Enhanced Electrokinetic Remediation of Heavy Metals in Glacial Till Soils Using Different Electrolyte Solutions
Publication: Journal of Environmental Engineering
Volume 130, Issue 4
Abstract
Previous electrokinetic remediation studies involving the geochemical characterization of heavy metals in high acid buffering soils, such as glacial till soil, revealed significant hexavalent chromium migration towards the anode. The migration of cationic contaminants, such as nickel and cadmium, towards the cathode was insignificant due to their precipitation under the high pH conditions that result when the soil has a high acid buffering capacity. Therefore the present laboratory study was undertaken to investigate the performance of different electrolyte (or purging) solutions, which were introduced to either dissolve the metal precipitates and/or form soluble metal complexes. Tests were conducted on a glacial till soil that was spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1,000, 500, and 250 mg/kg, respectively, under the application of a 1.0 VDC/cm voltage gradient. The electrolyte solutions tested were EDTA (ethylenediaminetetraacetic acid), acetic acid, citric acid, EDTA, and sulfuric sulfuric acid. The results showed that 46–82% of the Cr(VI) was removed from the soil, depending on the purging solution used. The highest removal of Ni(II) and Cd(II) was 48 and 26%, respectively, and this removal was achieved using acetic acid. Although cationic contaminant removal was low, the use of NaCl as an anode purging solution and EDTA as a cathode purging solution resulted in significant contaminant migration towards the soil regions adjacent to the electrodes. Compared to low buffering capacity soils, such as kaolin, the removal of heavy metals from the glacial till soil was low, and this was attributed to the more complex composition of glacial till. Overall, this study showed that the selection of the purging solutions for the enhanced removal of heavy metals from soils should be primarily based upon the contaminant characteristics and the soil composition.
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Information
Published In
Journal of Environmental Engineering
Volume 130 • Issue 4 • April 2004
Pages: 442 - 455
Copyright
Copyright © 2004 American Society of Civil Engineers.
History
Received: Jul 13, 2001
Accepted: Feb 9, 2003
Published online: Mar 15, 2004
Published in print: Apr 2004
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