Electrokinetic Removal of As from Soil Washing Residue

In this study, electrokinetic remediation (EKR) was carried out to remove arsenic (As) from soil washing residue. We screened various processing fluids and found that oxalic acid was most effective for As removal because it reductively dissolved Fe and As from the soil. In EKR, however, NaOH was a more effective agent for removing As, implying that the main removal mechanism of As was ion exchange between OH– and oxyanionic As. Oxalic and citric acid, both of which were efficient agents for removing As in the screening tests, did not effectively remove As by EKR, probably due to the relatively high pH and low soil-to-agent ratio. In EKR, As was mainly removed by electromigration toward the anode, even under high amounts of accumulated electro-osmotic flow. Therefore, strategies that increase electromigration have potential for enhancing As removal.