Electro-remediation of lead contaminated kaolinite: An electro-kinetic treatment

Abstract

Electroextraction is an innovating separation process which removes in situ heavy metal contained in soil, under the application of an electric field. The paper reports the remediation of kaolinite contaminated with lead by electro-kinetic treatment using a three compartment cell. As a consequence of intensive water dissociation, the high concentration of hydroxyl ions led to precipitation of lead from the soil and formed non-conducting species such as Pb(OH)2. The two chelating agents Citric acid and EDTA are used as anode reservoir to produce protons which exchanged lead cation. Meanwhile, they were also used as cathode reservoir to neutralize hydroxyl anions generated at the electrode, to avoid the formation of the solid species. After seven days, EDTA allowed complete lead removal twice than citric acid, with low energy consumption. The ion migration and the concentration gradient were described by Nernst–Planck equations. In contrast to long period experiments, the ion migration inside the soil progressed from cathode toward anode for short periods. This finding was well supported by pH values.