Remediation of a PAH-contaminated soil by oxidation with fenton reagment and simultaneous solubilization with surfactants

MARINA PELUFFO; FERNANDO PARDO PARDO; AURORA SANTOS; ARTURO ROMERO

Barcelona

Congreso; 13th Mediterranean Congress of Chemical Engineering; 2014

With the purpose of increase the effectiveness of In Situ Chemical Oxidation techniques, the combination of them, concurrently or sequentially with surfactants, has been of growing interest in the field of soil and groundwater remediation. By using ISCO techniques, a wide range of organic contaminants can be oxidized, but taking into account that reactions take place in the aqueous phase, the low solubility of pollutants limit the extent of the remediation techniques. The presence of surfactants result in a decrease of surface tension and increase the availability of the contaminant in the aqueous phase (Dugan et al., 2010), permitting them to be more easily degraded. A sandy loam soil was spiked artificially with 100 mg?kg-1each of 4 PAH, Anthracene (3 rings), Phenanthrene (3 rings), Pyrene (4 rings) and Benzo(a)Pyrene (5 rings), which are included in the list of 16 PAHs priority pollutants. Fenton and Fenton reagent coupled with surfactant (Sodium dodecyl sulfate) were used, with ferrous sulfate as the catalyst specie ([H2O2] = 880 mmol?L-1, [Fe] = 1 mmol?L-1, [SDS] = 7.64 mmol?L-1). Reactions were conducetd without pH adjustement, using PTFE 50 mL centrifuge tubes as reactors, stirred isothermally at 20 ºC in an orbital shaker. Ratio selected for aqueous phase to soil was 2 mL?g-1. It has been studied the removal efficiency of every pollutant (Anthracene, Phenanthrene, Pyrene and Benzo(a) pyrene) with conventional Fenton reagent and surfactant enhanced Fenton reagent . Besides, the evolution of the different species (oxidant, surfactant, total iron in solution and contaminant) as well as pH, was followed during the reaction time and the identification of oxidation products and intermediates was carried out. It was found that natural pH of the slurries was slightly acidic at the experimental conditions, (around pH = 5). Regarding to contaminat removal, it was observed a faster consumption of Anthracene and Benzo(a)pyrene than Phenanthrene and Pyrene. Surfactant was oxidized progressively with reaction time, but in spite of this fact, removal efficiencies at the final reaction time were higher when reactions where conducted in the presence of surfactant.