Removal of PAHs from contaminated clayey soil by means of electro-osmosis
KAUST Grant NumberKUK-C1-017-12
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AbstractThe removal of polycyclic aromatic hydrocarbons (PAHs) from clayey soils is an intricate task. The low porosity of compacted clayey soil hinders bacterial activity and makes convective removal by hydraulic flow impossible. Electro-osmosis is a process that has been used for the mobilization and cleanup of contaminants in clayey soils with varying successes. The present study focuses on the remediation of a contaminated peaty clay soil, located in Olst - the Netherlands, by means of electro-osmosis. The soil was originally contaminated by an asphalt production plant, active from 1903 to 1983, and presents high levels of all 16 priority PAHs indicated by the US Environmental Protection Agency (EPA). Such a long contact times of PAH with the soil (≥100 years) presents a unique study material with well established solid/liquid contaminant partitioning equilibrium, preferable to artificially spiked soil. A batch of 6 electro-osmosis laboratory experiments was carried out to study the removal of 16 PAHs through electro-osmosis. In these experiments, water and a surfactant (Tween 80) were used to enhance the PAH desorption. The electro-osmotic conductivities ranged from 2.88 × 10-10 to a substantial 1.19 × 10-7 m2 V-1 s -1 when applying a current density of 0.005-0.127 A m-2. Electro-osmosis was expected to occur towards the cathode, because of natural soil characteristics (negative zeta potential), but presented scattered directions. The use of reference electrodes proved to be very effective to the prediction of the flow direction. Finally, the addition of Tween 80 as a surfactant enhanced PAH removal up to 30% of the total PAH content of the soil in 9 days. © 2011 Elsevier B.V.
CitationLima AT, Kleingeld PJ, Heister K, Loch JPG (2011) Removal of PAHs from contaminated clayey soil by means of electro-osmosis. Separation and Purification Technology 79: 221–229. Available: http://dx.doi.org/10.1016/j.seppur.2011.02.021.
SponsorsFrank Volkering from TAUW is kindly acknowledged for providing the sample material and information about the contaminated site. Barbel Angres from the Technische Universitat Munchen is kindly acknowledged for the PAH analysis. The authors also thank B. Kuipers from the Department of Chemistry of Utrecht University for zeta potential measurements. This publication was based on work supported by Award No. KUK-C1-017-12, made by King Abdullah University of Science and Technology (KAUST).