Influence of EDTA and NTA on heavy metal extraction from sandy loam contaminated soils
Abstract In this study, Pb, Cd, and Zn as heavy metal compounds were extracted from the sandy loam soil; the soil was prepared synthetically inside the laboratory and also taken from the field by using EDTA and NTA as the chelating agents. By using EDTA 0.1 M to extract the contaminants from the synthetically contaminated soil with single metal concentration of 500 mg/kg, the efficiency of extracting Pb, Cd, and Zn in the first pore volume (PV) were found to be respectively 43.84% 20.6% and 43.7% the corresponding amounts after the third PV for the contaminants were 85.25% 83.2% and 69.7% respectively. The efficiency of NTA 0.1 M in extracting Pb, Cd, and Zn in the first PV was 8.3% 59.6% and 14.87% respectively; after the third PV, the corresponding efficiency reached to 21.8% 83.56% and 24.49% respectively, for the contaminants. At pH 4.5, the efficiency of extracting Pb, and Zn using EDTA and NTA were higher than other levels of pH; and also, the maximum Cd extraction was achieved in pH 7. Considering the samples taken from the field, the extraction efficiency of Pb, Cd, and Zn using EDTA 0.1 M after the fifth PV were 89.42% 64.21% and 63.5% respectively.