Remediation of a Diesel-Contaminated Soil Using a Fenton-Like Advanced Oxidation Process: Optimization by Response Surface Methodology

Abstract

Magnetite, a naturally occurring mineral of iron oxide, and zero-valent iron (ZVI) were used to catalyze hydrogen peroxide and initiate a dark Fenton-like reaction of diesel-contaminated loamy sand in a batch system at circumneutral pH. The effects of hydrogen peroxide concentration and catalyst content on the removal efficiency of total petroleum hydrocarbons (TPHs) were studied. A central composite rotatable design was applied and the derived equation for magnetite and ZVI were linear and quadratic, respectively. In both equations, the factor of hydrogen peroxide concentration was more significant than catalyst content. At optimum conditions (4.27 wt% of catalyst content and 2.17 mol/L of hydrogen peroxide), 57% and 67% of TPH removal were achieved by magnetite and ZVI, respectively. The obtained results suggest the potential of ZVI and magnetite to catalyze a heterogeneous Fenton-like reaction at circumneutral pH. It seems that using ZVI, rather than magnetite, as a catalyst may result in slightly more TPH mineralization; however, since magnetite is a naturally occurring mineral, it may be able to compete economically with ZVI.