Optical absorption response of chemically modified single-walled carbon nanotubes upon ultracentrifugation in various dispersants |
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| Affiliation: | 1. Instituto de Carboquímica, ICB-CSIC, Miguel Luesma Castán 4, 50018 Zaragoza, Spain;2. Institute for Biocomputation and Physics of Complex Systems, Edificio I + D, University of Zaragoza, Mariano Esquillor s/n, 50018 Zaragoza, Spain;1. State Key Laboratory of Advanced Metallurgy, China;2. School of Metallurgical and Ecological Engineering,, University of Science and Technology Beijing, Beijing 100083, China;1. Central Michigan University, Institute for Great Lakes Research, Biology Department, Brooks Hall 217, Mount Pleasant, MI, 48859, USA;2. Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA;3. Department of Biochemistry and Molecular Genetics, University of Colorado, School of Medicine, Aurora, CO, 80045, USA;4. Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, 867 Lakeshore Rd., Burlington ON, L7S 1A1, Canada |
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| Abstract: | Arc discharge single-walled carbon nanotubes (SWCNTs) were modified through different oxidative treatments and functionalization reactions. The modified SWCNT powders were dispersed in four different aqueous media and purified by ultracentrifugation. Extinction coefficients of the modified SWCNTs depended on the SWCNT type but did not depend on the dispersion medium. According to visible/near infrared spectroscopy, the purity of all the modified SWCNT dispersions substantially improved after ultracentrifugation; however, the spectrum profile, the degree of purity and the centrifugation yield were influenced by the SWCNT type, the surface functional groups and the dispersion medium. Semi-quantitative purity indexes calculated from optical absorption spectra were supported by transmission electron microscopy observations. Contents in metal impurities were analyzed by energy dispersive X-ray spectroscopy. SWCNT samples processed by oxidative acid treatments and ultracentrifugation showed metal contents of lower than 0.5 wt%. |
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