淋洗法修复化工厂遗留地重金属污染土壤的可行性

Feasibility of washing as a remediation technology for the heavy metals-polluted soils left by chemical plant

通过室内模拟试验,采用振荡淋洗的方法研究了蒸馏水、HCl、H3PO4、草酸、CaCl2等淋洗剂对化工厂遗留地污染土壤中重金属的淋洗效果,探讨了淋洗剂浓度、淋洗时间、淋洗次数等对淋洗效果的影响,并研究了HCl处理前后土壤中重金属形态的变化.结果表明:蒸馏水、H3PO4、CaCl2等对Cr、Pb、Zn、Cu、Cd的去除率较低,大多数条件下重金属去除率均在1%以下,最大去除率仅为3.58%.2mol·L-1HCl在土水比为1∶3、反应时间为1h、2次淋洗的条件下可以达到最佳淋洗效果,Cr、Pb、Zn、Cu、Cd的去除率分别达到80.75%、88.69%、98.00%、79.33%和95.52%.形态分析结果表明,HCl能有效去除土壤中各种结合形态的重金属.

Laboratory simulation tests were conducted to examine the effects of different washing reagents （distilled water,HCl,H3PO4,oxalic acid,and CaCl2） in extracting the heavy metals from contaminated soils left by a chemical plant. The effects of reagent concentration,reaction time,and washing time on the washing efficiency were investigated,and the form variation of test heavy metals was determined before and after HCl washing. Distilled water,H3PO4,and CaCl2 could remove less than 1% of most heavy metals,and the highest removal rate was only 3.58%; while 2 mol HCl·L-1 could obtain the highest washing efficiency under the optimal conditions,i.e.,soil：liquid ratio was 1：3,reaction time was 1 hour,and the soils were washed twice by HCl solution. The removal rates of Cr,Pb,Zn,Cu,and Cd from test soils were 80.75%,88.69%,98.00%,79.33%,and 95.52%,respectively. Among the washing reagents,HCl could effectively remove all forms of heavy metals.