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| Combined Leaching of Heavy Metals in Soil by Citric Acid and Saponin |
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| KeyWord:heavy metals; contaminated soil; citric acid; saponin; combined effect; leaching |
| Author Name | Affiliation | | XU Zhong-jian | Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China | | XU Dan-dan | Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China | | GUO Su-hua | Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China | | QIU Xi-yang | Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China | | LI Fang-wen | Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China |
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| Abstract: |
| Soil contamination with heavy metals has become an increasingly severe global environmental issue. Considerable efforts have been made to remediate contaminated soils. In this study, Zn, Pb and Cu spiked soil was employed to evaluate leaching of metals from the soil with citric acid and saponin. First, optimal concentration of citric acid or saponin was determined in mono-leaching experiments with single citric acid or saponin. Second, removal rates of heavy metals were examined by co-leaching of citric acid and saponin at their optimal concentrations. Finally, chemical species of heavy metals in soils after co-leaching were analyzed using BCR procedure. The optimal concentration of citric acid was 40 mmol·L-1 and saponin 3%. The removal rates of Zn and Pb were greatest at 1∶5 volume ratio of citric acid to saponin solution, being 67.2% and 68.8%, respectively. However, the greatest removal rate of Cu was 37.7%, at 1∶1 volume ratio of citric acid to saponin, less than that of citric acid alone. Compared to the control, combined leaching removed 96% of acid soluble, 38.9% of oxidizable and 51.5% of residual Zn, but increased reducible Zn significantly. Leaching reduced both acid soluble and reducible Pb and Cu by 80%. Oxidizable and residue Cu did not change significantly after leaching. |
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