Thermally induced changes in solubility and speciation of lead and iron minerals in a contaminated soil
Journal
Soil Science Society of America Journal
Journal Volume
84
Journal Issue
6
Pages
1846-1853
Date Issued
2020
Author(s)
Abstract
This study investigated the effects of thermal treatment on the solubility and speciation of lead (Pb) adsorbed on synthesized hematite (Pb-Hm) and in an anthropogenically contaminated soil. The temperature of thermal treatment ranged from 100 to 900?°C, and the speciations of Pb and iron were determined using X-ray absorption fine structure spectroscopy. In Pb-Hm samples, the concentration of water-extractable Pb significantly decreased after being treated at 300 and 600?°C (?0.50?mg Pb L–1) compared with the untreated sample (9.83?mg Pb L–1). Under this temperature range, about 50% of the Pb-Hm was transformed into massicot (β-PbO). At 700?°C and above, a slight increase of water-extractable Pb was probably caused by the formation of minium (Pb3O4). In the contaminated soil, water-extractable Pb increased gradually from 0.30 to 0.40?mg Pb L–1 with increasing temperature from 25 to 200?°C; then it decreased rapidly to 0.09?mg Pb L–1 at 300?°C and further decreased to 0.004?mg Pb L–1 at 900?°C. Cerussite (PbCO3) and Pb associated with hematite were the major Pb species in the contaminated soil. In the process of thermal treatment, the significant decrease of water-extractable Pb in the contaminated soil was caused by the transformation of cerussite into hematite-associated Pb, accompanied by the transformation from ferrihydrite to hematite. ? 2020 The Authors. Soil Science Society of America Journal ? 2020 Soil Science Society of America
Subjects
Contamination; Heat treatment; Hematite; Iron metallography; Lead metallography; Lead oxide; Soil pollution; Soils; Solubility; X ray absorption; X ray absorption fine structure spectroscopy; Contaminated soils; Ferrihydrites; Increasing temperatures; Iron minerals; Temperature range; Thermally induced; Lead removal (water treatment); absorption; anthropogenic source; cerussite; concentration (composition); extraction method; ferrihydrite; hematite; iron; lead; sampling; soil pollution; speciation (chemistry)
Type
journal article