Co-synthesis, purification and characterization of single- and multi-walled carbon nanotubes using the electric arc method

Mathur, R.B.; Seth, Sarita; Lal, C.; Rao, Rahul; Singh, Bhanu Pratap; Dhami, T.L.; Rao, Apparao M.

doi:10.1016/j.carbon.2006.07.027

Cited by 79 publications

(43 citation statements)

References 39 publications

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“…The different structural forms of carbon exhibit different reactivity towards oxidation. In general the purified tubes break down at a higher temperature than the amorphous carbon which can be seen by the higher weight loss onset temperature for the purified sample (350-400 • C), consistent with previous reports [13,32,33]. The corresponding most rapid weight loss observed in the DTG curve for the purified sample (Fig.…”

Section: -P5supporting

confidence: 91%

Purification of single-walled carbon nanotubes

Yaya

Ewels

Wagner

et al. 2011

Eur. Phys. J. Appl. Phys.

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Abstract. We present a study of purification of single-walled carbon nanotubes (SWCNTs) using different oxidation temperatures and chemical treatments. We have developed a simple two annealing-steps procedure resulting in high nanotube purity with minimal sample loss. The process involves annealing the SWCNTs at 300 • C for 2 h with subsequent reflux in 6 M HCl at 130 • C, followed by further annealing at 350 • C for 1 h with reflux in 6 M HCl at 130 • C. The process results in effective removal of carbon impurities and metal particles which are associated with SWCNTs production. The process is less time consuming (complete in 4.5 h) than conventional acid purification methods which require over 5 h, and less destructive than conventional methods with a yield of 26%. SWCNT purity was assessed using Raman spectroscopy, thermogravimetry and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.

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Section: -P5supporting

confidence: 91%

Purification of single-walled carbon nanotubes

Yaya

Ewels

Wagner

et al. 2011

Eur. Phys. J. Appl. Phys.

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“…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%

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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“…The residue on the filter paper was washed with distilled water (4-5 times) to remove the acid. The residue was dried in an oven at 80 C-100 C for 5 h. After that, the nanocarbons were weighted and kept in desiccators [13]. The products were observed by using scanning electron microscopy (SEM) to analyse the samples.…”

Section: Purificationmentioning

confidence: 99%

Voltage effects on the production of nanocarbons by a unique arc-discharge set-up in solution

Jahanshahi

Raoof

Seresht

2009

Journal of Experimental Nanoscience

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Well graphitised nanocarbons including onion-like fullerenes and single-and multi-walled carbon nanotubes (CNTs) were synthesised in high yield by automatic arc-discharge method in solution. This technique is considered a low-cost method since it does not require any expensive equipment. Herein, an arc discharge full automatic set-up was used for fabrication of CNTs which enables controlling of the gap between the two electrodes and the voltage as well. Carbon nanostructures under a controlled amount of voltage (from 10 to 30 V) were synthesised where Ni : Mo as a catalyst and LiCl 0.25 M as a solution were used. Subsequently, a modified acid treatment method was applied as purification stage of the products. The production rate of CNTs was as high as 7.7 mg min À1 while the voltage was set at 30 V. Scanning electron microscopy and transmission electron microscopy as well as Raman spectroscopy were employed to study the morphology of these carbon nanostructures. The results indicated that CNTs synthesised at a voltage of 30 V had the best quality and elongated straight structures. The mechanism of the voltage conditions for preparing nanocarbons as well as their characterisation are discussed.

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Co-synthesis, purification and characterization of single- and multi-walled carbon nanotubes using the electric arc method

Cited by 79 publications

References 39 publications

Purification of single-walled carbon nanotubes

Purification of single-walled carbon nanotubes

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

Voltage effects on the production of nanocarbons by a unique arc-discharge set-up in solution

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