The role of singlet molecular oxygen in the photodegradation of 1-arylazo-2-naphthols in methanol and on cotton

Jansen, Lisinka; Wilkes, Ian; Wilkinson, Frances; Worrall, David R.

doi:10.1016/s1010-6030(99)00095-7

Cited by 21 publications

(9 citation statements)

References 29 publications

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“…Several methods including advanced oxidation processes have been developed for this purpose. The degradation of these dyes to eliminate color and partial mineralization is achieved by photolysis in the presence of H 2 O 2 , − photocatalytic and TiO 2 catalyst, − Fenton's reaction, , sonolysis, − enzyme-catalyzed oxidation, and radiolysis by gamma and high-energy electron beams. , Oxidation by singlet oxygen also contributes to the photodegradation of arylazo naphthol dyes. However, for dyed fabrics, it is necessary that the dyes should remain fast to potential oxidation during normal washing processes , and through interactions with the base fabric. , Azo compounds are reduced by the intestinal anaerobic bacteria through scission of azo bonds to form aromatic amines, which are toxic to living organisms.…”

Section: Introductionmentioning

confidence: 99%

Free-Radical-Induced Oxidation and Reduction of 1-Arylazo-2-naphthol Dyes: A Radiation Chemical Study

et al. 2002

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The kinetics and transient optical absorption spectra of the intermediates formed in the reaction of •OH, N3 •, and e- aq with 1-arylazo-2-naphthol and its ortho- and para-substituted chloro, methyl and methoxy derivatives at pH 7.0 have been studied by pulse radiolysis. The rate constants for the reaction of •OH and the nucleophilic hydrated electron (e- aq) with these compounds are (1.0−1.2) × 1010 M-1 s-1 and (0.8−2.5) × 1010 M-1 s-1. The reaction of N3 • with these azo dyes is more selective (ρ+ = −2.0) with the rate constants varying between 0.1 × 109 and 8 × 109 M-1 s-1 depending upon the substituent. The transient optical absorption spectra of the intermediates formed in the reaction of the dyes with •OH are different from the corresponding spectra of the intermediates observed in the reaction of the dyes with N3 •. The •OH radical reacts with the dyes by addition to form the •OH adducts, whereas N3 • reacts with the dyes by direct one-electron transfer to form the one-electron oxidized dye radical. The pK A of the dye radical of the para-methoxy derivative was determined to be 5.2. This radical decays bimolecularly, predominantly by disproportionation, whereas the •OH adducts of the dyes also decay bimolecularly but predominantly by dimerization. The initially formed radical anion in the reaction of e- aq with the unsubstituted dye protonates rapidly to give the hydrazyl radical, which decays bimolecularly by disproportionation. Of the radicals studied, the •OH-induced oxidation of the dyes is the most effective process leading to decolorization of the dyes at pH 7.0.

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Section: Introductionmentioning

confidence: 99%

Free-Radical-Induced Oxidation and Reduction of 1-Arylazo-2-naphthol Dyes: A Radiation Chemical Study

et al. 2002

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“…Reactive Black 5) was provided by Transfar Group Co., Ltd (Hangzhou, China) and recrystallized from dimethylformamide and diethylether. 17 The chemical structure of the dye RB5 is shown in Scheme 1. NaCl, sodium sulfate, sodium carbonate and sulfuric acid were of analytical purity and were used as received from Sinopharm Chemical Reagent Co., Ltd. High purity water (resistivity ¼ 18.2 MÁcm) made by a Master-S plus UVF ultra pure water system (Hitech Instruments Co., Ltd, China) was used throughout the study.…”

Section: Chemicalsmentioning

confidence: 99%

Effect of NaCl concentrations on the photodecoloration of reactive azo-dyes and their cotton dyeings

Chen

Dong

et al. 2014

Textile Research Journal

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The color fastness of reactive cotton dyeings under simultaneous exposure to light and saline water, as well as light and perspiration, is one of the most important characteristics especially for summer-time sportswear. In order to illustrate the dual effects (i.e. favorable or adverse) of saline water on the photofading of reactive azo-dyes, the degradation mechanism and reaction kinetics of dye photodecoloration in the presence of various NaCl concentrations were investigated in simulated experiments. Experimental results indicated that the photodecoloration of dye solution was mainly attributed to the hydroxyl radical. Due to the quenching of the hydroxyl radical by the chloride ion, the dye photodecoloration rate decreased with low NaCl concentration (<10 g/L). Nevertheless, higher NaCl concentration (>50 g/L) was beneficial to produce reactive chlorine species, resulting in a significant increase of the photodecoloration rate. Moreover, reaction kinetic analysis demonstrated that the observed first-order rate constant for the photodecoloration of dye solution consistently increased with the increasing NaCl concentration.

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“…For example, it has been shown that singlet molecular oxygen is efficiently produced in the liquid phase via sensitization upon irradiation of organic molecules in the presence of molecular oxygen and can contribute to the photodegradation of e.g. 1‐(arylazo)‐2‐naphthols in acetonitrile (23). Because many photofunctional materials are employed in the solid state ( e.g.…”

Section: Introductionmentioning

confidence: 99%

Pyrophthalones as Blue Wavelength Absorbers in Thermoplastic Media

Natarajan

Burns

Takemori

et al. 2011

Photochem & Photobiology

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We have explored the utility of pyrophthalones as violet-blue light filtering dyes in polymer matrices for wavelengths below 450 nm. Further, we have investigated the photodegradation of these molecules in thermoplastic media and the mechanisms behind their degradation. Finally, a range of additives have been explored to improve the photostability of these molecules to achieve the desired performance.

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The role of singlet molecular oxygen in the photodegradation of 1-arylazo-2-naphthols in methanol and on cotton

Cited by 21 publications

References 29 publications

Free-Radical-Induced Oxidation and Reduction of 1-Arylazo-2-naphthol Dyes: A Radiation Chemical Study

Free-Radical-Induced Oxidation and Reduction of 1-Arylazo-2-naphthol Dyes: A Radiation Chemical Study

Effect of NaCl concentrations on the photodecoloration of reactive azo-dyes and their cotton dyeings

Pyrophthalones as Blue Wavelength Absorbers in Thermoplastic Media

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