Effect of H₂SO₄ and HCl in the anode purging solution for the electrokinetic-Fenton remediation of soil contaminated with phenanthrene

Abstract

The Electrokinetic-Fenton (EK-Fenton) process is a powerful technology to remediate organic-contaminated soil. The behavior of salts and acids introduced for the pH control has significant influence on the H₂O₂ stabilization and destruction of organic contaminants. In this study, the effects of the type and concentration of acids, which were introduced at the anode, were investigated for the treatment of clayey soil contaminated with phenanthrene. In experiments with H₂SO₄ as the anode solution, H₂O₂ concentration in the anode reservoir decreased due to reaction between reduced species of sulfate and H₂O₂, as time elapsed. By contrast, HCl as an electrolyte in the anode reservoir did not decrease the H₂O₂ concentration in the anode reservoir. The reaction between the reduced species of sulfate and H₂O₂ hindered the stabilization of H₂O₂ in the soil and anode reservoir. In experiments with HCl for pH control, Cl^·, and Cl₂ ^{· −}, which could be generated with mineral catalyzed Fenton-like reaction, did not significantly hinder H₂O₂ stabilization. H₂O₂ transportation with electro-osmotic flow and mineral catalyzed Fenton-like reaction on the soil surface resulted in the simultaneous transport and degradation of phenanthrene, which are dependent of the advancement rate of the acid front and electro-osmotic flow toward the cathode according to HCl and H₂SO₄ concentrations in the anode purging solution.

Keywords:

• Electrokinetic Fenton process
• inorganic radicals
• Fenton-like reaction
• hydrophobic organic contaminant
• mineral catalysis