Enhanced chemical oxidation of aromatic hydrocarbons in soil systems

Abstract

Fenton’s destruction of benzene, toluene, ethylbenzene, and xylene (BTEX) was investigated in soil slurry batch reactors. The purpose of the investigation was to quantify the enhancement of oxidation rates and efficiency by varying process conditions such as iron catalyst (Fe(II) or Fe(III); 2, 5, and 10 mM), hydrogen peroxide (H 2O 2; 30, 150, 300 mM), and metal chelating agents ( l-ascorbic acid, gallic acid, or N-(2-hydroxyethyl)iminodiacetic acid). Rapid contaminant mass destruction (97% after 3 h) occurred in the presence of 300 mM H 2O 2 and 10 mM Fe(III). An enhanced removal rate (>90% removal after 15 min and 95% removal after 3 h) was also observed by combining Fe(III), N-(2-hydroxyethyl)iminodiacetic acid and 300 mM H 2O 2. The observed BTEX mass removal rate constants (3.6–7.8 × 10 −4 s −1) were compared to the estimated rate constants (4.1–10.1 × 10 −3 s −1). The influence of non-specific oxidants loss (by reaction with iron hydroxides and soil organic matter) was also explored.