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Download fileImpact of Sunlight and Humic Acid on the Deposition Kinetics of Aqueous Fullerene Nanoparticles (nC60)
journal contribution
posted on 2012-12-18, 00:00 authored by Xiaolei Qu, Pedro J.J. Alvarez, Qilin LiNanoparticle transport in natural settings is complex
due to interactions
with the surrounding environment. In this study, the impact of UVA
irradiation and humic acid (HA) on deposition of aqueous fullerene
nanoparticles (nC60) on a silica surface as a surrogate
for natural sediments was studied using packed column experiments
and quartz crystal microbalance with dissipation monitoring under
various solution conditions. Surface oxidation of nC60 induced
by UVA irradiation greatly retarded its deposition due to the increased
negative surface charge and hydrophilicity. Dissolved HA, once adsorbed
onto the nC60 surface, also hindered its deposition mainly
through steric hindrance forces. The extent of this effect depended
on the properties and the amount of HA adsorbed, which is a function
of ionic strength and HA concentration. HA has limited adsorption
on UVA-irradiated nC60 and is expected to play a less important
role in its stability. HA immobilized onto the silica surface had
a variable effect on nC60 deposition, depending on the
complex interplay of Derjaguin–Landau–Verwey–Overbeek
(DLVO) and non-DLVO interactions such as electrostatic interaction,
steric hindrance, and hydrogen bonding as well as HA molecular conformation.
These results highlight the importance of environment-induced changes
in nC60 surface chemistry in its fate and transport in
aquatic environments.