Analysis of Relaxation Behavior of Free Radicals in Irradiated Cellulose Using Pulse and Continuous-Wave Electron Spin Resonance

Kameya, Hiromi; Ukai, Mitsuko

doi:10.5772/51634

Cited by 4 publications

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References 26 publications

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“…). These lines are considered to be a triplet with a 30 G coupling constant arising from a C(5) carbon‐centered cellulose radical, although the central line of the triplet is superimposed with the strong central peak …”

Section: Resultsmentioning

confidence: 99%

“…These lines are considered to be a triplet with a 30 G coupling constant arising from a C(5) carbon-centered cellulose radical, although the central line of the triplet is superimposed with the strong central peak. 26 Figure 1(B) shows the ESR spectra of the same samples, but 120 days after irradiation, in the same scale. Not only is the intense central peak very similar for all samples (including the nonirradiated one), but mostly there is no evidence of the pair of lines upfield and downfield from the central line that is indicative of irradiation.…”

Section: Methods Validationmentioning

confidence: 99%

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Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition

et al. 2018

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confidence: 99%

Section: Methods Validationmentioning

confidence: 99%

Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition

et al. 2018

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“…The radical at the C(5) position in the glucose unit is comparably stable because of the nearby oxygen atom and alkyl group at the C(6) position. [30] Notably, the pathway of cellulose pyrolysis is still debated. Hosoya et al [31] and Mayes et al…”

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confidence: 99%

Quantitative Investigation of Free Radicals in Bio‐Oil and their Potential Role in Condensed‐Phase Polymerization

et al. 2015

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We report on the quantitative analysis of free radicals in bio-oils produced from pyrolysis of cellulose, organosolv lignin, and corn stover by EPR spectroscopy. Also, we investigated their potential role in condensed-phase polymerization. Bio-oils produced from lignin and cellulose show clear evidence of homolytic cleavage reactions during pyrolysis that produce free radicals. The concentration of free radicals in lignin bio-oil was 7.5×10(20) spin g(-1), which was 375 and 138 times higher than free-radical concentrations in bio-oil from cellulose and corn stover. Pyrolytic lignin had the highest concentration in free radicals, which could be a combination of carbon-centered (benzyl radicals) and oxygen-centered (phenoxy radicals) organic species because they are delocalized in a π system. Free-radical concentrations did not change during accelerated aging tests despite increases in molecular weight of bio-oils, suggesting that free radicals in condensed bio-oils are stable.

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“…Because levoglucosan and other light oxygenates, major pyrolysis products from cellulose, do not have unpaired electrons, the stable radical species in cellulose bio-oil could be located in the oligosaccharide moiety. The radical at the C(5) position in glucose unit is comparably stable because of the nearby oxygen and alkyl group at the C(6) position[42].…”

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Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance

Kim¹

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Partial oxidative pyrolysis of red oak was studied in a laboratory-scale, continuous fluidized bed reactor. The concentration of oxygen in sweep gas was between 0.525 % and 8.40 % (v/v), corresponding to equivalence ratios of 0.034 to 0.539. The influence of oxygen on the distribution and properties of pyrolysis products was investigated using various analytical methods, including GC-MS/FID, IC, HPLC and FT-IR. It was found that total biooil yield was not affected by varying oxygen concentration (61.2-64.8 g/100 g biomass) although the water content of the bio-oil increased. The elemental carbon content of bio-oil and biochar decreased with increasing oxygen concentration, being converted to noncondensable gases mainly CO and CO2. As expected, the presence of high concentration of oxygen in the sweep gas stream had detrimental effects on the pyrolysis products, including increase in water and oxygen content. However, the results also revealed that a small amount of oxygen in the sweep gas (0.525 to 1.05 %, v/v) improved the yield of hydrolyzable sugars and total yield of phenolic monomers. The bio-oil produced under oxidative pyrolysis also contained less acid and pyrolytic lignin. Oxygen increased the surface area of biochar. The results of this study suggest that carefully controlled partial oxidative pyrolysis can improve 16 the quality of bio-oil from fast pyrolysis, increasing the content of sugars and phenolic monomers.

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Analysis of Relaxation Behavior of Free Radicals in Irradiated Cellulose Using Pulse and Continuous-Wave Electron Spin Resonance

Cited by 4 publications

References 26 publications

Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition

Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition

Quantitative Investigation of Free Radicals in Bio‐Oil and their Potential Role in Condensed‐Phase Polymerization

Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance

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