超声波与EDTA联用对污染土中Pb的去除效果及其作用机理

以人工配置的Pb污染土为对象,进行了超声波与EDTA单独及联合作用对污染土中Pb的去除实验,利用改进BCR法测定了不同作用下土中Pb的4种形态。结果表明,超声波单独作用时对土中Pb的去除率很低,EDTA单独作用时去除率可以达到55%~90%。二者联合作用下,可以明显缩短EDTA单独去除反应的时间、节省EDTA用量并增强去除效果。超声波与EDTA联用增强Pb去除的机理,可以被认为是超声波促进了土中残渣态的Pb向弱酸提取态(F1)和可还原态(F2)转化,而EDTA能够去除的Pb形态主要是F1和F2。对于实验土中Pb的去除来说,EDTA清洗起主导作用,超声波起加速和加强作用。

Removal of Pb from contaminated soil with combined application of EDTA and ultrasound

The Pb removal efficiency after EDTA alone,ultrasound alone,combined ultrasound-EDTA treatment and distribution of Pb fractions using modified Community Bureau of Reference (BCR) method in treated soil were investigated.The results demonstrated that the removal efficiency of ultrasound treatment alone was very low,while EDTA treatment alone could achieve the removal efficiency of about 55%-90%.The combined treatment resulted in higher removal efficiency and faster removal rates.The mechanism could be considered that ultrasound promoted the fraction conversion from residual fractions into acid extractable fraction (F1) and reducible fraction (F2),EDTA could form stable complexes with heavy metals (mostly the F1 and F2),greatly improving their solubility and mobility.In this study,EDTA played the leading role while ultrasound accelerated the washing process and strengthened the removal efficiency.