Sorption of pyrene by regular and nanoscaled metal oxide particles: influence of adsorbed organic matter.

Sorption of pyrene by regular and nanoscaled aluminum, zinc, and titanium oxides was examined. All oxides had low sorption for pyrene because of sorbed water molecules. Due to the larger surface area (SA) of nanoparticles, they had higher sorption for pyrene than the regular ones. Organic matter (OM) coating greatly enhanced pyrene sorption by all oxides, noting the importance of sorbed OM in sorption of hydrophobic organic compounds (HOCs). Due to higher sorption site density in the sorbed OM phase on the regular oxide surfaces, SA-normalized distribution coefficients (K(dSA)) of pyrene by OM-regular oxide complexes (6.0-40.6) were greater than the OM-coated oxide nanoparticles (0.7-12.5). Furthermore, the OM-regular oxide complexes had higher organic carbon content-normalized K(dSA) values of pyrene (48-17 300) than the OM-nanoscaled oxide complexes (15-1530). This variation may be due to different physical forms and fractionation of the loaded OM on regular and nanoscaled oxide particles.