The Effect of Time and pH on Improving the Efficiency of the Electrokinetic Method for Remediation of the Soil Contaminated by Chromium

In the recent years, a wide range of contaminated soil by chromium has been reported in the mining and industrial area. Soil contamination by chromium is one of the most important environmental problems that  adversely affects the health of living organisms and human beings. In this regard, electrokinetic is an effective method for soil remediation. This research, aims to investigate the effect of time and pH control on increasing the efficiency of the electrokinetic to remove chromium from contaminated soil. Pourbaix diagram used to interpret the results of experiments. According to the Pourbaix diagram, at pH = 6 trivalent chromium cationic species are dominant at this pH. As a result, these species have been migrated to the cathode. On the anode side, there is also an oxidation environment, which is caused the anionic chromium species transferred and migrated to the anode side. As a result, the phenomenon of electro-migration is the dominant mechanism for the transmission of chromium. At pH less than 7, chromium occurs in the form of cationic species and at pH greater than 7, occurs as anionic or hydroxide species. Results revealed that, reservoir pH control is an acceptable method for increasing chromium extraction efficiency. The results obtained from electrokinetic experiments indicate that this method is more efficient at five days compared to three days. The best removal efficiency of chromium from soil is 68% in 5 days experiment without pH control and 63% in 5 days test with pH control.