| Photoreactivity of carboxylated single-walled carbon nanotubes in sunlight: reactive oxygen species production in water. | |
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MedLine Citation:
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PMID: 20687543 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Very limited information exists on transformation processes of carbon nanotubes in the natural aquatic environment. Because the conjugated pi-bond structure of these materials is efficient in absorbing sunlight, photochemical transformations are a potential fate process with reactivity predicted to vary with their diameter, chirality, number and type of defects, functionalization, residual metal catalyst and amorphous carbon content, and with the composition of the water, including the type and composition of materials that act to disperse them into the aqueous environment. In this study, the photochemical reactions involving colloidal dispersions of carboxylated single-walled carbon nanotubes (SWNT-COOH) in sunlight were examined. Production of reactive oxygen species (ROS) during irradiation occurs and is evidence for potential further phototransformation and may be significant in assessing their overall environmental impacts. In aerated samples exposed to sunlight or to lamps that emit light only within the solar spectrum, the probe compounds, furfuryl alcohol (FFA), tetrazolium salts (NBT2+ and XTT), and p-chlorobenzoic acid (pCBA), were used to indicate production of 1O2, O2.-, and .OH, respectively. All three ROS were produced in the presence of SWNT-COOH and molecular oxygen (3O2). 1O2 production was confirmed by observing enhanced FFA decay in deuterium oxide, attenuated decay of FFA in the presence of azide ion, and the lack of decay of FFA in deoxygenated solutions. Photogeneration of O2.- and .OH was confirmed by applying superoxide dismutase (SOD) and tert-butanol assays, respectively. In air-equilibrated suspensions, the loss of 0.2 mM FFA in 10 mg/L SWNT-COOH was approximately 85% after 74 h. Production of 1O2 was not dependent on pH from 7 to 11; however photoinduced aggregation was observed at pH 3. |
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Authors:
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Chia-Ying Chen; Chad T Jafvert |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Environmental science & technology Volume: 44 ISSN: 1520-5851 ISO Abbreviation: Environ. Sci. Technol. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-08-30 Completed Date: 2010-12-20 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0213155 Medline TA: Environ Sci Technol Country: United States |
Other Details:
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Languages: eng Pagination: 6674-9 Citation Subset: IM |
Affiliation:
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Purdue University, School of Civil Engineering, West Lafayette, Indiana 47907, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Carboxylic Acids
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chemistry* Chlorobenzoates / chemistry Furans / chemistry Hydrogen-Ion Concentration Nanotubes, Carbon / chemistry* Reactive Oxygen Species / chemistry* Singlet Oxygen / chemistry Sunlight* Tetrazolium Salts / chemistry Thioinosine / analogs & derivatives, chemistry Water / chemistry* |
| Chemical | |
Reg. No./Substance:
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0/Carboxylic Acids; 0/Chlorobenzoates; 0/Furans; 0/Nanotubes, Carbon; 0/Reactive Oxygen Species; 0/Tetrazolium Salts; 117038-70-7/2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; 17778-80-2/Singlet Oxygen; 38048-32-7/4-nitrobenzylthioinosine; 574-25-4/Thioinosine; 74-11-3/4-chlorobenzoic acid; 7732-18-5/Water; 98-00-0/furfuryl alcohol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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