EDTAを利用した動電学的手法によるカドミウム汚染土壌の浄化に与えるpHの影響

概要

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In electrokinetic soil remediation, contaminants are removed from soil and groundwater by action of an electrical potential applied across electrodes embedded in the contaminated medium. Soluble substances can be removed effectively by electroosmosis and ionic migration. However, 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 oxide and carbonate minerals 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 ethylenediaminetetraacetic acid (EDTA) as complexing agent to enhance the removal of cadmium from kaolinite by ion migration is examined. The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As results of the study, cadmium migrated toward the anode without accumulation of cadmium and it was found that the effectiveness of EDTA for removing cadmium was significantly affected by the soil pH.
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