Application of a multi-electrode system with polyaniline auxiliary electrodes for electrokinetic remediation of chromium-contaminated soil

In this study, a polyaniline (PANI) composite supported by nonwoven fabric was synthesized and applied as an auxiliary electrode in conventional electrokinetic remediation for the first time to investigate the effectiveness of the multi-electrode system in remediating Cr-contaminated soil. Firstly, PANI was successfully combined with nonwoven fabric and has a good adsorption performance for chromium (VI) in aqueous solution, which is highly dependent on the pH of the solution. Then a series of electrokinetic experiments with four different auxiliary electrode configurations were conducted to evaluate Cr (VI) removal and its migration behavior. The results show that the Cr (VI) removal can be up to 20% higher than that of the conventional electrokinetic remediation with the existence of auxiliary electrode. And the mechanism about it was the combined effect of electromigration and the adsorption of PANI. The role of PANI auxiliary electrode was more than an adsorbent, but also an accelerator for Cr (VI) migration to the anode, which means it can intercept and adsorb the heavy metal ions passed through during strengthening the electrolysis process. The acidic environment of anode is more favorable for PANI auxiliary electrode's adsorption, but the most effective and economical arrangement about it was on the cathode side with less energy consumption of 115 kWh/g. Because the effect of the particle acceleration of the PANI auxiliary electrode was greater than that of the adsorption. This multi-electrode system should also be applicable for the removal of anionic chemicals from contaminated soils.