Feasibility of Using Acetic Acid for Improving Electrokinetic Remediation

The basic scientific understanding acquired in development of electrokinetic remediation technology displays its potential in insitu removal of heavy metals, radionuclides and some organic chemicals from soils. One specific problem associated with the current processing technique is precipitation of the metal close to the cathode as a metal hydroxide. When this precipitate forms a lowly conductive salt, the electrical potential difference across the cell may increase decreasing the efficiency of removal and increasing the cost of remediation. There is a need to devise enhanced processing techniques to remove and/or avoid the precipitate close to the cathode. This study will investigate the use of acetic acid and/or ammonium acetate buffers to circumvent the encountered problem and enhance removal of metals in electrokinetic remediation. There are two advantages to using acetic acid in depolarizing the cathodic processes; (1) most metal acetates are highly soluble and the hydrogen ion is able to depoarize the cathodic electrlysis reaction thereby reducing the energy necessary in electrolysis and avoiding formation of the hydroxide species; (2) migration of an acetate anion upstream will cause formation of neutral acid and hence maintain a lower conductivity due to the association.