Electrokinetic treatment for clayed and sandy soils

Abstract

Electrokinetic treatment has proven to be an attractive alternative to clean polluted soils. This friendly environmental procedure can be approached by a physicochemical model dealing with the oriented displacement of pollutants by means of the fluid and/or charge flow through a porous media induced by an electric field. Concerning the porous media, soil texture is the main issue to consider, since it is related with physicochemical properties that may define the electrokinetic phenomena. In this paper, two different soil textures were tested under the same experimental conditions. Physicochemical characterization of clayed and sandy unpolluted soils, later mixed with PbCO₃, were done. Zeta potential measurements were performed to approach the soil particles interphase with three aqueous solutions. Clayed and sandy soil, mixed with cerusite, were treated by electrokinetics during 24 h. Results for sandy soil contaminated with Pb, using ammonium acetate and acetic acid as anolyte and catholyte respectively, reported Pb mobility due to a fluid flow from anode to cathode; in accordance with zeta potential indicating more negative values for ammonium acetate solution, compared with EDTA and acetic acid. For the clayed soil, lead mobility was detected, even if no electroosmotic flow appeared. Finally, the same experimental conditions were applied to a real soil containing mining wastes, in this case lead mobility was due to electroosmotic and electromigration flow.