Removal of cadmium and lead from soil using aescin as a biosurfactant |
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Authors: | Kyung-Jin Hong Young-Kook Choi Shuzo Tokunaga Yutaka Ishigami Toshio Kajiuchi |
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Affiliation: | (1) Department of Environmental Chemistry and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 226 Yokohama, Japan;(2) National Institute of Materials and Chemical Research, 1-1, Higashi, 305 Tsukuba, Ibaraki, Japan |
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Abstract: | Remediation of a soil contaminated with cadmium or lead was performed by a soil washing process using aescin as a biosurfactant.
The removal of cadmium and lead from the soil was evaluated as a function of aescin concentration and pH in a batch process.
A 30-mM aescin solution was most effective in the removal of cadmium and lead at pH 6.8. Cadmium and lead migrated from the
soil to the aescin-containing aqueous phase, depending on the pH value. We found that 41% of cadmium (pH 7.8) and 25% of lead
(pH 2.8) in the soil matrix migrated into a 30-mM aescin solution. Also, the complexation of aescin with cadmium and lead
ions was confirmed by Fourier transform infrared spectroscopy and electrical conductivity measurements. As a result, the maximal
complexation capacity of aescin with metal ions was approximately aescin/cadmium=2∶1 and aescin/lead=3∶1 on a molar basis.
It was suggested that aescin may sequester cadmium and lead ions by the carboxylic and saccharide moieties. Then, the complex
of aescin with cadmium or lead may migrate to the aqueous phase as the result of dispersion. |
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Keywords: | Aescin biosurfactant cadmium lead soil washing |
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