Application of magnetite catalyzed chemical oxidation (Fenton-like and persulfate) for the remediation of oil hydrocarbon contamination

Abstract : The chemical oxidative degradation of oil hydrocarbons was investigated by magnetite catalyzed Fentonlike (FL) and activated persulfate (AP) oxidation. An artificial soil composed of silica sand and magnetite was synthesized and characterized by XRD and Mössbauer spectroscopy. This magnetite rich sandy soil (MRS) was then spiked with (i) an organic extract from a soil contaminated by weathered oil (WO) and (ii) a fresh crude oil (CO) and was subjected to oxidation in batch slurry system at circumneutral pH. Experimental results indicate that approximately 70-80% of WO removal was achieved by both FL and AP treatments after one week. Moreover significant CO abatement was also observed by both oxidants (80-90%). Non-selective degradation was evaluated for FL while AP showed less reactivity towards higher molecular weight n-alkanes. Experiments were also conducted with soluble FeII as catalyst instead of magnetite and only 10-15% of degradation was achieved for oxidation experiments with or without soluble FeII addition. Whatever the treatment (FL and AP), no by-products were observed after oxidation experiments which indicate the complete degradation of oil hydrocarbons. Results of this study suggest that magnetite can be used as iron source to activate both Fenton and persulfate oxidation at circumneutral pH. This study has important implications in the remediation of oil polluted soils by FL or AP oxidation.