Enhanced electromigration and electro-osmosis for the remediation of an agricultural soil contaminated with multiple heavy metals

The remediation of agricultural soil contaminated with Cd, Co, Cr, Cu, Pb, and Zn was carried out by enhanced electrokinetic remediation using sulfuric acid or organic acids (EDTA, Citric acid and Acetic acid) as the processing fluid. The unenhanced electrokinetic treatment with DI water in the anolyte and catholyte resulted in some mobilization of the heavy metals, but only minor removal was observed. The use of EDTA and acetic acid in the catholyte favored the mobilization of the metals and the formation of chelates and complex ions. Citric acid was very effective in the solubilization and removal of heavy metals because of: (a) the acidification of the soil specimen and subsequent mobilization of metals, and (b) the enhanced electro-osmotic flow that favored the transportation of mobilized cations towards the cathode. The removal of Cd, Co, Cu and Zn was over 70%, whereas Cr and Pb showed very limited removal (below 12%) because of their strong immobilization in the soil.