Effect of Alternative Electrolytes on Enhanced Electrokinetic Remediation of Hexavalent Chromium in Clayey Soil

Abstract

Hexavalent chromium is mobile and hazardous in the environment. Electrokinetic remediation<br />of chromium (IV)-contaminated soils is intended either to remove or to reduce Cr (VI) to Cr (III). This study<br />examines the effectiveness of utilizing EDTA and acetic acid solutions as alternative electrolytes in the<br />electrokinetic (EK) process, with coupled nano-scale zero-valent iron (nZVI) as a barrier for the remediation<br />of Cr (VI)-contaminated clay. An nZVI barrier was installed adjacent to the anode, and different electrolyte<br />solutions (0.1 M EDTA and 1 M acetic acid) were used to investigate the effect of both on the electrokinetic<br />remediation efficiency. Soil was contaminated to 300 ppm of Cr (IV), and a constant DC voltage gradient of<br />1 V/cm was applied to the soil sample for 72 h. It was found that an nZVI permeable reactive barrier (PRB)<br />could improve the Cr (VI) remediation efficiency and reduce electrical energy consumption. Results also<br />showed that acetic acid as electrolyte promoted the reduction of Cr (VI) to Cr (III), while EDTA application<br />as electrolyte led to more chromium removal and reduction than an EK-nZVI barrier.