Oil hydrocarbons are widespread pollutants in sub-surface sediments with serious threats to terrestrial and aquatic environment. However, very limited data is available about remediation of historically contaminated sediments. This study reports the use of magnetite-catalyzed chemical oxidation (H2O2 and Na2S2O8) to degrade oil hydrocarbons in aged contaminated sediments. For this purpose, oil contaminated sediments were sampled from three different locations in France including two harbors and one petroleum industrial channel. These sediments were characterized by different hydrocarbon index (HI) values (3.7–9.0 g kg−1), total organic carbon contents (1.9%–8.4%) and textures (sand, slit loam and silt). Chemical oxidation was performed in batch system for one week at circumneutral pH by: H2O2 alone, H2O2/Fe(II), H2O2/magnetite, Na2S2O8 alone, Na2S2O8/Fe(II), and Na2S2O8/magnetite. Results obtained by GC-FID indicated substantial hydrocarbon degradation (40–70%) by H2O2/magnetite and Na2S2O8/magnetite. However, oxidants alone or with soluble Fe(II) caused small degradation (<5%). In the presence of H2O2/magnetite, degradation of extractable organic matter and that of HI were highly correlated. However, no such correlation was observed for Na2S2O8/magnetite which resulted in higher removal of HI indicating its selective oxidation behavior. Treatment efficiency was negatively influenced by organic carbon and carbonate contents. For being the first study to report chemical oxidation of oil hydrocarbons in real contaminated sediments, it may have practical implications to design a remediation strategy for target contaminants.
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