Measurements of polycyclic aromatic hydrocarbon adsorption on activated carbons at very low concentrations

The aim of this paper is to describe the existent equilibrium between polycyclic aromatic hydrocarbons (PAHs) and granular carbonaceous materials in adsorption processes occurring in carbon beds used for air pollution control. The adsorption of the most volatile PAHs listed by the USEPA-naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene-was measured under the conditions at which they are emitted in energy generation processes, that is, with concentrations ranging from 0.020 to 25 ppm and at a temperature of 150 degreesC. Experimental results show that their adsorption capacity is dependent on PAH concentrations. From the measured adsorption capacities, original isotherms have been plotted and adsorption parameters based on the two-parameter models of Langmuir, Brunauer-Emmett-Teller, Freundlich, and Dubinin-Radushkevich have been calculated. Neither of the two-parameter models was able to fit the experimental data in all PAH concentration ranges studied. Furthermore, no relationship was found between the PAH physical properties-molecular volume, boiling point, and vapor pressure at 150 degreesC-and the parameters obtained in the four models.