25th International Meeting on Organic Geochemistry IMOG 2011

P-386
Remediation of hydrocarbon contaminated soils by modified
Fenton oxidation in the presence of magnetite
Usman Muhammad 1,2 , Faure Pierre 1 , Hanna Khalil 2 , Ruby Christian 2
1 UMR CNRS G2R Nancy Université, Vandoeuvre les Nancy, France, 2 UMR CNRS LCPME Nancy
Université, Villers les Nancy, France (corresponding author:pierre.faure@g2r.uhp-nancy.fr)
The intense use of fossil organic matter (petroleum
and coal) since 18 th century for industrial purposes
(petroleum extraction, refinery, steel industries, coking
plant etc.) has resulted in numerous contaminated
sites that cause environmental and health concerns.
Especially, polycyclic aromatic hydrocarbons (PAHs),
well known carcinogenic pollutants, are resistant to
environmental degradation and imply huge industrial
treatments (e.g. thermal desorption…). On the
contrary, petroleum hydrocarbons are easily
biodegradable by soil microorganisms or by biological
treatments. However, refractory fractions (especially
asphaltenes) remain difficult to eliminate and can
induce major perturbation of flora and fauna in the
environment.
In situ chemical oxidation (ISCO) especially Fenton
oxidation can be a potential remediation processes
susceptible to degrade these recalcitrant organic
compounds. Instead of applying traditional Fenton
oxidation (dissolved Fe II + H2O2, optimal pH 3-4),
modified Fenton oxidation was developed in this study
by using iron minerals which allows the oxidation at
circumneutral pH. Indeed, soil iron minerals
containing both Fe II -Fe III are more reactive but rare in
soil system than only Fe III minerals which are
abundant. Firstly endogenous soil Fe III minerals were
transformed into magnetite (Fe II Fe III 2O4), a more
reactive phase, so that it can be used as an iron
source to promote oxidation of pollutants.
Then the kinetic degradation of i) Fluorenone (model
pollutant of PAHs) ii) Organic extract from a PAHs
polluted soil from an industrial site, iii) n-Eicosane
(model pollutant of petroleum) iv) Organic extract from
a petroleum contaminated soil was investigated
through modified Fenton oxidation. All experiments
were conducted in batch reactors with magnetite rich
sand at circumneutral pH.
Almost 90% of fluorenone abatement was achieved
after 48 hours of reaction with H2O2 in the presence of
magnetite and no pollutant traces were detected after
one weak. Significant degradation (81%) of 16 PAHs
was found in case of PAHs polluted soil (Fig. 1).
Almost 90% and 85% of n-eicosane and petroleum
hydrocarbons respectively was degraded after one
week (Fig. 1). Also no by-products were observed
through GC-MS analysis for model compounds as
well as for organic extracts which indicates the
complete oxidative degradation of pollutants. In
parallel, the FTIR analysis shows no modification of
the molecular structure (especially oxygenated
functions) for all organic samples. Moreover, a nonselective
degradation was revealed for all
contaminants as no molecule was preferably
degraded.
Figure 1: Abatement of pollutants with the course of
time represented in terms of C/C0 where C0 is initial
pollutant concentration and C is the concentration at
specified time point.
Currently oxidation experiments are in process on real
soil. This study has important implications in the
remediation of polluted soils by using the reactivity of
soil endogenous iron which can be used as a feasible
source of iron catalyst to promote modified Fenton
oxidation. Moreover, this chemical treatment should
be carried out in situ avoiding soil excavation.
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