Hydroxyl radical-induced oxidation of azo dyes: a pulse radiolysis study

Padmaja, S.; Madison, Stephen A.

doi:10.1002/(sici)1099-1395(199903)12:3<221::aid-poc119>3.0.co;2-u

Cited by 56 publications

(48 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The barrier to the addition of hydroxyl radicals to double bonds is less than that of hydrogen abstraction, so that in competition addition is often favored. When a hydroxyl radical reacts with aromatic compounds, it can add on across a double bond, resulting in hydroxycyclohexadienyl radical (Padmaja and Madison 1999). The resulting radical can undergo further reactions, such as reaction with oxygen, to give peroxyl radical, or decompose to phenoxyltype radicals by water elimination.…”

Section: Hydroxyl Radical (Oh)mentioning

confidence: 99%

Reactive Oxygen Species, Aging, and Antioxidative Nutraceuticals

Lee

Koo

Min

2004

Comp Rev Food Sci Food Safe

706

465

View full text Add to dashboard Cite

The important roles of reactive oxygen species in diseases related to aging and the necessity and benefits of antioxidative nutraceuticals in the prevention of diseases and promotion of healthy aging have been extensively reported in recent years. Oxygen is an essential component of living organisms. The generation of reactive oxygen species such as superoxide anion, hydrogen peroxide, hydroxyl radicals, and singlet oxygen is inevitable in aerobic metabolism of the body. Reactive oxygen species cause lipid oxidation, protein oxidation, DNA strand break and base modification, and modulation of gene expression. In the past several years, unprecedented progress has been made in the recognition and understanding of roles of reactive oxygen species in many diseases. These include atherosclerosis, vasospasms, cancers, trauma, stroke, asthma, hyperoxia, arthritis, heart attack, age pigments, dermatitis, cataractogenesis, retinal damage, hepatitis, liver injury, and periodontis, which are age-related. The body protects itself from the potential damages of reactive oxygen species. Its first line of defense is superoxide dismutases, glutathione peroxidases, and catalase. Scientists have indicated that antioxidant nutraceuticals supplied from daily diets quench the reactive oxygen species or are required as cofactors for antioxidant enzymes. Nutraceuticals play significant roles in the prevention of a number of age-related diseases and are essential for healthy aging. Epidemiological studies also reported the relevance of antioxidative nutraceuticals to health issues and the prevention of age-related diseases. Health-conscious consumers have made antioxidative nutraceuticals the leading trend in the food industry worldwide in recent years.

show abstract

Section: Hydroxyl Radical (Oh)mentioning

confidence: 99%

Reactive Oxygen Species, Aging, and Antioxidative Nutraceuticals

Lee

Koo

Min

2004

Comp Rev Food Sci Food Safe

706

465

View full text Add to dashboard Cite

show abstract

“…The final oxidation products may include some small molecular weight organic compounds and inorganic compounds such as carbon dioxide, HCO 3 -, CO 3 2-, NO 3 2-, SO 4 2-, etc. On the other hand, the reaction of OH • radical with the AR88 molecule might involve the formation of OH • adduct as the initial step and the subsequent elimination of water molecule from the intermediate product [35]:…”

Section: Degradation and Mineralization Of Ar88mentioning

confidence: 99%

Degradation of Azo Dye Acid Red 88 by Gas Phase Dielectric Barrier Discharges

Tang

Jiang

Zhang

et al. 2009

Plasma Chem Plasma Process

View full text Add to dashboard Cite

The degradation of an azo dye, acid red 88 (AR88) in aqueous solutions by a gas-phase dielectric barrier discharge (DBD) system was investigated. The reactive species generated from the DBD system such as OH • radical, ozone and hydrogen peroxide were measured. The effects of various parameters such as gas flow rate, initial pH, input power, initial concentration of AR88 and the gas source on the degradation of AR88 were studied. The results show that OH • radical was the major reactive species generated when 100% relative humidity (RH) air was used. An aqueous solution of 25 mg L -1 AR88 was 96.3% degraded in 5 min treatment, and 68% of the initial total organic carbon was removed in 90 min treatment with 100% RH air at 60 W input power and 7 L min -1 gas flow rate. The degradation kinetics of AR88 followed a pseudo-first-order reaction and was dependent on the input power, gas flow rate, initial AR88 concentration and initial pH.

show abstract

“…The presence of oxidation products such as phenol, quinone, catechol was also detected by many authors (Hsiao and Nobe 1993;Brillas et al 1998;Oturan 2000) in the case of the Electro-Fenton degradation of aromatic compounds. The degradation mechanism was corroborated by other authors (Padjama and Madison 1999;Oturan et al 2001). The identification of degradation products permits us to prove that the first step of azo dye degradation is the azo bond cleavage and the second step is hydroxyl radical addition on the aromatic ring.…”

Section: Degradation Productsmentioning

confidence: 99%

Degradation of azo dyes in water by Electro-Fenton process

Guivarch

Trevin

Lahitte

et al. 2003

Environmental Chemistry Letters

255

112

View full text Add to dashboard Cite

The degradation of the azo dyes azobenzene, pmethyl red and methyl orange in aqueous solution at room temperature has been studied by an advanced electrochemical oxidation process (AEOPs) under potentialcontrolled electrolysis conditions, using a Pt anode and a carbon felt cathode. The electrochemical production of Fenton's reagent (H 2 O 2 , Fe 2+ ) allows a controlled in situ generation of hydroxyl radicals ( · OH) by simultaneous reduction of dioxygen and ferrous ions on the carbon felt electrode. In turn, hydroxyl radicals react with azo dyes, thus leading to their mineralization into CO 2 and H 2 O. The chemical composition of the azo dyes and their degradation products during electrolysis were monitored by high performance liquid chromatography (HPLC). The following degradation products were identified: hydroquinone, 1,4-benzoquinone, pyrocatechol, 4-nitrocatechol, 1,3,5-trihydroxynitrobenzene and p-nitrophenol. Degradation of the initial azo dyes was assessed by the measurement of the chemical oxygen demand (COD). Kinetic analysis of these data showed a pseudo-first order degradation reaction for all azo dyes. A pathway of degradation of azo dyes is proposed. Specifically, the degradation of dyes and intermediates proceeds by oxidation of azo bonds and aromatic ring by hydroxyl radicals. The results display the efficiency of the ElectroFenton process to degrade organic matter.

show abstract

Hydroxyl radical-induced oxidation of azo dyes: a pulse radiolysis study

Cited by 56 publications

References 31 publications

Reactive Oxygen Species, Aging, and Antioxidative Nutraceuticals

Reactive Oxygen Species, Aging, and Antioxidative Nutraceuticals

Degradation of Azo Dye Acid Red 88 by Gas Phase Dielectric Barrier Discharges

Degradation of azo dyes in water by Electro-Fenton process

Contact Info

Product

Resources

About