In this study, the feasibility of ferric as an oxidizing and extracting agent for remediation of Pb-contaminated soil was investigated to enhance extraction of Pb with various mineral forms such as massicot (PbO), cerussite (PbCO3), galena (PbS), anglesite (PbSO4), and pyromorphite (Pb5(PO4)3OH). The dissolution of these minerals is dependent on their solubility, i.e., stability constants, and, log Ksp of PbO, PbCO3, PbS, PbSO4, and Pb5(PO4)3OH is 12.89, 4.65, -7.79, -27.51, and -4.14, respectively. Among them, oxidation process is necessary to dissolve PbS because of a much lower solubility than others. Ferric generates hydrogen ions (H+) via dissociation of water molecule, which can enhance dissolution of Pb minerals with high solubility. In addition, sulfide mineral such as PbS can be extracted oxidatively by ferric because of a high redox potential of 0.77 V. Experimental results showed that ferric could effectively dissolve Pb minerals. However, ferric chloride (FeCl3) might precipitate cotunnite (PbCl2), a form of Pb mineral because chloride ions (Cl-) were combined with Pb extracted into solution. Therefore, ferric nitrate (Fe(NO3)3) could enhance more removal of Pb minerals than FeCl3 because nitrate is a relatively inert anion for complexation for metals.

Extraction characteristics of Pb using ferric-mineralogical approach

251st National Meeting (2016)

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