Sorption of Buckminsterfullerene (C_(60)) to Saturated Soils

摘要

With the increasing use of C_(60) in many industrial and commercial sectors, it is likely that it will eventually appear in the environment; however, its environmental fate and transport is still largely unknown. The extent to which C_(60) partitions to soil will contribute to its environmental fate and bioavailability. Because C_(60) is extremely hydrophobic, in this study the distribution between soil and mixtures of ethanol (EOH) and water were measured at ethanol mole fractions ranging from X_(EOH) = 1.0-0.4 for two soils. By measuring K_p at X_(EOH) = 1.0 for a series of soils that ranged in organic carbon and clay mineral content possible mineral contribution to the overall partition process was found for some of the soils. After correcting for any mineral contribution to sorption, the organic carbon normalized partition coefficient K_(oc), at each value of X_(EOH) was calculated from the measured K_(p) values. Through a classical thermodynamic relationship, the K_(oc) values determined at X_(EOH) = 1.0-0.4 were extrapolated to estimate the pure water (i.e., X_(EOH) = 0) K_(oc) value of 10~(7.1)(L/kg|. Accounting for any dissolved organic matter (DOM) in any pure water-soil mixtures may lower this estimate by over a factor of 2, placing this estimate in good agreement with C_(60)'s octanol-water partition coefficient K_(ow) (=10~(6.7)).