Chromate adsorption in a transformed red mud permeable reactive barrier using electrokinesis

DE GIOANNIS, GIORGIA;MUNTONI, ALDO;RUGGERI R;ZIJLSTRA J. P.

2008-01-01

---

Abstract

Electrokinetic removal of chromium from artificially contaminated clayey soil in a bench-scale cell was enhanced by a reactive barrier (RB) of transformed Red Mud (TRM, BAUXSOL) fitted near the anode. When using 0.75 wt% of TRM in a soil spiked up to a Cr (VI) concentration of 1000 mg/kg dry weight, about 54 wt% of total Cr was removed after 6 days, as compared to only 36 wt% from the control cell without TRM RB. Increasing the duration of the treatment up to 12 days and using 1.5 wt% of TRM resulted in the increase of the above mentioned removal efficiencies up to 93 wt% and 57 wt%, respectively. The reduction of Cr (VI) into less mobile Cr (III) was limited by the TRM RB; in fact, lower reduction percentages for the tests with TRM RB as compared to the tests without were observed (respectively, 42% versus 72% for 6 days test, and 60% versus 93% for 12 days test). The obtained results show that Cr (VI) removal efficiency is proportional to the duration of the treatment and enhanced by the development of favorable pHconditions caused by the activity of the anodicTRMRB. It is suggested that electrokinesis may increase the efficiency of metal-oxyanion adsorption on TRM, aswell as that the use of aTRMRBmay improve the efficiency of contaminated soil remediation by means of electrokinesis.