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

Area of Science:

• Environmental Engineering
• Geochemistry
• Soil Science

Background:

• Chromium contamination in clayey soils poses significant environmental risks.
• Electrokinetic remediation is a promising technique for soil cleanup.
• Transformed Red Mud (TRM) offers potential as a reactive material.

Purpose of the Study:

• To investigate the enhancement of electrokinetic chromium removal from soil using a TRM reactive barrier.
• To evaluate the effect of TRM concentration and treatment duration on chromium removal efficiency.
• To assess the role of TRM in the reduction of Cr(VI) to Cr(III).

Main Methods:

• Bench-scale electrokinetic cell experiments were conducted.
• Artificially chromium-spiked clayey soil was used.
• A reactive barrier of transformed Red Mud (TRM) was installed near the anode.
• Chromium concentrations and Cr(VI) reduction were monitored over time.

Main Results:

• TRM reactive barriers significantly enhanced total chromium removal compared to control cells.
• Removal efficiencies increased with longer treatment durations and higher TRM concentrations.
• TRM limited the reduction of Cr(VI) to Cr(III), suggesting adsorption as the primary removal mechanism.
• Favorable pH conditions near the anode contributed to enhanced removal.

Conclusions:

• TRM reactive barriers effectively improve electrokinetic remediation of chromium-contaminated soils.
• Electrokinesis enhances metal-oxyanion adsorption onto TRM.
• TRM is a viable material for improving soil remediation efficiency.