Role of goethite during air-oxidation of PAH-contaminated soils

Coralie Biache (1) , Olivier Kouadio (1) , Khalil Hanna (2) , Catherine Lorgeoux (3) , Pierre Faure (1)

1 LIEC - Laboratoire Interdisciplinaire des Environnements Continentaux
2 ISCR - Institut des Sciences Chimiques de Rennes
3 GeoRessources

The impact of goethite on air-oxidation of PAH-contaminated soils was studied through two sets of experiments. (i) Soil extractable organic matter (EOM) and (ii) whole coking plant soils were oxidized at 60 and 100 °C for 160 d, with/without goethite. Organic matter (OM) mineralization was monitored via CO2 production and polycyclic aromatic compounds (PACs) oxidation was investigated by GC–MS analyses. The decrease in EOM and PAH contents, and the oxygenated-PAC production observed during EOM oxidation, were enhanced by the presence of goethite. PACs were likely transformed at the goethite surface through electron transfer process. Mass carbon balance revealed a transfer from EOM to the insoluble organic fraction indicating condensation/polymerization of organics. Soil oxidation induced a decrease in EOM, PAH but also in oxygenated-PAC contents, underscoring different oxidation or polymerization behavior in soil. The goethite addition had a lesser impact suggesting that indigenous minerals played an important role in PAC oxidation.

Keywords: Contaminated soil; Polycyclic aromatic compound (PAC); Oxygenated-PAC; Goethite; Oxidation

Domains: Chemical Sciences; Cristallography

Coralie Biache, Olivier Kouadio, Khalil Hanna, Catherine Lorgeoux, Pierre Faure. Role of goethite during air-oxidation of PAH-contaminated soils. Chemosphere, 2014, 117, pp.823-829. ⟨10.1016/j.chemosphere.2014.11.004⟩. ⟨hal-01101620⟩