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Light-Induced Transformations of the C60 Derivative, Fullerenol: Interactions with Natural Organic Matter
Citation:
ZEPP, R. G., L. Kong, K. Chan, AND O. Tedrow. Light-Induced Transformations of the C60 Derivative, Fullerenol: Interactions with Natural Organic Matter. Presented at 238th ACS National Meeting & Exposition, Washington, DC, August 16 - 20, 2009.
Impact/Purpose:
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Description:
Recent studies have indicated that fullerenes, an important class of nanomaterials, are photodegraded by solar radiation and can sensitize the photoproduction of reactive oxygen species such as singlet oxygen. Because natural organic matter (NOM) can retard photoreactions that are sensitized by buckminsterfullerene (C60), it was concluded that association of fullerenes with NOM increases the environmental persistence of this class of nanomaterials. Results from this study contradict this conclusion in part by showing that NOM (in the 2 to 4 mg C/L range) enhances the photodegradation of fullerenol, a hydrophilic, hydroxylated derivative of C60. Evidence is provided that fullerenol can be extensively mineralized under environmental conditions by a combination of direct and NOM-sensitized photolysis and post-irradiation bacterial respiration of labile photoproducts of the fullerenol. Dissolved inorganic carbon (DIC) was identified as the major photoproduct in the pH 4 to 7 range and the ratio of moles of DIC produced to moles of fullerenol reacted reached 26 or approximately 47% of complete mineralization at the end of 90 hrs of exposure to simulated solar radiation. Rose Bengal did not efficiently photosensitize the oxidation of fullerenol, indicating that singlet oxygen probably is not directly involved in the NOM-enhanced photoreactions of fullerenol.