2 research outputs found
Characterization and Quantitative Analysis of Single-Walled Carbon Nanotubes in the Aquatic Environment Using Near-Infrared Fluorescence Spectroscopy
Near infrared fluorescence (NIRF) spectroscopy is capable
of sensitive
and selective detection of semiconductive, single-walled carbon nanotubes
(SWNT) using the unique electronic bandgap properties of these carbon
allotropes. We reported here the first detection and quantitation
of SWNT in sediment and biota at environmentally relevant concentrations
using NIRF spectroscopy. In addition, we utilized this technique to
qualitatively characterize SWNT samples before and after ecotoxicity,
bioavailability and fate studies in the aquatic environment. Sample
preparation prior to NIRF analysis consisted of surfactant-assisted
high power ultrasonication. The bile salt sodium deoxycholate (SDC)
enabled efficient extraction and disaggregation of SWNT prior to NIRF
analysis. The method was validated using standard-addition experiments
in two types of estuarine sediments, yielding recoveries between 66
± 7% and 103 ± 10% depending on SWNT type and coating used,
demonstrating the ability to isolate SWNT from complex sediment matrices.
Instrument detection limits were determined to be 15 ng mL<sup>–1</sup> SWNT in 2% SDC solution and method detection limits (including a
concentration step) were 62 ng g<sup>–1</sup> for estuarine
sediment, and 1.0 μg L<sup>–1</sup> for water. Our work
has shown that NIRF spectroscopy is highly sensitive and selective
for SWNT and that this technique can be applied to track the environmental
and biological fate of this important class of carbon nanomaterial
in the aquatic environment
Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments
<p>Adsorption of hydrophobic organic contaminants (HOCs) to black carbon is a well-studied phenomenon. One emerging class of engineered black carbon materials are single-walled carbon nanotubes (SWNTs). Little research has investigated the potential of SWNT to adsorb and sequester HOCs in complex environmental systems. This study addressed the capacity of SWNT, amended to polychlorinated biphenyl (PCB)-contaminated New Bedford Harbor (NBH) sediment, to reduce the toxicity and bioaccumulation of these HOCs to benthic organisms. Overall, SWNT amendments increased the survival of two benthic estuarine invertebrates, <i>Americamysis bahia</i> and <i>Ampelisca abdita</i>, and reduced the accumulation of PCBs to the benthic polychaete, <i>Nereis virens</i>. Reduction in PCB bioaccumulation by SWNT was independent of <i>K</i><sub>ow</sub>. Further, passive sampling-based estimates of interstitial water concentrations indicated that SWNT reduced PCB bioavailability. Results from this study suggest that SWNT are a good adsorbent for PCBs and might be useful for remediation in the future once SWNT manufacturing technology improves and costs decrease.</p