posted on 2014-09-02, 00:00authored byZhichong Qi, Lei Hou, Dongqiang Zhu, Rong Ji, Wei Chen
With
the increasing production and use of graphene oxide, the environmental
implications of this new carbonaceous nanomaterial have received much
attention. In this study, we found that the presence of low concentrations
of graphene oxide nanoparticles (GONPs) significantly enhanced the
transport of 1-naphthol in a saturated soil, but affected the transport
of phenanthrene to a much smaller extent. The much stronger transport-enhancement
effect on 1-naphthol was due to the significant desorption hysteresis
(both thermodynamically irreversible adsorption and slow desorption
kinetics) of GONP-adsorbed 1-naphthol, likely stemmed from the specific
polar interactions (e.g., H-bonding) between 1-naphthol and GONPs.
Increasing ionic strength or the presence of Cu(II) ion (a complexing
cation) generally increased the transport-enhancement capability of
GONPs, mainly by increasing the aggregation of GONPs and thus, sequestering
adsorbed contaminant molecules. Interestingly, modifying GONPs with
Suwannee River humic acid or sodium dodecyl sulfate had little or
essentially no effect on the transport-enhancement capability of GONPs,
in contrast with the previously reported profound effects of humic
acids and surfactants on the transport-enhancement capability of C60 nanoparticles. Overall, the findings indicate that GONPs
in the aquatic environment may serve as an effective carrier for certain
organic compounds that can interact with GONPs through strong polar
interactions.