无患子皂苷与柠檬酸协同洗脱污染土壤中镉铅

以某废弃铅锌矿区重金属污染土壤为研究对象,采用无患子皂苷与柠檬酸（CA）协同洗脱污染土壤中的Cd和Pb。以无患子果皮投加量为20 g/L所得水浸提液和浓度为0.3 mol/L的CA配制复配淋洗剂。在浸提液中添加CA后,能有效提高对土壤中Pb的去除率。在浸提液和CA的体积比为1∶3、淋洗剂pH为5、淋洗时间为12.0 h的条件下,复配淋洗剂对Cd和Pb的去除率分别为75.2%和41.6%。双常数方程和Elovich方程均可较好描述复配淋洗剂对污染土壤中Cd和Pb的淋洗过程,表明Cd和Pb的解吸主要为非均相扩散过程。复合淋洗剂能有效降低土壤中Cd的可交换态和Pb的铁锰氧化态含量,并可促进重金属形态的转变。

Synergistic leaching of Cd and Pb from contaminated soil using Sapindus saponins and citric acid

Taking the heavy metals contaminated soil in an abandoned lead-zinc mining area as the research object,Cd and Pb in the contaminated soil were synergistically leached using Sapindus saponin and citric acid （CA）. A compound leaching agent was prepared with the water extract of 20 g/L soapberry peel and 0.3 mol/L CA. After adding CA to the extract,the removal rate of Pb in the soil was effectively improved. Under conditions of volume ratio of extract to CA 1∶3,leaching agent pH 5 and leaching time 12.0 h,the removal rate of Cd and Pb was 75.2% and 41.6%,respectively. Both the double constant equation and the Elovich equation can describe the leaching process of Cd and Pb in contaminated soil by the compound leaching agent,indicating that the desorption of Cd and Pb is mainly a heterogeneous diffusion process. The compound leaching agent can effectively reduce the content of exchangeable state of Cd and Fe-Mn oxidation state of Pb in the soil,and can promote the transformation of heavy-metal speciation.