不同碱性材料对酸性重金属污染土壤的钝化效果及其作用机理简析

Effect and Mechanism of Different Kind Alkaline Type Heavy Metal Passivators

碱性材料是常用的土壤重金属钝化材料,不同碱性材料对重金属的钝化效果也不尽相同。本文通过应用实验,对比了各类氧化钙材料、碳酸钙类材料、碱性硫化物材料以及碱性多孔材料对酸性重金属铅(Pb)、镉(Cd)污染土壤的钝化效果特点,并对其作用机理做了分析。氧化钙类材料碱性适中,但钝化时效性不佳,氧化钙、氢氧化钙30 d的钝化效果较7 d(或15 d)均出现了一定程度的下降;碳酸钙类材料钝化效果较为稳定,但钝化率不高;硫化物中,3%的九水硫化钠30 d可将土壤中重金属铅(Pb)有效态稳定降低约58.6%,但会对土壤产生板结,pH值影响过大等负面影响,应用受到限制;多孔碱性材料碱性温和,钝化稳定性好,具有良好的应用前景。

Alkaline material is widely used as passivator in heavymetal polluted soil,but the passivating effect of different alkaline material is varying.Calcium oxide type materials,calcium carbonate type materials,alkaline sulfide materials and modified fly ash were used as passivator in lead and cadmium contaminated soil.The passivating effect and mechanism of these materials was investigated.Calcium oxide type materials have mild alkaline effect,but their passivating rate of 30d has decreased,compared to 7 d or 15 d period.Calcium carbonate type materials’effect is more stable,but their passivating effect is not as good as Calcium oxide materials.Sodium sulfide is most effective among these materials with an available Pb decreased rate of 56.8% in 30 d,but it also brought a most serious negative side effect to soils,which limited its application.Alkaline porous materials have a mild and stable alkalinity,obvious passivating effect,and very limited side effect to soil,which make it have a very good application prospect in soil heavymetal passivating field.