Role of Fe in Extractive Decontamination of Pb-Polluted Soils

Abstract

ABSTRACT The role of Fe in Pb solubilization by ethylenediamirtetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) from a highly contaminated (21% Pb by weight) battery reclamation site soil was investigated using batch extraction and sequential fractionation experiments. Based on relative complexing ability, soluble Fe(III) should inhibit Pb recovery using chelating agents, particularly under acidic conditions. Despite a large pool of available Fe (6.7% of soil by weight) and a marked increase in soluble Fe(III) with decreasing pH, Pb solubilization was nearly pH invariant. Since only 12% of FeT compared to 86% of PbT was solubilized by 4 × 10−2 M EDTA at pH 6, Pb and Fe apparently exist in differentially reactive forms within the soil. A nine-step chemical fractionation procedure confirmed that 80% of the soil Pb was present in non-detrital (soluble, weakly sorbed) forms in contrast to 94% of Fe existing in detrital (oxide occluded, residual) fractions. The kinetically slow dissolution of indigenou...