An experimental study of removal of chromium from contaminated soft soil with the electrokinetic soil flushing method considering temperature and low voltage

Abstract

A series of column tests of chromium-contaminated soft soil were performed in lab using self-designed electrokinetic soil flushing apparatus considering temperature. The changes of the current and electrolyte solution pH, and the effects of the type of leaching agent (i.e. sodium dodecylbenzene sulfonate, citric acid and oxalic acid), applied voltage and temperature on the removal behavior of chromium were analyzed. The results show that chromium in soil can be removed effectively with the electrokinetic soil flushing method. Compared with the single soil flushing method using sodium dodecylbenzene sulfonate (SDS), the removal ratio of Cr(VI) and Cr(total) can increase to 2.79 and 3.12 times when the voltage of 10 V is applied. When the raising temperature increases to 45 ℃, the removal ratio of Cr(VI) and Cr(total) both are greatly improved as citric acid (CA) and oxalic acid (OA) are leaching agents, while the removal ratio of Cr(total) decreases by 4.25% when using SDS as leaching agent. The group using oxalic acid as leaching agent shows the best removal efficiency, and the removal ratio of Cr(VI) and Cr(total) reach 82.08% and 77.57%, respectively. After remediation, the soil structure has changed, and pores between soil particles become smaller and the soils are more compacted.

Keywords

• electrokinetics
• contaminated soft soil
• chromium
• remediation
• temperature