Remediation of clay soil contaminated with lead nitrate using washing-enhanced electrokinetic technique

Abstract

The remediation of clay soil contaminated with lead nitrate has been investigated in details by using the electrokinetic technique enhanced by using purging solutions, mid compartment, and washing technique. The intact soil samples are obtained from Al-Ahdab oil field located in the southeast of Iraq. The soil samples are contaminated synthetically with two different percentages of lead nitrate (6.67 and 20g/kg) and kept for 30 days. The mid compartment is used to reduce the existing paths of contaminants from the soil. Purging solutions in the anode, mid, and cathode compartments are used to control the pH value, while the activated carbon is used to prevent the reverse electroosmotic flow from cathode to anode. The main results of electrokinetic experiments, such as variations of electrical current and pH with time, and the accumulated volume of electroosmotic flow are presented and discussed. It is shown that increasing of the concentration of lead causes increase of the electrical current generated during the remediation process. As a consequence, the intensity of chemical reactions occurring in the anode, mid, and cathode compartments are also increased. The removal efficiency of lead from soil samples ranged between 12.4 and 21 %. The washing process is found beneficial in reducing the period of remediation but does not affect the removal efficiency.