Electrokinetic phenomena in porous media applied to soil decontamination

The feasibility of using electrokinetic phenomena for contaminant removal from low-permeability porous media is investigated by laboratory experiments and theoretical modeling. The main processes by which contaminant transport takes place under a dc electric field in soil are electromigration, electro-osmosis and electrophoresis. They are particularly effective in fine-grained soils, which is not the case for pressure-driven flushing. Meanwhile, although the results of various studies on a laboratory scale suggest that electrokinetics is a promising technology for water soluble contaminant removal, further research is needed at both laboratory and field scales in order to determine the effectiveness of this technology in situ and in the case of non-soluble organic matter such as heavy hydrocarbons. First, this paper describes the electrochemical processes occurring in soil under an electric field. Then the electro-osmosis phenomenon is more particularly investigated in a theoretical and experimental way. Furthermore, the main previous work on the subject is summarized, and experiments conducted in the laboratory on decontamination by electric field of clay samples polluted by motor oil, are presented.