柠檬酸复合淋洗剂对镉污染土壤淋洗效果研究

Study on Leaching Effect of Citric Acid Compound Leaching Agent on Cadmium-contaminated Soil

本文以镉污染土壤为材料,采用振荡淋洗方法研究了柠檬酸复合淋洗剂对镉的去除效果。结果表明:柠檬酸+硫代硫酸钠处理和柠檬酸+柠檬酸铵+硫代硫酸钠处理对土壤中镉的去除率均较高,第1次淋洗去除率在80%以上,第2次淋洗最大去除率仅为13.95%,第1次淋洗效果明显高于第2次;柠檬酸铵的加入可以缓解柠檬酸和硫代硫酸钠对土壤pH值、全氮和速效钾等理化性质的影响。从形态上分析,未淋洗土壤中的镉主要以可交换态和可还原态形式存在,2种形态占比达到93.82%。淋洗处理可将土壤中大部分的镉去除,去除率最大可达98.21%,而且淋洗后土壤中可氧化态和残渣态镉所占比例增加。

In this paper, the cadmium-contaminated soil was used as the material, and the removal effect of citric acid compound leaching agent on cadmium was studied by the method of oscillating leaching. The results showed that both citric acid +sodium thiosulfate and citric acid +ammonium citrate +sodium thiosulfate had high leaching rates for cadmium, and the first leaching rate was above 80%. The maximum leaching rate of the second leaching was only13.95%. The first leaching effect was significantly higher than that of the second leaching. The addition of ammonium citrate could alleviate the effects of citric acid and sodium thiosulfate on soil p H, total nitrogen, exchangeable potassium and other physicochemical properties. From the analysis of morphology, cadmium mainly existed in exchangeable form and reducible form in unwashed soil, and the two forms reached 93.82%. Leaching treatment could remove most of the cadmium in the soil, the maximum removal rate could reach 98.21%, and the proportion of oxidative form and residue form of cadmium in the soil after leaching increased.