Role of stabilizers for treatment of clayey soil contaminated with phenanthrene through electrokinetic-Fenton process—Some experimental evidences

In electrokinetic-Fenton (EK-Fenton) process, the effects of the phosphate and SDS introduced from the anode chamber were investigated for the treatment of clay contaminated with phenanthrene. In tests with phosphate and SDS, the electrochemical phenomena were complicate trend compared to tests with HCl. These results resulted from complexation of phosphate with oxides and SDS, and then increase of dissolved SDS concentration with pH increase in regions near cathode. The electro-osmotic flow increased as zeta-potential on the soil surface decreased due to complexation of phosphate and SDS with oxides.In test with phosphate, the transportation of dissolved Fe ions toward the cathode was hindered significantly due to complexation with phosphate. However, in test with SDS, the dissolved Fe ions could be transported in the regions near cathode compared to test with phosphate. These results indicate that SDS dissolved the Fe ion from Fe oxide of soil structure and then the dissolved Fe ions with SDS as counter ion could be transported in regions near cathode. Furthermore, transition metal complexation with phosphate and SDS generated improvement of H2O2 stability. Particularly, in test with SDS, the improvement of H2O2 stability in high pH regions resulted from SDS transportation in regions near cathode. Consequently, in EK-Fenton process with longer reaction time, the increase of H2O2 stability resulted in increase of phenanthrene treatment efficiency.