钢铁工业遗留场地土壤重金属洗脱剂筛选研究

土壤重金属污染限制了工业遗留场地再利用,通过振荡试验考察了HCl、HNO3和EDTA对工业遗留场地土壤中超标重金属Pb、Zn、Cd和As的洗脱效果。结果表明：土壤Pb、Zn、Cd、As的脱除效果均随洗脱剂浓度增加而增加;HCl、HNO3和EDTA等3种洗脱剂浓度分别为0.5、0.5和0.1 mol.L-1时,土壤Pb、Cd质量分数可降低至场地安全再利用的控制标准以内（分别为140 mg.kg-1、1mg.kg-1）;洗脱剂浓度分别增至2、2和0.2 mol.L-1时,土壤Pb、Cd质量分数继续降低,Zn、As质量分数有大幅降低但没有达到其相应的场地安全控制标准（分别为200、20 mg.kg-1）;与EDTA相比,HCl在低浓度时的重金属脱除效果较差,但HCl浓度增加对重金属脱除率的提高效果更为明显;洗脱液pH值（7.88~0.15）与重金属脱除率均呈显著负相关且与As的负相关系数最小,说明洗脱液pH值变化对As去除的影响相对较小;与HCl和HNO3相比,EDTA洗脱液pH值与Pb脱除率之间的负相关系数较大,与Zn、Cd、As脱除率之间的负相关系数较较小,说明EDTA洗脱液pH值变化更易对Pb的去除产生影响。

The selection of eluting agents in remediation of the heavy metal polluted soil left by a steel plant

Soil heavy metal contamination limited reutilization of brownfield site,and a series concentration of HCl,HNO3,and EDTA were prepared in our laboratory batch test to examine the removal effect of Pb,Zn,Cd,and As,all of which have exceeded seriously the brownfield site reuse standards in china.The results indicated that： Higher concentration of Eluting agents produced greater metal removal efficiency;soil Pb and Cd concentration could reach the site reuse standard（140,1 mg·kg-1）（HJ 350-2007） when the concentration of HCl,HNO3,and EDTA increased to 0.5 mol·L-1,0.5 mol·L-1,and 0.1 mol·L-1 respectively;Pb,Cd,Zn,and As concentration continue to decrease when the corresponding concentration increased further to 2 mol·L-1,2mol·L-1,and 0.2 mol·L-1 respectively and Zn concentration could approach the standard while As failed（200 mg·kg-1,20 mg·kg-1）;HCl has poor effect on metal removal efficiency in low concentration when compared with EDTA,but its removal ability could greatly improved as the concentration increase;Eluting solution pH value（7.88-0.15） was significantly negatively correlated to heavy metal removal efficiency,and the negative correlation coefficient for As was the smallest among the four heavy metals,which explained less effect of solution pH value on As removal;the negative correlation coefficient between EDTA solution pH value and Pb removal efficiency was comparatively greater among three types of Eluting solutions when compared with HCl and HNO3,which explained greater effect of EDTA solution pH value on Pb removal.