Emission and Collection of Polycyclic Aromatic Hydrocarbons From Raw Asphalt Samples Heated at 130 °C

Abstract

The emission and collection of polycyclic aromatic hydrocarbons (PAHs) in the aqueous solution and asphalt samples obtained from different refineries in Brazil were evaluated. The aqueous solution and asphalt samples were heated under an argon atmosphere at 50 and 130 °C, respectively, for 60 min in a closed system. The targeted PAHs for the aqueous solution were acenaphthene, anthracene, and fluoranthene, while those for the asphalt samples were naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]anthracene. These were all taken from the US EPA list. The performances of Amberlite XAD-2, high-density polyethylene (HDPE), silica (Si), polyurethane foam (PUF), and granular activated carbon (GAC) in collecting the PAHs from the vapor phase by gas–solid adsorption were compared. High-performance liquid chromatography with a diode array detector was used to quantify the mixtures of PAHs retained by the adsorbents. PUF and XAD-2 had the highest PAH retention capacity. For the aqueous solution, PUF showed adsorption yields of 100% for all the investigated PAHs. XAD-2 was also a good adsorbent (adsorption yields >90%), followed by HDPE (75–90% adsorption yields). For silica and GAC, the adsorption yields depended strongly on the PAHs. Alternatively, for the asphalt samples, the adsorption yield decreased dramatically for all the evaluated PAHs, showing that the asphalt matrix had a strong influence on the adsorption capacity of the adsorbents. In this case, the total PAH retention was 47.2% for PUF, 46.8% for XAD-2, 29.9% for GAC, 27.3% for Si, and 19.8% for HDPE. The retention/elution processes on the adsorbent surfaces were also evaluated by atomic force microscopy.