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 remediationof chromium (IV)-contaminated soils is intended either to remove or to reduce Cr (VI) to Cr (III). This studyexamines the effectiveness of utilizing EDTA and acetic acid solutions as alternative electrolytes in theelectrokinetic (EK) process, with coupled nano-scale zero-valent iron (nZVI) as a barrier for the remediationof Cr (VI)-contaminated clay. An nZVI barrier was installed adjacent to the anode, and different electrolytesolutions (0.1 M EDTA and 1 M acetic acid) were used to investigate the effect of both on the electrokineticremediation efficiency. Soil was contaminated to 300 ppm of Cr (IV), and a constant DC voltage gradient of1 V/cm was applied to the soil sample for 72 h. It was found that an nZVI permeable reactive barrier (PRB)could improve the Cr (VI) remediation efficiency and reduce electrical energy consumption. Results alsoshowed that acetic acid as electrolyte promoted the reduction of Cr (VI) to Cr (III), while EDTA applicationas electrolyte led to more chromium removal and reduction than an EK-nZVI barrier.