Oxidative degradation of carbon blacks with nitric acid

Kamegawa, Katsumi; Nishikubo, Keiko; Kodama, Masaya; Adachi, Yoshio; Yoshida, Hisayoshi

doi:10.1016/s0008-6223(01)00310-4

Cited by 76 publications

(22 citation statements)

References 28 publications

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“…Traditional definitions of BC assume it to be insoluble in water, but this has been challenged, and BC is recognized to exist on a continuum of solubility. Recent studies have shown that BC can become soluble upon oxidation [63,64] and have detected dissolved forms of BC in aerosols [20] and aquatic dissolved OM [65]. The definitive study relating dissolved BC determined by chemical techniques to thermal optically-defined BC has not to our knowledge been performed.…”

Section: Biomass Burning Aerosolsmentioning

confidence: 99%

Detailed Source-Specific Molecular Composition of Ambient Aerosol Organic Matter Using Ultrahigh Resolution Mass Spectrometry and 1H NMR

2016

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Organic aerosols (OA) are universally regarded as an important component of the atmosphere that have far-ranging impacts on climate forcing and human health. Many of these impacts are related to OA molecular characteristics. Despite the acknowledged importance, current uncertainties related to the source apportionment of molecular properties and environmental impacts make it difficult to confidently predict the net impacts of OA. Here we evaluate the specific molecular compounds as well as bulk structural properties of total suspended particulates in ambient OA collected from key emission sources (marine, biomass burning, and urban) using ultrahigh resolution mass spectrometry (UHR-MS) and proton nuclear magnetic resonance spectroscopy ( 1 H NMR). UHR-MS and 1 H NMR show that OA within each source is structurally diverse, and the molecular characteristics are described in detail. Principal component analysis (PCA) revealed that (1) aromatic nitrogen species are distinguishing components for these biomass burning aerosols; (2) these urban aerosols are distinguished by having formulas with high O/C ratios and lesser aromatic and condensed aromatic formulas; and (3) these marine aerosols are distinguished by lipid-like compounds of likely marine biological origin. This study provides a unique qualitative approach for enhancing the chemical characterization of OA necessary for molecular source apportionment.

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Section: Biomass Burning Aerosolsmentioning

confidence: 99%

Detailed Source-Specific Molecular Composition of Ambient Aerosol Organic Matter Using Ultrahigh Resolution Mass Spectrometry and 1H NMR

2016

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“…This result suggests that the carbon black in the rubber is strongly attacked under the reaction conditions. Literature work 24 showed that carbon black can be easily oxidized by concentrated nitric acid to produce water soluble polyaromatic compounds. Therefore, these results suggest that treatment of the SBR with HNO 3 leads to the oxidation, not only of the polymeric material, but also of the carbon black, to produce a water soluble material.…”

Section: Resultsmentioning

confidence: 99%

“…The HNO 3 oxidation of carbonaceous materials is also well described in the literature. 24 Although, the mechanism and the location of these oxygenated groups are not clear, one can envisage that the oxidation might take place at different places in the carbon styrene butadiene polymer such as: the aromatic ring and at secondary or tertiary carbon of the main chain. In the case of oxidation at the aliphatic carbons the main polymeric chain will be broken, leading to the decrease of the polymer molecular weight.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Rios

Gontijo

Ferraz

et al. 2006

J. Braz. Chem. Soc.

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Neste trabalho é descrita a desvulcanização da borracha SBR (Styrene Butadiene Rubber) via oxidação controlada com ácido nítrico. Análises por IV, RMN de 1 H e 13 C, CHN, TG, GPC e experimentos de DTP-EM (Decomposição a Temperatura Programada -Espectrometria de Massas) sugerem que o ácido nítrico promove dois processos: (i) a desvulcanização por oxidação das pontes de enxofre e (ii) a oxidação da cadeia carbônica levando à formação de grupos -COOH e -NO 2 . Em condições mais drásticas de reação, a cadeia polimérica é fortemente oxidada e se fragmenta formando uma fração altamente oxigenada, de baixo peso molecular e solúvel em água.This work describes the devulcanization of vulcanized SBR (Styrene Butadiene Rubber) based on controlled oxidation with nitric acid. IR, 1 H and 13 C-NMR, CHN elemental analyses, TG, GPC and TPD-MS (Temperature Programmed Decomposition-Mass Spectrometry) experiments suggest that nitric acid promotes two processes: (i) devulcanization by oxidation of the sulfide crosslinks and (ii) oxidation of the carbon framework leading to the formation of -COOH and -NO 2 groups. Under aggressive conditions (HNO 3, reflux) the polymer chain is strongly oxidized and fragmented to a highly oxygenated low molecular weight fraction, which is soluble in water. Keywords: devulcanization, HNO 3 , oxidation IntroductionThe disposal and reuse of waste tires remain not only a serious environmental concern but also an economical issue. Several alternatives, such as direct uses of scrap tires, combustion to produce energy, pyrolysis to produce fuels, the use of crumbles to asphalt roads and devulcanization to recycle the polymer have been extensively investigated in the last decades. Different chemical, physical and biological processes for the devulcanization of vulcanized rubber have been reported in the literature. 1 For the chemical devulcanization processes an extensive variety of agents such as: sulphides, e.g. diphenyl-disulphides, mercaptans, thiophenol, phosphorus compounds, e.g. triphenylphosphine and dibutylphosphite have been used. 2-13 Also, some reducing compounds have been studied for the devulcanization process, such as lithium aluminum hydride, 14 phenyl lithium, 15 CuCl/Bu 3 N, 16 alkaline metals (e.g. Na o ) and FeCl 2 / hydrazine. 17 On the other hand, oxidative processes for the devulcanization have been scarcely investigated. One example is the use of CHCl 3 /O 3 /H 2 O 2 , which showed low efficiency and high cost. 18 Nitric acid, HNO 3 , is a strong oxidizing agent which is well known to react with all types of sulfur groups, 19 offering the possibility to devulcanize rubber by oxidizing the sulfide crosslinks. The corrosion effect of nitric acid on rubber surface has been observed in 1985 by scanning electron microscopy. 20 Also HNO 3 and 30% H 2 O 2 have been used for the modification of the surface properties of rubber powder used as filler. 21 However, the use of the controlled oxidation with HNO 3 to devulcanize vulcanized rubbers has not yet been studied.In this work a detailed inv...

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“…An advantage of the adopted selected oxidative treatment, is that it provides the partial demolition of the CB microstructure and the functionalization at the edge of the basal planes of the graphitic layers [62], and not on them. Inside water suspension, GL layers are made by small flat nanoparticles decorated at the edge with oxygen functional groups (mainly carboxylic/carbonylic and hydrazones), and the graphenic basal planes are untouched [63].…”

Section: Experimental and Discussionmentioning

confidence: 99%

Graphene-Like Layers from Unconventional Carbon Sources: New Perspectives on Hybrid Materials and π-system Synergisms

Capua

Gargiulo

AlfГЁ

2016

Eurasian Chem. Tech. J.

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We developed a new approach for producing graphene-like (GL) materials through a two-steps oxidation/reduction method starting from a nanostructured (high surface) carbon black, a versatile carbonaceous material prone to be structurally and chemically modified in quite mild wet conditions. Atomic Force Microscopy and zetapotential measurements allowed to model the assembling mechanisms and the role of hydrophobic interactions, demonstrating the possibility to easily tune the surface morphology. GL materials have been then employed in a large variety of hybrid materials for innovative applications, and characterized by chemical, electrical, structural and spectroscopic techniques. With Metal-Organic Frameworks, GL produced conducting composites with electrical conductivity tunable by changing the concentration of the parent materials; Eumelanin/GL and TiO 2 -nanoparticles/GL were also studied for photocatalysis and biosensors applications.

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Oxidative degradation of carbon blacks with nitric acid

Cited by 76 publications

References 28 publications

Detailed Source-Specific Molecular Composition of Ambient Aerosol Organic Matter Using Ultrahigh Resolution Mass Spectrometry and 1H NMR

Detailed Source-Specific Molecular Composition of Ambient Aerosol Organic Matter Using Ultrahigh Resolution Mass Spectrometry and 1H NMR

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Graphene-Like Layers from Unconventional Carbon Sources: New Perspectives on Hybrid Materials and π-system Synergisms

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