Impacts of some environmentally relevant parameters on the sorption of polycyclic aromatic hydrocarbons to aqueous suspensions of fullerene.

The wide application of engineered carbon nanomaterials (CNMs), such as fullerene (C60), inevitably will result in their introduction into the aqueous environment. It is likely CNMs will associate with abundant natural organic matter (NOM) and engineered surfactants to form stable aqueous suspensions through various environmental processes. The present study reveals that sorption of polycyclic aromatic hydrocarbons (PAHs) to fullerene resulted in a remarkable decline of freely dissolved PAH concentrations. For the three PAHs studied (phenanthrene, fluoranthene, and chrysene) with log K(ow) in the range of 4.56 to 5.81, the measured sorption coefficients to aqueous suspensions of fullerene (log K(C60) = 4.71-5.48) were close to that of dissolved organic carbon (DOC) from Aldrich humic acid (log K(DOC) = 4.48-5.91). Aqueous suspensions of fullerene were stable for a wide range of pH (3.0-11.0) and salinity conditions (0-25 mM NaCl), and the pH and salinity had minor effects on the sorption of PAHs to aqueous suspensions of fullerene. The addition of humic acids (5 mg/L DOC) to the fullerene (5 mg/L) suspensions resulted in an additional reduction of freely dissolved PAH concentrations. The high PAH sorption coefficients to suspended fullerene suggest that the release of fullerene to the aquatic environment might affect PAH fate and exposures.