Chelate Agents Enhanced Electrokinetic Remediation for Removal Cadmium and Zinc by Conditioning Catholyte pH

Abstract

The feasibility of using chelate agents to enhance the electrokinetic remediation of heavy metal contaminated soils has been investigated in this study. Chelate agents were used as washing solutions as well as purging solutions at the electrode compartments. The pH value of the soil significantly affects the removal of heavy metal ions. Due to electrolysis reaction pH increases near the cathode. Without conditioning of the pH value metals precipitate as hydroxides. This problem is solved by the addition of an acid in the cathode compartment. The heavy metals that are dissolved will move to either the cathode or the anode, depending on their charges. This paper presents the results of electrokinetic extraction of cadmium using acetic acid, citric acid and pyridine-2,6-dicarboxylic acid (PDA) as washing and purging solutions, and the removal of zinc using ethylenediamine tetraacetic acid (EDTA) and sodium metabisulfite (Na2S2O5) as washing and purging solutions, respectively. The results showed that the increased experimental time induced a higher removal efficiency of cadmium and zinc.