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

The feasibility of using a combination of two well-studied technologies-soi l washing and Fenton oxidation-to remove polycyclic aromatic hydrocarbons ( PAH) from soil and subsequently destroy them in the resulting waste water s olution was investigated. Three well-characterized New Jersey soils, repres enting a wide range of organic carbon content, were artificially contaminat ed with a mixture of anthracene, phenanthrene, and fluoranthene to simulate PAH-contaminated field soil. Batch laboratory-scale surfactant-enhanced so il washing was used to remove PAH from these soils. Two nonionic octylpheny l 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. Th e resulting solutions were treated with Fenton's reagent (H2O2 plus Fe2+) t o destroy PAH in solution. Greater than 99% of PAH parent material was dest royed in the Triton X-100 wash solution From the low organic sandy soil. Ma ss 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 gi ven dose of Fenton's reagent was inversely proportional to the water solubi lity of the species (anthracene greater than fluoranthene greater than phen anthrene). Surfactant and soil organic matter in spent soil-washing solutio ns represented significant Fenton's reagent sinks, and would likely be the limiting cost factor in determining the feasibility of this method for a gi ven soil-surfactant system.