Effect of hydroxyl radical on the structure of multi-walled carbon nanotubes

Li, Wei; Bai, Ying; Zhang, Yanke; Sun, Mingli; Cheng, Rongming; Xu, Xuecheng; Chen, Yiwei; Mo, Yujun

doi:10.1016/j.synthmet.2005.07.346

Cited by 115 publications

(84 citation statements)

References 52 publications

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“…TRANSFORMATION Petersen et al (2011) provided an overview of possible transformation reactions, which, in the absence of environmental MWCNT studies, was mostly based on chemistry and chemical engineering studies. Fullerene-like end caps and defects on MWCNT side walls are supposed to be susceptible for oxidation (Niyogi et al, 2002;Li et al, 2005), where smaller MWCNT diameters are associated with a higher reactivity. Chemical oxidation requires strong oxidative forces, unlikely to occur in the environment, yet photooxidation is possible.…”

Section: Transport Pathways From the Product To The Aquatic Systemsmentioning

confidence: 99%

A Review of the Properties and Processes Determining the Fate of Engineered Nanomaterials in the Aquatic Environment

Peijnenburg

Baalousha

Chen

et al. 2015

Critical Reviews in Environmental Science and Technology

177

103

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Section: Transport Pathways From the Product To The Aquatic Systemsmentioning

confidence: 99%

A Review of the Properties and Processes Determining the Fate of Engineered Nanomaterials in the Aquatic Environment

Peijnenburg

Baalousha

Chen

et al. 2015

Critical Reviews in Environmental Science and Technology

177

103

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“…Sham [31] reported surface functionalities of CNTs via UV/O 3 combined treatment. In this paper, we firstly make an attempt to use the combination of ultraviolet (UV) and Fenton oxidation process for oxidation etching treatment of multi-walled carbon nanotubes (MWNTs), assuming that UV-assisted Fenton oxidation process (UV/Fenton) should result in better etching rates and efficiencies compared to individual Fenton oxidation processes investigated in our previous work [32] . This assumption relies mainly on 1) AOPs work according to the principle of generation of free radicals and the subsequent attack on the surface of MWNTs; 2) the efficacy of AOPs depends strongly on both the rate of generation of the free radicals and the extent of contact between the radicals and the reactive species; 3) UV irradiation improves the rate of generation of free radicals during UV/Fenton oxidation process; and 4) the synergetic effect (or combined effect) between the methods is advantageous to minimize or eliminate the drawbacks of individual methods [25] .…”

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confidence: 99%

Efficient photo-assisted Fenton oxidation treatment of multi-walled carbon nanotubes

Fan

Wei

et al. 2007

CHINESE SCI BULL

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In this paper, a new and efficient way to oxidize and functionalize the multi-walled carbon nanotubes (MWNTs) has been developed by using a combination of ultraviolet (UV) irradiation and Fenton oxidation process, namely UV/Fenton oxidation treatment. Comparing with conventionally individual Fenton oxidation treatment of MWNTs, UV/Fenton combined treatment improved the etching rates and efficiencies and hence reduced the time for surface modification of MWNTs, which was proved to be an effective method in etching and functionalizing CNTs. The formation of new functional groups, structural changes and thermal stability during oxidation period were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and could be clarified by thermogravimetric analysis (TGA), which showed that it was under UV irradiation conditions that MWNTs could be rapidly functionalized with hydroxyl, carbonyl and carboxyl groups in the presence of Fenton reagents, originating from the increase in the gross HO• concentration and the existent synergetic effect when using UV irradiation combing with Fenton oxidation process. Introduction of such new oxygen-containing functional groups was attributed to attacks of HO• on defect sites and unsaturated bonds of C=C in the MWNTs sample, which should play an important role in accounting for the FTIR and Raman spectral changes.multi-walled carbon nanotubes (MWNTs), functionalization, UV/Fenton combined oxidation treatment As a consequence of their superior physicochemical properties and large potential applications, carbon nanotubes (CNTs) have opened new frontiers in the field of nanotechnology and nanoscience [1][2][3] . However, graphite and similar graphene including CNTs are well known to be chemically quite inert and insoluble in most organic and aqueous solvents, which limit their solution-based manipulation and processability, greatly hindering their wide application in practical work. So recently the modification or functionalization of CNTs has attracted great attention, primarily to improve their solubility and dispersibility in various solvents especially in aqueous solutions. Several ways of dispersion and solubilization have been explored and can be roughly divided into two approaches. One is noncovalent functionalization of CNTs with surfactants, polymers and biological macromolecules, where the mechanism of dispersion is based on adsorption, wrapping, π-stacking and hydrophobic/ π-π interactions [4][5][6][7][8][9] ; the other to render CNTs soluble and dispersible is convalent attachment of organic functional groups, which can be referred to as convalent functionalization. Two main strategies are currently used to attach functional groups onto CNTs. In the first case, the required functional groups are attached directly onto CNTs by using 1,3-dipolar cycloaddition, Birch reduction, and reactions with nitrenes, radicals and carbenes, etc. [10][11][12][13][14] . In the second one, a simple bridgehead func-

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“…5). For the uncut MWCNTs, the main peak (284.6 eV) was attributed to C-C 1 s corresponding to the graphitic carbon, while the small peak at 286.0 eV was attributed to C-OH [13]. Because the purified MWCNTs have a few structural defects, a portion reacted with the water in the air, which introduced some hydroxyl groups on the sidewalls.…”

Section: Resultsmentioning

confidence: 99%