Application of Centrifugation to the Large-Scale Purification of Electric Arc-Produced Single-Walled Carbon Nanotubes
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- 作者：Aiping Yu ; Elena Bekyarova ; Mikhail E. Itkis ; Danylo Fakhrutdinov ; Robert Webster ; Robert C. Haddon
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：August 2, 2006
- 年：2006
- 卷：128
- 期：30
- 页码：9902 - 9908
- 全文大小：656K
- 年卷期：v.128,no.30(August 2, 2006)
- ISSN：1520-5126
文摘
We report a further advance in the bulk purification of nitric acid-treated single-walled carbonnanotubes (SWNTs) by use of high-speed centrifugation. We have already shown that low-speedcentrifugation is effective in removing amorphous carbon (AC). In these earlier experiments, the ACpreferentially suspends in aqueous dispersions on low-speed centrifugation (2000g), leaving the SWNTsin the sediment. In a surprising reversal, we now show that high-speed centrifugation (20000g) of well-dispersed preparations is effective in sedimenting carbon nanoparticles (CNP), while leaving the SWNTssuspended in aqueous media. Taken together, these two techniques allow the bulk scale (10 g) purificationof SWNTs by efficiently separating the two main contaminants, in an industrially viable process. We showthat the mechanism of these separations is based on the differential charging (
-potential) of the AC, CNPs,and SWNTs that comes about during the chemical processing. Due to their more robust structure, nitricacid oxidation leaves the CNPs with a surface charge density lower than that of the SWNTs, and thus theCNPs do not form stable dispersions in aqueous media during high-speed centrifugation. The efficiency ofthe process was confirmed by the high purification recovery factor (PRF = 90%), which is a measure ofthe fractional quantity of the product recovered after the purification. We demonstrate that the purity ofSWNTs significantly affects their mechanical and electrical properties.
-potential) of the AC, CNPs,and SWNTs that comes about during the chemical processing. Due to their more robust structure, nitricacid oxidation leaves the CNPs with a surface charge density lower than that of the SWNTs, and thus theCNPs do not form stable dispersions in aqueous media during high-speed centrifugation. The efficiency ofthe process was confirmed by the high purification recovery factor (PRF = 90%), which is a measure ofthe fractional quantity of the product recovered after the purification. We demonstrate that the purity ofSWNTs significantly affects their mechanical and electrical properties.