Mercury-Contaminated Soil Remediation by Iodide and Electroreclamation

Mercury was removed from a field-contaminated soil by a combination of redox and complexation processes with iodide/iodine and electrokinetic mobilization. Iodide added to the cathode compartment was transported into the soil and oxidized to iodine near the anode. Mercury was mobilized and transported to the anode as a mercury-iodide complex. After 5 days, some 50% of the total mercury content had migrated to the anode compartment, and another 25% was recovered from the soil water in the vicinity of the anode. No volatile mercury was formed. Electromigration is the dominant transport process for the (charged) mercury-iodide complex, since electro-osmosis would have moved the mercury toward the cathode. The combination of iodide as complexing agent and an electric field for physical mobilization could be developed to a new method for in situ remediation of mercury contaminated soil.