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

Document Type: Original Research Paper

Authors

1 School of Civil Engineering, Iran University of Science and Technology, Narmak, 16846, Tehran, Iran. 2Department of Civil Engineering, The University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia V6T 1Z4, Canada

2 Department of Civil Engineering, The University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia V6T 1Z4, Canada

3 Post graduate, Department of Civil Engineering, University of Massachusetts Dartmouth, North Dartmouth, MA 02747-2300, USA

Abstract

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

Keywords