Purification of single-wall carbon nanotubes by ultrasonically assisted filtration

Shelimov, Konstantin B.; Esenaliev, Rinat O.; Rinzler, Andrew G.; Huffman, Chad; Smalley, R. E.

doi:10.1016/s0009-2614(97)01265-7

Cited by 351 publications

(189 citation statements)

References 20 publications

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“…The adsorption data show the potential for CNTs to adsorb significant quantities of divalent cations, especially on carboxylic functional groups, while panel (c) shows that insufficient water washing can lead to detectable residual bioavailable Ni. Because nanotubes are often treated with oxidizing acids such as HNO 3 or H 2 SO 4 , carboxylic and other oxygen-containing functional groups are expected to be common at this stage of processing. Figure 7 provides evidence for the third mechanism -that oxidation during or after acid dissolution can attack carbon shells and expose fresh metal without sufficient time for its removal by etching.…”

Section: 12mentioning

confidence: 99%

“…Many commercial carbon nanotube samples have been post-processed to reduce metal and/or amorphous carbon, and to increase the nanotube fraction, but even these "purified" samples typically contain significant quantities (1.2-14.3%) of residual metal [1,2]. Nanotube purification technologies continue to improve [3][4][5][6][7][8][9], but deep purification can damage tube structure [10][11][12] and for the foreseeable future, most CNT samples will contain metals.…”

Section: Introductionmentioning

confidence: 99%

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Targeted removal of bioavailable metal as a detoxification strategy for carbon nanotubes

Liu

Guo

Morris

et al. 2008

Carbon

124

110

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There is substantial evidence for toxicity and/or carcinogenicity upon inhalation of pure transition metals in fine particulate form. Carbon nanotube catalyst residues may trigger similar metal-mediated toxicity, but only if the metal is bioavailable and not fully encapsulated within fluid-protective carbon shells. Recent studies have documented the presence of bioavailable iron and nickel in a variety of commercial as-produced and vendor "purified" nanotubes, and the present article examines techniques to avoid or remove this bioavailable metal. First, data are presented on the mechanisms potentially responsible for free metal in "purified" samples, including kinetic limitations during metal dissolution, the re-deposition or adsorption of metal on nanotube outer surfaces, and carbon shell damage during last-step oxidation or one-pot purification. Optimized acid treatment protocols are presented for targeting the free metal, considering the effects of acid strength, composition, time, and conditions for post-treatment water washing. Finally, after optimized acid treatment, it is shown that the remaining, non-bioavailable (encapsulated) metal persists in a stable and biologically unavailable form up to two months in an in vitro biopersistence assay, suggesting that simple removal of bioavailable (free) metal is a promising strategy for reducing nanotube health risks.

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Section: 12mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Targeted removal of bioavailable metal as a detoxification strategy for carbon nanotubes

Liu

Guo

Morris

et al. 2008

Carbon

124

110

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“…Konstantin et al 19 developed an ultrasonically assisted filtration method which allows the purity of nanotubes to reach >90%. Highly pure and length-selected SWNTs in aqueous solution can be obtained by column chromatography, according to Duesberg et al 20 Limited solubility of nanotubes is the major disadvantage of sizeexclusion chromatographic methods.…”

Section: Introductionmentioning

confidence: 99%

Purification and Characterization of Single-Wall Carbon Nanotubes (SWNTs) Obtained from the Gas-Phase Decomposition of CO (HiPco Process)

et al. 2001

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A purification method has been developed that provides for the removal of metal catalysts and impurity carbon from laser-oven-grown single-wall carbon nanotube (SWNT) material. The oxidation rate of SWNTs in air at elevated temperatures is correlated to the metal content of the sample. Sample purity is documented with SEM, TEM, electron microprobe analysis, Raman, and UV-vis-near-IR. We also note that the relative intensity of the electronic transitions in the near-infrared to the continuum absorption at 400 nm in the UV serves as a useful monitor of the perturbation of the sidewall π-electron density of SWNTs due to sidewall substitution and/or oxidation.

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“…Shelimov et al [45] used ultrasonically assisted microfiltration for purifying SWNTs from amorphous and crystalline carbon impurities and metal particles. SWNTs with more than 90% purity were generated by this process.…”

Section: Purificationmentioning

confidence: 99%

Carbon Nanotubes for Biomedical Applications

2011

Carbon Nanostructures

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Abstract-Carbon nanotubes (CNTs) have many unique physical, mechanical, and electronic properties. These distinct properties may be exploited such that they can be used for numerous applications ranging from sensors and actuators to composites. As a result, in a very short duration, CNTs appear to have drawn the attention of both the industry and the academia. However, there are certain challenges that need proper attention before the CNTbased devices can be realized on a large scale in the commercial market. In this paper, we report the use of CNTs for biomedical applications. The paper describes the distinct physical, electronic, and mechanical properties of nanotubes. The basics of synthesis and purification of CNTs are also reviewed. The challenges associated with CNTs, which remain to be fully addressed for their maximum utilization for biomedical applications, are discussed.

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Purification of single-wall carbon nanotubes by ultrasonically assisted filtration

Cited by 351 publications

References 20 publications

Targeted removal of bioavailable metal as a detoxification strategy for carbon nanotubes

Targeted removal of bioavailable metal as a detoxification strategy for carbon nanotubes

Purification and Characterization of Single-Wall Carbon Nanotubes (SWNTs) Obtained from the Gas-Phase Decomposition of CO (HiPco Process)

Carbon Nanotubes for Biomedical Applications

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