Cork-based permeable reactive barriers coupled to electrokinetic processes for interrupting pollutants reaching groundwater: a case study of lead-contaminated soil

Abstract

BACKGROUND: A novel, original and green technology for the remediation of lead-contaminated soil is proposed. The treatment strategy integrates two well-known technologies: electrokinetic (EK) remediation and permeable reactive barriers (PRBs). The novelty of the present work is based on the use of cork granules, as reactive media, in the PRBs for interrupting Pb reaching groundwater. The cork barrier (treatment zone) was emplaced near the anodic compartment to favor the retention and sorption of Pb due to the migration/diffusion effects promoted from soil to the anode during EK remediation. For this purpose, NaNO3 (0.1 mol L−1) and citric acid (0.1 mol L−1) were tested as supporting electrolytes in the cathodic reservoir, while in the anodic compartment a solution of 0.1 mol L−1 NaNO3 was used. Additionally, the influence of direct current and reverse polarity approaches on EK efficiency was evaluated. RESULTS: Results clearly indicated that the novel cork-based PRBs concept was efficient when coupled with EK. Nevertheless, pH conditions played a significant role in Pb sorption by cork granules as well as in the physical–chemical properties of cork under an electrical field. The transportation of Pb by EK, towards the PRB with cork granules, was favored through the use of citric acid in the catholyte and reverse polarity strategy. CONCLUSIONS: These approaches promote a better pH control in the soil and electrode wells, being able to reach near 80% Pb removal from soil, after 14 days of experiment. Therefore, this technology can be used for in situ remediation of Pb-contaminated groundwater. © 2022 Society of Chemical Industry (SCI).