Laboratory-Scale Evaluation of Cr(VI) Removal from Clay by Electrokinetics Incorporated with Fe(O) Barrier

Abstract

The effectiveness of incorporating Fe(O) barrier into electrokinetic (EK) process to remediate Cr(VI) contaminated clay (1,150mg∕kg) was investigated. The EK experiments were conducted using a 12cm long sample under a constant electric gradient of 2V∕cm for 144h. The barrier was installed in the cell and was filled with Fe(O) and silica sand (1:1w∕w). Experimental results showed the removal of Cr from clay was characterized by the high Cr(VI) concentration that occurred in the anode reservoir and the presence of Cr(III) precipitates in the cathode reservoir. The efficiencies of Cr(VI) reduction and total Cr removal for the EK process are 78 and 28%, respectively. As the barrier was installed in the process, a nearly 100% Cr(VI) reduction and 60–70% total Cr removal were achieved. The Cr removal mechanisms were mainly attributed to ion migration and electro-osmotic advection caused by electric gradient. Results indicated that the EK process was enhanced by the reduction of Cr(VI) to Cr(III) by Fe(O) in the barrier. The use of the Fe(O) barrier in EK technology is an effective process for the reduction of Cr(VI) from contaminated clay.