Contaminant extractability by electrokinetics

Electrokinetic extraction is an emerging technology that has shown considerable potential for efficient and effective removal of both inorganic and organic contaminants from fine-grained soils of low hydraulic conductivity and large specific area when conditions are favorable. The cleanup technology is basically the application of a direct-current electric field across contaminated soils through electrodes installed in the subsurface. The contaminant is removed by (1) electro-osmotic advection of pore fluid flushing the contaminants; (2) ionic migration or electromigration of contaminants carrying charges; and (3) electrophoresis of charged colloidal-sized particles carrying contaminants. However, many complicated electrochemical phenomena that can change the electrokinetic properties of soil particles and the chemistry of pore fluid occur simultaneously. The resulting soil-chemical interactions may enhance or inhibit the extractability of contaminants by electrokinetics, as various electrochemical processes are dynamic, reversible, and interdependent. The impacts of these phenomena on contaminant extractability by electrokinetics are discussed in this paper. A comprehensive list of useful references on electrokinetic extraction is also included for use by readers interested in the subject.