Abstract
The removal of oxidation debris from the oxidized carbon nanotube
surface with a NaOH treatment is a key step for an effective
functionalization and quality improvement of the carbon nanotube
samples. In this work, we show via infrared spectroscopy and ultrahigh
resolution and accuracy mass spectrometry that oxidation debris obtained
from HNO3-treated multiwalled carbon nanotubes is a complex mixture of
highly condensed aromatic oxygenated carbonaceous fragments. We have
also evaluated their cytotoxicity by using BALB/c 3T3 mouse fibroblasts
and HaCaT human keratinocytes as models. By knowing the negative aspects
of dissolved organic carbon (DOC) to the water quality, we have
demonstrated the removal of these carbon nanotube residues from the NaOH
solution (wastewater) by using aluminium sulphate, which is a standard
coagulant agent used in conventional drinking water purification and
wastewater treatment plants. Our results contribute to elucidate the
structural and proactive safety aspects of oxidation debris from
oxidized carbon nanotubes towards a greener nanotechnology. (C) 2011
Elsevier B.V. All rights reserved.
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