Facilitated Transport of 2,2′,5,5′-Polychlorinated Biphenyl and Phenanthrene by Fullerene Nanoparticles through Sandy Soil Columns

The potential environmental implications of buckminsterfullerene (C₆₀) and its derivatives have received much attention. In this study, we investigated facilitated transport of 2,2′,5,5′-polychlorinated biphenyl (PCB) and phenanthrene by nC₆₀ (a stable aqueous-phase aggregate of C₆₀) through two sandy soil columns. We found that low-level (from 1.55 to 12.8 mg/L) nC₆₀ could significantly enhance the mobility of PCB and phenanthrene. However, none of the three model dissolved organic matters (DOMs)a humic acid, a fulvic acid, and a bovine serum albuminhad a noticeable effect on the transport of PCB when these DOMs were present at concentrations equivalent to approximately 10−11 mg/L organic carbon. We propose that the contaminant-mobilizing ability of nC₆₀ is a result of irreversible adsorption of a fraction of nC₆₀-associated PCB/phenanthrene (whereas DOM-associated PCB is readily desorbable). Additionally, slow desorption kinetics of nC₆₀-adsorbed PCB/phenanthrene is another possible mechanism. The findings in this study indicate that nC₆₀ in the subsurface environment can greatly enhance the mobility of nonionic, highly hydrophobic organic contaminants, which typically exhibit very low mobility. Such effects should be taken into account when assessing the potential environmental risks of engineered carbonaceous nanomaterials.