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A study of interactions between soil fractions and PAH compounds in thermal desorption of contaminated soils

Authors

  • Vineeta Maguire,

    1. Department of Chemical and Petroleum Engineering, The University of Calgary, Calgary, Alberta T2N 1N4
    Current affiliation:
    1. Amoco Canada Petroleum Co. Ltd., P.O. Box 200, Calgary, Alberta T2P 2H8
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  • William Y. Svrcek,

    1. Department of Chemical and Petroleum Engineering, The University of Calgary, Calgary, Alberta T2N 1N4
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  • Anil K. Mehrotra,

    Corresponding author
    1. Department of Chemical and Petroleum Engineering, The University of Calgary, Calgary, Alberta T2N 1N4
    • Department of Chemical and Petroleum Engineering, The University of Calgary, Calgary, Alberta T2N 1N4
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  • Minoo Razzaghi

    1. TriWaste Reduction Services Inc., 2020, 800 — 5th Avenue S.W., Calgary, Alberta T2P 3T6
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Abstract

The interactions between three polynuclear aromatic hydrocarbons (PAHs), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humin/inorganic fractions, were studied experimentally. Prepared PAH + soil fraction binary mixtures, with PAH concentrations ranging over 0.8–7 mass%, were tested using a differential scanning calorimeter (DSC) over a temperature range of 20−390°C. The DSC thermograms for the PAH + HA mixtures showed distinctly different characteristics compared to mixtures with the other two soil fractions, where the endothermic peak for the vaporization of the PAH was absent. With the aid of vapour-liquid flash calculations, the lack of the boiling point peak is interpreted to be due to the liquid-phase miscibility of the PAHs and the HA fraction. Implications of the DSC results on the design and performance of the thermal desorption process are discussed.

Abstract

On a étudié expérimentalement les interactions de trois hydrocarbures aromatiques polynucléaires (PAH), soient le fluorène le naphtalène et l'anthracène et de trois fractions de sol, soient d'acide fulvique (FA), d'acide humique (HA) et des fractions humiques/inorganiques. Des mélanges binaires de PAH + fraction de sol, avec des concentrations en PAH de 0,8–7% en masse, ont été testés au moyen d'un calorimètre différentiel à balayage (DSC), dans une gamme de températures de 20 à 390°C. Les thermogrammes du DSC pour les mélanges PAH + HA montrent distinctement différentes caractéristiques, comparativement aux mélanges faits à partir des deux autres fractions de sol, là où le pic endothermique correspondant à la vaporisation du PAH est absente. Avec l'aide des calculs de ponts flashs liquide-vapeur, on interprète l'absence de pic de point d'ébullition à la miscibilité en phase liquide des PAH et de la fraction HA. On analyse les implications des résultats du DSC sur la conception et la performance du procédé de desorption thermique.

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