title: Behavior of PAH/mineral associations during thermodesorption: impact for the determination of mineral retention properties towards PAHs.
abstract: Polycyclic aromatic hydrocarbons (PAHs) associated with two minerals (silica sand and bentonite) presenting opposite retention properties were analyzed with a thermodesorption (Td)-GC-MS coupling in order to validate this technique as a new and rapid way to evaluate the solid sorption properties. Two analysis modes were used, evolved gas analysis (EGA) and Td with cryo-trap. EGA allowed a real-time monitoring of the compounds desorbed during a temperature program and gave a first screening of the samples while Td gave more precise indications on compound abundances for selected temperature ranges. When associated with silica sand, PAHs were released at relatively low temperatures (<300 °C) close to corresponding boiling point, whereas for the PAH/bentonite mixture, PAHs were desorbed at much higher temperatures; they were also present in much lower abundance and were associated with mono-aromatic compounds. With bentonite, the PAH abundances decreased and the mono-aromatics increased with the increasing PAH molecular weight. These results indicated a clear PAH retention by the bentonite due to polymerization, followed by a thermal cracking at higher temperatures. The Td-GC-MS was proven to efficiently underline differences in retention properties of two minerals, and this study highlights the great potential of this technique to evaluate compound/matrix bond strength and interaction.
authors.affiliation: Université de Lorraine, LIEC, UMR7360, 54506, Vandœuvre-lès-Nancy, France, coralie.biache@yahoo.fr.
authors.forename: Coralie
authors.initials: C
authors.lastname: Biache
authors.forename: Catherine
authors.initials: C
authors.lastname: Lorgeoux
authors.forename: Alain
authors.initials: A
authors.lastname: Saada
authors.forename: Pierre
authors.initials: P
authors.lastname: Faure
mesh_terms: D001546:Bentonite / Q000032:analysis / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008903:Minerals / Q000032:analysis / Q000737:chemistry; D008970:Molecular Weight; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry*; D012822:Silicon Dioxide / Q000032:analysis / Q000737:chemistry*; D013696:Temperature
chemical_list: D008903:Minerals; D011084:Polycyclic Aromatic Hydrocarbons; D001546:Bentonite; D012822:Silicon Dioxide