Abstract
Electrokinetic soil remediation is an effective in-situ separation and removal technique used for extraction of heavy metals and some organic compounds from fine-grained soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils. It is clear that electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. Contaminants that are adsorbed on the soil or are present as precipitates can not be effectively removed. In particular, the solubility of most heavy metals may be significantly reduced at elevated pH values. When impurities such as iron oxides are present, electrokinetics alone may not be effective in the extraction of heavy metals due to the higher acid/base buffer capacity. Also, acidification of the medium might cause large weight losses by dissolution of part of the solid matrix. It would therefore be better if the treatment were performed at neutral pH.
In the present study, the effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is examined. The complexing agent selected was ethylenediaminetetraacetic acid (EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and is successfully removed at the anode reservoir.
