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 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