Characteristic time determination for transport phenomena during the electrokinetic treatment of a porous medium

Electroremediation is a soil decontamination technique. The electric field applied to a porous medium induces the migration of ionic species in solution. The different phenomena appearing in soil are presented. A new methodological approach is carried out in order to determine if preponderant and/or limiting phenomena can be considered. The theoretical study, using dimensional analysis, showed that transport of ionic species in solution could be described only by electro-osmosis and electromigration phenomena. But, other phenomena, such as heterogeneous reactions, can restrict the migration of ionic species which is only possible for chemical species in solution. Then, an experimental study was carried out with a tracer, in order to verify the theoretical characteristic times for transport phenomena, obtained by dimensional analysis and calculated in a synthetic medium. Rigorous experimental procedures were followed to realise well-controlled electroremediation experiments. The experimental results obtained have allowed the measurement of characteristic times of electrokinetic transport and the theoretical times have been validated. In addition, the application of a simple mass balance equation to the soil and an electrolytic compartment has allowed the verification of the migration behaviour of the mass flux as a front advance. (C) 2002 Elsevier Science B.V. All rights reserved.