Efficient removal of chromium from soil in a modified electrokinetic system using iron-treated activated carbon as third electrode

摘要

A modified electrokinetic remediation (EKR) system was designed to remediate Cr-contaminated soil by using iron-treated activated carbon (AC) as the third electrode. Controlled and orthogonal experiments were conducted with aim of evaluating effect of various factors on Cr removal in this modified system. The results revealed that remediation time was most influential on removal capacity of the three-dimensional (3D) electrode EKR system. The existence of particle electrodes buffered soil pH and the average removal efficiency of Cr(VI) was enhanced to 50.09% after 5 days compared with 42.49% by conventional EKR. Noticeably, the removal rate of Cr(VI) was enhanced to 86.46% after 10 days remediation at particle electrode of 2 mm. Besides, it was found that 3D electrode EKR system were effective to carbonates and exchangeable fraction of Cr by reducing/converting Cr(VI) to Cr(III) or more stable compounds. In addition to prevailing electromigration, the main removal mechanism in modified EKR system was adsorption/electrosorption of third electrode and substantial conduction of Cr(VI) in soil. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.