Nitric acid oxidation of carbon fibers and the effects of subsequent treatment in refluxing aqueous NaOH

Wu, Zhihong; Pittman, Charles U.; Gardner, Steven D.

doi:10.1016/0008-6223(95)00145-4

Cited by 240 publications

(117 citation statements)

References 23 publications

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“…New features appeared at 405.5 eV and 399.6 eV. The new N-species at 405.5 eV can be assigned to -NO 2 functionalities and are only found after HNO 3 oxidation [45]. The broad band at 398.8 eV related to C-N species is believed to be pyridine-like rings near graphitic structures [46].…”

Section: Surface Composition Of Carbon Fibresmentioning

confidence: 94%

Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion

Tran

Kalinka

et al. 2008

Composites Science and Technology

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Section: Surface Composition Of Carbon Fibresmentioning

confidence: 94%

Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion

Tran

Kalinka

et al. 2008

Composites Science and Technology

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“…Rourke et al [31] reported that GO directly obtained after the oxidation of a graphitic material exhibits a more complex structure consisting of two main entities: functionalized graphene-like sheets and oxidized debris (OD) strongly adhered to these flat entities. This assumption is based on results obtained using carbon nanotubes [32,33] or carbon fibers [34] as parent graphitic materials. OD consist of large poly-aromatic molecules with high amount of oxygen groups anchored to the edges, that also act as a surfactant able to disperse clean GO sheets.…”

Section: Introductionmentioning

confidence: 99%

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Rodriguez-Pastor

Ramos-Fernández

Varela-Rizo

et al. 2015

Carbon

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Please cite this article as: Rodriguez-Pastor, I., Ramos-Fernandez, G., Varela-Rizo, H., Terrones, M., Martin-Gullon, I., Towards the understanding of the graphene oxide structure: How to control the formation of humic-and fulviclike oxidized debris, Carbon (2014), doi: http://dx.doi.org/10.1016/j.carbon. 2014.12.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract Former structural models of graphene oxide (GO) indicated that it consists of graphenelike sheets with oxygen groups, and no attention was paid to the resulting sheet size. We now provide evidence of the complex GO structure consisting of large and small GO sheets (or oxidized debris). Different oxidation reactions were studied. KMnO 4 derived GO consists of large sheets (20-30 wt. %), and oxidized debris deposits, which are formed by humic-and fulvic-like fragments. Large GO sheets contain oxygen groups, especially at the edges, such as carbonyl, lactone and carboxylic groups. Humic-like debris consists of an amorphous gel containing more oxygenated groups and trapped water molecules. The main desorbable fraction upon heating is the fulvic-like material, which contains oxygen groups and fragments with high edge/surface ratio. KClO 3 in HNO 3 or the Brodie method produces a highly oxidized material but at the flake level surface only; little oxidized debris and water contents are found. It is noteworthy that an efficient basal cutting of the graphitic planes in addition to an effective intercalation is caused by KMnO 4 , and the aid of NaNO 3 makes this process even more effective, thus yielding large monolayers of GO and a large amount of humic-and fulvic-like substances.

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“…Washing with NaOH solutions effectively dissolves the soluble residues generated during oxidation; however, Na + ions cannot be completely eliminated during the thermal treatment and can remain in the micropores. 17 In contrast, the use of NH 4 OH under reflux ensures that only H + and OH -ions occupy the surface acidic and basic sites after rinsing with water and drying at 100 °C.…”

Section: Introductionmentioning

confidence: 99%

Characterization of copper adsorption on oxidized activated carbon

Mesquita¹,

Martelli²,

Gorgulho³

2006

J. Braz. Chem. Soc.

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Esse artigo discute a adsorção de íon Cu(II) em carvão ativado oxidado com HNO 3 . As modificações introduzidas na superfície do carvão ativado (CA) foram caracterizadas por medidas de área superficial, espectroscopia de absorção no infravermelho, titulação pelo tradicional método de Boehm e titulação potenciométrica. Os dados da titulação potenciométrica foram ajustados através de um método não linear desenvolvido para determinar a concentração e distribuição do pKa dos sítios ácidos ionizáveis presentes na superfície do CA, antes e após a oxidação com HNO 3 . Os estudos de adsorção foram realizados em batelada para a faixa de concentração de 0,08 a 1,75 mmol L -1 em pH = 4,0. Os resultados mostraram que o tratamento do CA com ácido leva à diminuição na área superficial aparente e produz leves modificações na estrutura de poros. Entretanto, a oxidação influenciou fortemente a estrutura química da superfície do CA através do aumento na concentração de grupos ácidos com pKa < 6, causando assim uma melhora significativa na adsorção do íon Cu(II). A maior capacidade de adsorção do CA oxidado foi relacionada à presença de grupos ácidos com pKa < 4, revelando o importante papel destes grupos na adsorção pelo mecanismo de troca iônica. This paper discusses Cu(II) ion adsorption onto oxidized activated carbon with HNO 3 . The modifications introduced on the activated carbon (AC) surface were characterized by surface area measurement, FT-IR spectroscopy, titration by the traditional Boehm procedure, and potentiometric titration. A nonlinear method for fitting acid-base potentiometric titration data was applied to determine the concentration and pKa distributions of the ionizable acidic sites on AC, before and after HNO 3 oxidation. Adsorption studies were conducted in batch mode for the concentration range 0.08 to 1.75 mmol L -1 and pH = 4.0. Results showed that the acid treatment of AC leads to a decrease in apparent surface areas and produces slight modifications in pore structure. However, oxidation strongly influenced the AC surface chemical structures by increasing the concentration of acidic groups with pKa < 6.0, which significantly improved Cu(II) ion adsorption. The uptake enhanced for oxidized carbon was related to the presence of acidic groups with pKa lower than 4, revealing the important role of acidic groups in adsorption by ion-exchange mechanisms.

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Nitric acid oxidation of carbon fibers and the effects of subsequent treatment in refluxing aqueous NaOH

Cited by 240 publications

References 23 publications

Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion

Carbon fibre reinforced poly(vinylidene fluoride): Impact of matrix modification on fibre/polymer adhesion

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Characterization of copper adsorption on oxidized activated carbon

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