Radical yields in the radiolysis of cyclic compounds

LaVerne, Jay A.; Enomoto, Kazuyuki; Araos, M. S.

doi:10.1016/j.radphyschem.2007.02.017

Cited by 7 publications

(7 citation statements)

References 10 publications

(10 reference statements)

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“…50 Finally, the H 2 yields show no dependence on the addition of the excited state scavengers anthracene and biphenyl in the radiolysis of pyridine and aniline. 47,51 The formation of H 2 in the γ-radiolysis of aniline is not affected by the addition of naphthalene and TMPD either. 51 Apparently, none of the conventional quenchers are capable of scavenging any appreciable fraction of H 2 formed in the radiolysis of liquid aromatics.…”

Section: ' Results and Discussionmentioning

confidence: 98%

“…One might assume that biphenyl is formed by the recombination of phenyl radicals by analogy to the dimer formation in the radiolysis of cyclic alkanes. 47 However, aromatic compounds are good radical scavengers, and studies with I 2 have shown that both C 6 H 5 • and the H• atom combine with parent benzene molecules to initiate formation of phenylcyclohexadienyl and cyclohexadienyl radicals, respectively. 7 Subsequent reactions of the phenylcyclohexadienyl radical result in biphenyl formation, but most radicals generated in radiolysis contribute to polymer production.…”

Section: ' Results and Discussionmentioning

confidence: 99%

“…Experimental efforts to elucidate the precursor of H 2 produced in the radiolysis of liquid aromatics have used quenchers to selectively scavenge radicals, electrons, radical cations or excited states. The addition of typical radical scavengers, like iodine, shows no effect on the formation of H 2 in the radiolysis of benzene, pyridine, and toluene . Unfortunately, radical scavengers I 2 and 1,1-diphenyl-2-picrylhydrazyl (DPPH) cannot be used with aniline because of their direct chemical interaction .…”

Section: Resultsmentioning

confidence: 99%

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Role of the Low-Energy Excited States in the Radiolysis of Aromatic Liquids

2011

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The contribution of the low-energy excited states to the overall product formation in the radiolysis of simple aromatic liquids--benzene, pyridine, toluene, and aniline--has been examined by comparison of product yields obtained in UV-photolysis and in γ-radiolysis. In photolysis, these electronic excited states were selectively populated using UV-light excitation sources with various energies. Yields of molecular hydrogen and of "dimers" (biphenyl, bibenzyl, dipyridyl for benzene, toluene, pyridine, respectively, and of ammonia and diphenylamine for aniline) have been determined, since they are the most abundant radiolytic products. Negligibly small production of molecular hydrogen in the UV-photolysis of aromatic liquids with excitation to energies of 4.88, 5.41, 5.79, and 6.70 eV and the lack of a scavenger effect suggest that this product originates from short-lived high-energy singlet states. A significant reduction in "dimer" radiation-chemical yields in the presence of scavengers such as anthracene or naphthalene indicates that the triplet excited states are important precursors to these products. The results for toluene and aniline suggest that efficient dissociation from the lowest-energy excited triplet state leads to noticeable "dimer" production. For benzene and pyridine, the lowest-energy triplet excited states are not likely to fragment into radicals because of the relatively large energy gap between the excited state level and corresponding bond dissociation energy. The "dimer" formation in the radiolysis of benzene and pyridine is likely to involve short-lived high-energy triplet states.

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Section: ' Results and Discussionmentioning

confidence: 98%

Section: ' Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Role of the Low-Energy Excited States in the Radiolysis of Aromatic Liquids

2011

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“…It is well known that polymers containing aliphatic structure are sensible to radiations [14,15] but there are no systematic studies on the radiation induced effects in aliphatic polyesters containing cyclohexylene rings. The ionizing radiation effects on cyclic compounds lead to carbon-hydrogen bond breakage and, in the case of cyclohexane, the resulting molecular radicals disproportionate and the H atom mainly combines or undergoes H abstraction [16,17].…”

Section: Introductionmentioning

confidence: 99%

Effect of Gamma Irradiation on Fully Aliphatic Poly(Propylene/Neopentyl Cyclohexanedicarboxylate) Random Copolymers

et al. 2018

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The widespread use of conventional petrochemical-based plastics and their low biodegradability led to a growing pollution issue. Among the class of the aliphatic polyesters, poly(propylene/neopentyl cyclohexanedicarboxylate) [P(PCExNCEy)] random copolymers combine promising physical-chemical properties and biodegradability features but they are characterized by slow degradability. The effect of gamma radiation on both chemical-physical properties and compostability was evaluated by several techniques on different samples irradiated in air at absorbed doses up to 500 kGy and in water or under oxidative atmosphere up to 100 kGy. According to the results obtained, exposure to radiation significantly affects polymer molecular weight and hydrophilicity, while crystallinity remains unaltered and biodegradability is only slightly influenced. In particular, among the different irradiation environments used, irradiation in water seems to favor the polymer degradation in compost.

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“…Systems such as UV-hydrogen peroxide (Aleboyeh et al, 2005;Baldrian et al, 2006), ozonation (Farré et al, 2005;Liu et al, 2007) and photo-Fenton (Ruppert et al, 1993) have been extensively described in literature and have demonstrated their efficiency. More recently, techniques such as photocatalysis (Ollis, 2000), sonolysis (Drijvers et al, 1999;Minero et al, 2008) and c-radiolysis (Getoff, 1996;LaVerne et al, 2007) have shown promising prospects. Solar photocatalysis is especially attractive as it is based on a fully renewable and cheap energy source (Malato et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic and combined anaerobic–photocatalytic treatment of textile dyes

et al. 2008

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A photocatalytic process based on immobilized titanium dioxide was used to treat crude solutions of azo, anthraquinone and phthalocyanine textile dyes. In addition, the process was applied to the treat autoxidized chemically reduced azo dyes, i.e. representatives of recalcitrant dye residues after biological sequential anaerobic-aerobic treatment. Photocatalysis was able to remove more than 90% color from crude as well as autoxidized chemically reduced dye solutions. UV-absorbance and COD were also removed but to a lower extent (50% in average). The end products of photocatalytic treatment were not toxic toward methanogenic bacteria. The results demonstrate that photocatalysis can be used as a pre- or post-treatment method to biological anaerobic treatment of dye-containing textile wastewater.

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Radical yields in the radiolysis of cyclic compounds

Cited by 7 publications

References 10 publications

Role of the Low-Energy Excited States in the Radiolysis of Aromatic Liquids

Role of the Low-Energy Excited States in the Radiolysis of Aromatic Liquids

Effect of Gamma Irradiation on Fully Aliphatic Poly(Propylene/Neopentyl Cyclohexanedicarboxylate) Random Copolymers

Photocatalytic and combined anaerobic–photocatalytic treatment of textile dyes

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