Effect of applied electrical field and the initial soil concentration on species recovery during application of the electroremediation process

Electrokinetic phenomena can be employed for a soil decontamination process generally called electroremediation. The ionic species in solution migrate through a porous medium essentially by electro-osmosis and electromigration. The aim of this work was to contribute to knowledge of this process by studying the effect of some operating conditions on the species recovery through an experimental program. The influence of the electrical field applied to the medium and the initial concentration of the soil solution, in particular, are studied. First, the electrokinetic transport phenomena are presented. Then, the experimental set-up and procedures carried out are described. The set-up consists of a specific electroremediation cell containing a Na-doped kaolinite medium. Chemical reactions were limited by using the sodium as a tracer. The experimental results show the important coupling existing between solution concentration and the electrical current and their influence on both the amount and the rate of transported mass. Moreover, the dependence of the electro-osmotic coefficient on the electrical field applied was demonstrated. The influence of the solution concentration on the electro-osmosis is not obvious, probably due to the light modification of the zeta potential for the system studied.