Enhanced Transport of 2,2',5,5'-Polychlorinated Biphenyl by Natural Organic Matter (NOM) and Surfactant-Modified Fullerene Nanoparticles (nC60).

Stable colloidal suspensions of buckminsterfullerene (nC60) in aqueous environments can significantly affect the fate and transport of hydrophobic organic contaminants by serving as a contaminant carrier. In this study, we examined enhanced transport of 2,2',5,5'-polychlorinated biphenyl (PCB) in saturated sandy soil columns by a variety of nC60 samples, including an nC60 sample prepared by the typical solvent exchange method, as well as eight natural organic matter (NOM) or surfactant-modified nC60 samples, prepared by phase-transferring C60 from toluene to an NOM or a surfactant solution. Whereas the NOM- and surfactant-modified nC60 samples have mobility similar to the unmodified nC60, their contaminant-mobilizing capabilities are significantly greater: breakthrough of PCB increases by 47.2 to 227% with the surfactant-modified nC60 samples and by 233 to 370% with the NOM-modified nC60 samples. The significantly enhanced contaminant-mobilizing capability of the modified nC60 is likely due to a combined effect of increased adsorption affinities and increased tendency of desorption nonequilibrium, likely caused by the changes of nC60 aggregation properties induced by the presence of NOM or surfactant. Findings in this study indicate that nC60 formed in different processes might have vastly different effects on contaminant fate and transport. [ABSTRACT FROM AUTHOR]