Determination of traces of elemental impurities in single walled (SWNT) and multi walled (MWNT) pristine and purified carbon nanotubes by instrumental neutron activation analysis

Braun, Tibor; Rausch, H.; Biró, László Péter; Kiricsi, Imre

doi:10.1023/b:jrnc.0000040850.79232.71

Cited by 13 publications

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“…Among the available analytical tools, NAA is the most advanced and accurate tool for determining metals at low concentrations, is highly sensitive, and requires no sample preparation. Ge et al . used ICP‐MS to analyze metal impurities in CNTs with high detection sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

et al. 2015

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Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red–orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO4/HNO3 and H2SO4/HNO3 mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs.

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Section: Introductionmentioning

confidence: 99%

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

et al. 2015

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“…6, 2011 During the synthesis of CNTs, generally by chemical vapor deposition, arc discharge or laser ablation, it is necessary the use of metallic catalysts and the most common ones are based on nickel, cobalt, iron, lanthanum or their combinations. 2,8,9 In general, commercial carbon nanotubes must be submitted to a final processing step for the removal of amorphous carbon, residues of metallic catalysts and side products 10 by chemical and physical methods. 11,12 However, even after an acid washing step (the most common method for CNTs purification, e.g., 36 h at 80 °C using HNO 3 ), metals are still present in relatively high levels because a significant part of them is sheathed by several graphite layers inside the CNTs structure.…”

Section: Introductionmentioning

confidence: 99%

“…In this way, the development of methods for the determination of metallic elements in low concentration is strongly required for CNTs. 10,11 The most common way of sample introduction using atomic spectrometric techniques is as aqueous solutions. However, the main problem concerning the determination of impurities in CNTs is the sample preparation step since these materials are extremely difficult to bring into solution in view of their stable structure.…”

Section: Introductionmentioning

confidence: 99%

“…On this aspect, NAA is one of the most powerful techniques for direct analysis of solid samples and it has been proposed for determination of trace elemental impurities in SWCNT and MWCNT. 10 However, despite some advantages as high sensitivity and selectivity for many elements it requires a nuclear reactor that makes difficult its use for routine analysis. 23 On the other hand, the direct analysis of solid samples has been proposed as an alternative in atomic absorption spectrometry.…”

Section: Introductionmentioning

confidence: 99%

“…Other elements, such as Al, Cu, Co and Mg, were found in mg kg -1 levels in some samples and, depending on the industrial application, they can affect the properties of the final materials. 9,10,12 In Table 5 it is possible to see that DSS-ET AAS allowed LODs ranging from 2 to 200 times lower than the values obtained with digestion methods even using ICP-MS which is generally considered as a powerful technique for the determination of trace elements. Values for LOD were calculated for the maximum applicable sample mass for each method that was 7, 50 and 200 mg for DSS-ET AAS, microwave-assisted wet digestion and MIC, respectively.…”

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Determination of metal impurities in carbon nanotubes by direct solid sampling electrothermal atomic absorption spectrometry

Mello¹,

Rodrigues²,

Nunes³

et al. 2011

J. Braz. Chem. Soc.

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soluções aquosas e massa máxima de amostra. Para comparação dos resultados as amostras foram analisadas por espectrometria de massa com plasma indutivamente acoplado (ICP-MS) e espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) após decomposição por via úmida em sistema de alta pressão assistida por micro-ondas e também por combustão iniciada por micro-ondas. Não foram observadas diferenças significativas entre os resultados obtidos pelo método proposto e pelas outras técnicas. A exatidão também foi avaliada por comparação com resultados de análise por ativação neutrônica (NAA). A calibração foi possível com soluções de referência aquosas. Os sinais de fundo foram sempre inferiores a 0,02 (altura de pico) e o uso de modificador químico não foi necessário. O método proposto possibilitou a determinação de todos os analitos, com menores limites de detecção quando comparados com as outras técnicas.Metal impurities (Al, Cd, Co, Cr, Cu, Mg, Mn and Pb) were determined in carbon nanotubes (CNTs) by direct solid sampling electrothermal atomic absorption spectrometry (DSS-ET AAS, deuterium lamp background corrector). Parameters as pyrolysis and atomization temperatures, use of Pd as chemical modifier, feasibility of calibration using aqueous standard solutions and maximum sample mass were investigated. Results obtained by the proposed method were compared with those obtained by neutron activation analysis (NAA) and also by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES) after high-pressure microwave assisted wet digestion and microwave-induced combustion methods. No significant differences were observed between the results obtained by DSS-ET AAS, ICP-MS and ICP OES after both digestion methods and also by NAA. Calibration was performed using aqueous standards. Background signals were always lower than 0.02 (peak height) and no chemical modifier was used. The proposed method allowed the determination of all elements in CNTs with lower limits of detection in comparison with other techniques.Keywords: carbon nanotubes, metal impurities, solid sampling, electrothermal atomic absorption spectrometry IntroductionSince the advent of nanotechnology the development of new materials with a wide range of special properties has been performed for very different applications in almost all technological fields. With the discovery of carbon nanotubes (CNTs) by Iijima, 1 this new class of nanomaterials provided unique chemical, mechanical and electronic properties. In recent years, carbon nanotubes have received a growing interest in several fields as materials industry, electronics, medicine and also in analytical applications. [2][3][4][5][6][7] Carbon nanotubes can be described as a kind of graphite structure which is based on benzene-type hexagonal rings of carbon atoms, rolled up in a nanoscale tube (diameter ranging from a few tenths to tens of nanometers). This nanomaterial can be defined as a single-wall carbon nanotube (SWCNT) ...

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Multi-Walled Carbon Nanotubes

Kukovecz

Kozma

2013

Springer Handbook of Nanomaterials

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a b s t r a c tThermal conductivity of individual multiwalled carbon nanotubes (MWCNT) is measured using a pulsed photothermal reflectance technique. Intrinsic thermal conductivity of individual MWCNT with a diameter 150 nm and length 2 mm at room temperature is extracted to be 2586 W/mK. Individual MWCNT is surrounded by SiO 2 , so parallel resistor model is applied in which SiO 2 supportive is treated as a conducting channel that transports heat in parallel with MWCNT.

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Determination of traces of elemental impurities in single walled (SWNT) and multi walled (MWNT) pristine and purified carbon nanotubes by instrumental neutron activation analysis

Cited by 13 publications

References 11 publications

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

Determination of metal impurities in carbon nanotubes by direct solid sampling electrothermal atomic absorption spectrometry

Multi-Walled Carbon Nanotubes

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