Electroremediation of Lead-Contaminated Kaolinite using Cation Selective Membrane and Different Electrolyte Solutions
2013
Naidu, R. | Sreedaran, B. R. | Smith, Euan
Electrokinetic extraction, which is an emerging technology, can be used for in situ removal of contaminants by the application of a direct current (DC) electric field across the contaminated subsurface soil. In this study, a kaolinite spiked with Pb (720 mg kg-1) was used to investigate the removal of Pb through electrokinetic extraction in the presence or absence of a cation selective membrane (CSM). The contaminated kaolinite was subjected to a constant DC voltage (2 V cm-1) for 4 days. A low DC voltage applied in absence of CSM developed a high pH interface within the electrokinetic cell. The mobility of Pb thus decreased due to the remarkable rise in the pH values. The inclusion of a CSM improved the removal efficiency but could not achieve the critical surface pH (<pH 3.5). The removal efficiency increased in the presence of Ca(NO3)2, such that 95 % of the spiked Pb was extracted from kaolinite, with 88 % of the Pb being recovered from the cathode chambers. In contrast, only 24 % of the spiked Pb was removed in the presence of ethylenediaminetetraacetic acid (EDTA). Moreover, Pb was detected in the anode chamber solution and 60 % of the spiked Pb accumulated at the anode. In the presence of both EDTA and Ca(NO3)2, Pb migrated and accumulated at the anode, thus indicating that Ca has a negligible effect in the presence of EDTA. © 2013 Springer Science+Business Media Dordrecht.
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