Dissolution of mimetite Pb5(AsO4)3Cl in low-molecular-weight organic acids and EDTA |
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Authors: | Bajda Tomasz |
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Institution: | AGH University of Science and Technology, Faculty of Geology, Geophysics and Environment Protection, Department of Mineralogy, Petrography and Geochemistry, al. Mickiewicza 30, 30-059 Krakow, Poland |
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Abstract: | Due to its relatively low solubility, mimetite Pb5(AsO4)3Cl may control Pb and As(V) solution levels at a low value in contaminated soils. The time-dependent dissolution of mimetite by low-molecular-weight organic acids (LMWOAs) such as acetic, lactic, citric, and ethylene diamine tetra-acetic acid (EDTA) was determined. At pH 3.5, the presence of citric acid or EDTA significantly increases the solubility of mimetite while acetic or lactic acids show little effect. The effect of all organic anions on the dissolution of mimetite increased with the increase in solution pH. The rate of mimetite dissolution depended on the kind and concentration of organic solvents in the sequence rEDTA > rlactate > racetate > rcitrate. Soluble Pb and As(V) released in LMWOAs and EDTA were higher than the WHO guideline value for these elements in drinking water (10 μg As(V) L−1, 10 μg Pb L−1). This suggests that soil organic acids in rhizosphere can potentially liberate Pb and As(V) from mimetite in contaminated soils. |
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Keywords: | Lead Arsenate Citrate Acetate Lactate Dissolution rate |
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