Effect of Soil Washing with Ferric Chloride on Cadmium Removal and Soil Structure
In China, arable soils contaminated with cadmium (Cd) threaten human health. Ferric chloride (FeCl<sub>3</sub>) is a highly efficient agent that can remove Cd from contaminated soils. However, it is unknown whether FeCl<sub>3</sub> damages the soil structure and consequently...
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| Autores principales: | , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/93e0ed7a20424eacb7f85ffa51239ece |
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| Sumario: | In China, arable soils contaminated with cadmium (Cd) threaten human health. Ferric chloride (FeCl<sub>3</sub>) is a highly efficient agent that can remove Cd from contaminated soils. However, it is unknown whether FeCl<sub>3</sub> damages the soil structure and consequently affects crop growth. In this study, we investigated the impacts of Cd extraction by FeCl<sub>3</sub> on the structure of a paddy soil on the basis of comparisons of control (without washing agents) and hydrochloric acid (HCl) treatments. According to our results, the removal efficiency increased with the decrease in soil initial pH, as adjusted by FeCl<sub>3</sub>. However, the low pH of 2.0 caused a partial loss of soil mineral components, with an Al release of 4.4% in the FeCl<sub>3</sub>-treated soil versus 1.3% in the HCl-treated soil. In contrast, the amount of released Al was less than 0.2% in the control and in the FeCl<sub>3</sub> treatments with initial pH values of 3.0 and 4.0. The washing agents caused soil TOC loss of 27.1%, 17.5%, and 2.76% in the pH 2.0, 3.0, and 4.0 FeCl<sub>3</sub> treatments, compared with 15.5% in the initial pH 2.0 HCl treatment. The use of FeCl<sub>3</sub> represents an optimum tradeoff between removal efficiency and the loss of soil components to restore Cd-polluted soils by adjusting the initial pH to 3.0 with the addition of FeCl<sub>3</sub>. Under this condition, the amount of Al loss was less than 0.2%, and the extraction efficiency reached 40.3%, compared to an efficiency of 39.7% with HCl at an initial pH of 2.0. In conclusion, FeCl<sub>3</sub> could effectively remove Cd from contaminated soil. |
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