Fenton oxidation of polycyclic aromatic hydrocarbons after surfactant-enhanced soil washing

The feasibility of using a combination of two well-studied technologies-soil washing and Fenton oxidation-to remove polycyclic aromatic hydrocarbons (PAH) from soil and subsequently destroy them in the resulting waste water solution was investigated. Three well-characterized New Jersey soils, representing a wide range of organic carbon content, were artificially contaminated with a mixture of anthracene, phenanthrene, and fluoranthene to simulate PAH-contaminated field soil. Batch laboratory-scale surfactant-enhanced soil washing was used to remove PAH from these soils. Two nonionic octylphenyl ethoxylate-type surfactants-Triton X-100 and Igepal CA-720-were employed. PAH concentration in wash solution containing 1% surfactant was increased by over an order of magnitude above the level possible with water alone. The resulting solutions were treated with Fenton's reagent (H2O2 plus Fe2+) to destroy PAH in solution. Greater than 99% of PAH parent material was destroyed in the Triton X-100 wash solution From the low organic sandy soil. Mass spectrometric analysis of the treated material indicated that partially degraded surfactant molecules constituted the major reaction residuals. The extent of disappearance of parent PAH in soil-washing waste water for a given dose of Fenton's reagent was inversely proportional to the water solubility of the species (anthracene greater than fluoranthene greater than phenanthrene). Surfactant and soil organic matter in spent soil-washing solutions represented significant Fenton's reagent sinks, and would likely be the limiting cost factor in determining the feasibility of this method for a given soil-surfactant system.