EDTA及其回收溶液治理重金属污染土壤的研究

试验结果表明,EDTA能够有效地萃取土壤重金属,由于其价格较贵和不易被降解等特点,限制了它的广泛运用.在运用MINTEQA2模型对萃取液中重金属离子形态分析的基础上,选用Na2S沉淀法将重金属从EDTA萃取液中有效分离.同时将回收的EDTA连续进行萃取土壤重金属,由于回收EDTA浓度下降的原因,其效果比新鲜EDTA的要稍微差一点,但从经济和效率上来说,仍旧可以用来治理重金属污染的土壤.

Removal of heavy metals from contaminated soils with fresh and recycled EDTA

Experiments showed that EDTA has most effectiveness in removing heavy metals from both contaminated soils; however, EDTA is relatively expensive and cannot be readily degraded by conventional biological treatment processes. Thus, EDTA may be recycled and reused. Species distributions of heavy metals in the extraction solutions were analyzed with MINTEQA2 computer programme at working condition, metal-EDTA was found to be predominant fractionation among metal species. Metals and EDTA were separated efficiently by Na₂S addition from the extraction solution. After that, the recycled EDTA was reused to remove heavy metals from contaminated soils. The extracting and recycling procedures were repeated four times. Although the recycled EDTA showed the leaching ability from both contaminated soils, the extraction efficiencies of heavy metals with the recycled EDTA were lower than those with the fresh EDTA because of the residual Na2S and lower concentration of recycled EDTA than before.