Surfactant-Enhanced Electrokinetic Remediation of Chromium and Phenanthrene Cross-Polluted Soils

摘要

Electrokinetic (EK) remediation has potential to simultaneously remove heavy metals (HMs) and organic compounds from soil, but removal efficiency of these pollutants is very low in general if no enhancing treatment is applied. In this work, a new enhanced EK remediation technology to decontaminate a HM-organic cross-contaminated soil by applying different surfactants and pH control were studied. Laboratory-scale EK experiments were performed using different surfactants (Triton X-100, Tween 80, and Dowfax 8390) and controlling catholyte electrolyte pH at 4. Diphenylcarbazide (DPC), which is a complexing agent used in the spectrophotometric determination of chromate, was used as a solubilizer for chromium (Cr). After treatment with 1.0V/cm of voltage gradient for 15 days, soil pH, electroosmotic flow (EOF), electrical current, and the concentrations and chemical fractionations of soil phenanthrene (PHE) and Cr were analyzed. Results indicated that EOF rate in the Dowfax 8390 system was higher than other surfactants. Using EK technology for removal of Cr and PHE in the presence of Dowfax 8390 was more efficient than in the presence of other surfactants. A surfactant system containing both Dowfax 8390 and solubilized DPC is the most effective surfactant system to remediate Cr-contaminated soil in EK treatment. However, to a certain extent, the removal efficiency of PHE is reduced. In addition, the influence of pH in this system was evaluated. Under the optimal operating conditions, more than 70%, 86%, and 56% of Cr(T), Cr6+, and PHE were removed from the soil, respectively. Overall, it can be concluded that the enhanced EK remediation system in the simulated setup can be effective for the removal of both HMs and polycyclic aromatic hydrocarbons from clayey soils and will help develop the remediation technology for HM-organic cross-contaminated soil.