天然有机酸与2-羟基-β-环糊精复合对土壤Pb淋洗修复研究

Study on Remediation of Pb Leaching in Soil by Combination of Natural Organic Acid and 2-hydroxy-β-cyclodextrin

以某废弃的化工遗留场地Pb污染土壤为研究对象,选取酒石酸、柠檬酸、2-羟基-β-环糊精作为淋洗剂。采用批量振荡淋洗法研究不同条件下的单一淋洗剂和复合淋洗剂对污染土壤Pb的去除效果,并采用动力学方程对淋洗过程进行拟合。振荡实验结果表明:单独淋洗时,酒石酸浓度在60mmol/L时去除率最大,达到58%;柠檬酸浓度在60mmol/L时去除率达到53%;复合淋洗时,酒石酸与2-羟基-β-环糊精在体积比2:1,固液比为20:1,振荡时间为10h时去除率最大,最大为58%,高于同等条件下单独使用酒石酸的10%。柠檬酸与2-羟基-环糊精在体积比3:1,固液比为30:1,振荡时间为8h时去除率最大,最大为53%,高于同等条件下单独使用柠檬酸7%;动力学研究表明,有机酸复合淋洗更符合一级淋洗方程。

The Pb contaminated soil of a abandoned chemical site was taken as the research object,tartric acid,citric acid and 2-hydroxy-βcyclodextrin were selected as leaching agents.Batch oscillatory leaching method was used to study the removal effects of single leaching agent and compound leaching agent on Pb from contaminated soil under different conditions,and kinetic equation was used to fit the adsorption degradation.The results of oscillation experiment showed that the removal rate reached 58%when the concentration of tartric acid was 60 mmol/L.When citric acid was 60 mmol/L,the removal rate reached 53%.When combined leaching,the volume ratio of tartric acid to cyclodextrin was 2:1,the solid-liquid ratio was 20:1,the oscillation time was 10 h,and the pH was 3,the maximum removal rate was 58%,which was higher than 10%of tartric acid alone under the same conditions.When the volume ratio of citric acid and 2-hydroxy-cyclodextrin was 3:1,the solid-liquid ratio was 30:1,the shaking time was 8 h,and pH was 3,the maximum removal rate was 53%,which was 7%higher than that of citric acid alone under the sa me conditions.Kinetic studies show that the organic acid complex leaching equation is more complex than the first order leaching equation.