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

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.