Influence of polarity exchange frequency on electrokinetic remediation of Cr-contaminated soil using DC and solar energy

Electrokinetic remediation (EKR) is a remediation method that can effectively remove heavy metals from soil. Traditional EKR uses an external power source to consume electrical energy, in the present study, through the experiment of different electrode exchange frequency to remediate Cr contaminated soil, the effect of polarity exchange electric remediation and the influencing factors of Cr(VI) to Cr(III) conversion are discussed. Five experiments were conducted using DC power supply with conventional EKR (T1), DC power supply with polarity exchange EKR (T2, T3) and solar energy with EKR (T4, T5). The results showed that the T1 experiment had the maximum removal rate of total Cr (42.03 %) and Cr(VI) (85.50 %) but had an adverse effect on soil pH. T2, which exchanged polarity every 24 h, and T3, which exchanged polarity after 84 h, had smaller adverse effects on soil pH, but the removal efficiency was reduced due to repeated migration. The reduction of Cr(VI) to Cr(III) occurred during the EKR processes, the content of Cr(III) increased greatly. Furthermore, few differences were observed between DC power and solar power on the EKR experiments. Therefore, the combination of electrokinetics and solar energy is a feasible method for Cr-contaminated soil. (c) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.