Stabilization of lead in two artificial contaminated calcareous soils using stabilized nanoscale zero-valent iron particles with/without chelating agents

Nanoscale zero-valent iron particles (nZVIs) have been used as the stabilizing materials for remediation of heavy metals (HMs). The usage of nZVIs in the presence of oxygen is a challenging task. When this material comes in contact to air, immediately oxide formation takes place. Thus, preparation of air-stable nZVIs is necessary for successful remediation process. Therefore, the present study has attempted to evaluate the effects of three kinds of synthesized nZVIs, including nZVI_EDTA (stabilized by ethylenediaminetetraacetic acid), nZVI_DTPA (stabilized by diethylenetriamine pentacetic acid) and nZVI (without chelating agent), to determine their ability to stabilize lead (Pb) in two Pb-spiked soils. Pb-spiked soils were separately incubated with additives at the rates of 0.5% and 2% (W/W) for 90 days. The efficacy of nZVIs was evaluated by desorption kinetic and chemical fractionation experiments. According to the results, addition of nZVI_EDTA, nZVI_DTPA and nZVI significantly decreased Pb release by 70.1–86.4%, 56.5–70.6% and 24.3–49.2%, respectively. Among the three kinds of nZVIs, nZVI_EDTA was the most effective treatment in decreasing desorption and mobility factor of Pb. In practice, all three kinds of nZVIs are effective in Pb immobilization, while application of nZVI_EDTA at the rate of 2% was the best treatment to immobilize Pb in polluted soils.