合淋洗剂淋洗As的解吸与Al、Fe、Ca这些常量元素的释放规律有着密切联系,土壤中难以去除的残渣态As,包裹在硅酸盐矿物晶格内部,从而导致土壤中As解吸过程受限。

In this paper,high arsenic(As)contaminated soil in a Hubei arsenic factory was taken as the research object.On the basis of previous studies,four commonly used leaching agents were combined and combined through oscillatory leaching experiment,the optimal combination of combined leaching was discussed,and the change of arsenic form before and after combined leaching and the release law of soil major elements during the leaching process were explored.The results showed that the leaching efficiency of 0.4mol/L KH_(2)PO_(4)+0.1 mol/L EDTA was the highest,reaching 66.99%,which was 31.23%higher than that of single leaching agent.All the three groups of compound leaching agents have a certain removal effect on the form of As,and the As in the soil after leaching mainly exists in the form of residue.The desorption of As eluted by KH_(2)PO_(4)+EDTA complex eluent is closely related to the release law of major elements such As Al,Fe and Ca.Residual As,which is difficult to remove in soil,may be wrapped in the crystal lattice of silicate minerals,thus limiting the desorption process of As in soil.