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Membrane Water Treatment Volume 9, Number 3, May 2018 , pages 137-146 DOI: https://doi.org/10.12989/mwt.2018.9.3.137 |
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Remediation of heavy metal-contaminated soils using eco-friendly nano-scale chelators |
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Heejun Lim, Sungyoon Park, Jun Won Yang, Wooyoun Cho, Yejee Lim, Young Goo Park, Dohyeong Kwon and Han S. Kim
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| Abstract | ||
| Soil washing is one of the most frequently used remediation technologies for heavy metal-contaminated soils. Inorganic and organic acids and chelating agents that can enhance the removal of heavy metals from contaminated soils have been employed as soil washing agents. However, the toxicity, low removal efficiency and high cost of these chemicals limit their use. Given that humic substance (HS) can effectively chelate heavy metals, the development of an eco-friendly, performance-efficient and cost-effective soil washing agent using a nano-scale chelator composed of HS was examined in this study. Copper (Cu) and lead (Pb) were selected as target heavy metals. In soil washing experiments, HS concentration, pH, soil:washing solution ratio and extraction time were evaluated with regard to washing efficiency and the chelation effect. The highest removal rates by soil washing (69% for Cu and 56% for Pb) were achieved at an HS concentration of 1,000 mg/L and soil:washing solution ratio of 1:25. Washing with HS was found to be effective when the pH value was higher than 8, which can be attributed to the increased chelation effect between HS and heavy metals at the high pH range. In contrast, the washing efficiency decreased markedly in the low pH range due to HS precipitation. The chelation capacities for Cu and Pb in the aqueous phase were determined to be 0.547mmol-Cu/g-HS and 0.192mmol-Pb/g-HS, respectively. | ||
| Key Words | ||
| heavy metal; contaminated soil; soil washing; humic substance; chelating agent | ||
| Address | ||
| Heejun Lim, Sungyoon Park, Jun Won Yang, Wooyoun Cho, Yejee Lim, Han S. Kim: Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, Korea Heejun Lim, Young Goo Park, Dohyeong Kwon: Sehwa E&F, 196-17 3Gongdan3ro, Gumi, Gyungbuk, Korea | ||