Despite its extremely low solubility in water, fullerite C₆₀ can form colloidally stable aqueous suspensions containing nanoscale C₆₀ particles (nC₆₀) when it is subject to contact with water. nC₆₀ is the primary fullerene form following its release to the environment. The aim of the present study was to provide fundamental insights into the properties and environmental impacts of nC₆₀. nC₆₀ suspensions containing negatively charged and heterogeneous nanoparticles were produced via extended mixing in the presence and absence of citrate and other carboxylates. These low-molecular weight acids were employed as simple surrogates of natural organic matter. The properties of nC₆₀ were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV-Vis spectroscopy. nC₆₀ produced in the presence of carboxylate differs from that produced in water alone (aq/nC₆₀) with respect to surface charge, average particle size, interfacial properties, and UV-Vis spectroscopic characteristics. Importantly, regularly shaped (spheres, triangles, squares, and nano-rods) nC₆₀ nanoparticles were observed in carboxylate solutions, but not in water alone. This observation indicates that a carboxylate-mediated 'bottom-up' process occurs in the presence of carboxylates. Changes in the UV-Vis spectra over time indicate that reactions between C₆₀ and water or other constituents in water never stop, potentially leading to significant morphologic changes during storage or as a result of simple dilution. These results suggest that studies examining the transport, fate, and environmental impacts of nC₆₀ should take the constituents of natural waters into consideration and that careful examination on the properties of the tested nC₆₀ should be conducted prior to and during each study. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/77152 |
| Date | 08 September 2011 |
| Creators | Chang, Xiaojun |
| Contributors | Environmental Engineering, Vikesland, Peter J., Morris, John R., Little, John C., Marr, Linsey C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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