Mechanism of photodegradation of aqueous organic pollutants. 1. EPR spin-trapping technique for the determination of hydroxyl radical rate constants in the photooxidation of chlorophenols following the photolysis of hydrogen peroxide

Kochany, Jan; Bolton, James R.

doi:10.1021/j100166a039

Cited by 93 publications

(63 citation statements)

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“…37 Kochany has shown that the competition of various chlorophenols with DMPO toward • OH radicals in H 2 O 2 solution obeys a linear SternVolmer relationship. 38 However, recent results derived by Colussi with DMPO in aqueous TiO 2 suspensions display a nonlinear effect of dichlorobenzene toward the generation of DMPO-OH. 13 To investigate the effect of different sodium salts, 3-carboxyproxyl was used as a spin trap for hydroxyl radicals.…”

Section: Resultsmentioning

confidence: 95%

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions

and¹,

Turro²,

and³

et al. 1997

J. Phys. Chem. B

219

122

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The generation of hydroxyl ( • OH) radicals produced by irradiation of aqueous TiO 2 suspensions was investigated by electron paramagnetic resonance (EPR) and product analysis employing a stable free nitroxide radical (3-carboxyproxyl) as a spin trap of • OH. Product analysis demonstrated that the attack of • OH on 3-carboxyproxyl produces a diamagnetic product (proxyl-NH) with a trapping efficiency of ca. 80%. It could also be shown that a small amount of the nitroxides is reduced by conducting band electrons. The rate of formation of • OH could be determined by monitoring the time dependence of the decrease in the concentration of 3-carboxyproxyl monitored by EPR spectroscopy or the time dependence of the increase in the concentration of proxyl-NH monitored by gas chromatography analysis. The rate of formation of • OH serves as a mechanistic parameter to investigate the mechanism of formation of this reactive species by the photoexcitation of TiO 2 . The dependence of the rate of formation of • OH was shown to be a linear function of light intensity at low intensities. It was observed that molecular oxygen, a good scavenger of conduction band electrons, only slightly influences the rate of formation of • OH and supports the production of • OH from photogenerated holes. Addition of selected anions to the photolysis mixtures results in a diminished rate of disappearance of the spin trap as the result of a competition between the spin trap and the anion for • OH. From a SternVolmer analysis of the data, the rate constant for the reaction of hydroxyl radicals with the anions was determined.

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Section: Resultsmentioning

confidence: 95%

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions

and¹,

Turro²,

and³

et al. 1997

J. Phys. Chem. B

219

122

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“…Various studies show that the rate of photolysis of chlorophenols depends on the pH of the reaction environment [8,9,26,30,[32][33][34][35] and on the structure of the molecule-particularly the positioning of the chlorine atom relative to the hydroxyl group [13,23,29,30,33,35,[37][38][39][40][41].…”

Section: Direct Photolysismentioning

confidence: 99%

“…Hydroxyl radicals can react with organic substances by: electron transfer, H • abstraction, or • OH addition to an aromatic ring [45,46]. The present paper discusses results of kinetic investigations of the reactions of chlorophenols with hydroxyl radicals, generated by adding H 2 O 2 to irradiated aqueous solutions of these compounds [14,[23][24][25][26]34,35,40,[47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64].…”

Section: Kinetics Of Reactions With • Oh Radicalsmentioning

confidence: 99%

Photo-degradation of chlorophenols in the aqueous solution

Czaplicka

2006

Journal of Hazardous Materials

251

152

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“…One of the methods is the electron spin resonance spectroscopy (ESR), which measures the electron paramagnetic resonance spectrum of a spin adduct derivative after trapping [11,12]. But this method is insensitive and cannot be employed readily to acquire quantitative estimate of • OH production because the • OH adduct is not stable.…”

Section: Introductionmentioning

confidence: 99%

Determination of hydroxyl radicals in advanced oxidation processes with dimethyl sulfoxide trapping and liquid chromatography

Tai

Peng

Liu

et al. 2004

Analytica Chimica Acta

253

109

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In this paper, a simple and sensitive method for the determination of hydroxyl radicals generated in advanced oxidation processes is described. The proposed method employed the reaction between hydroxyl radicals and dimethyl sulfoxide (DMSO) to generate quantitatively formaldehyde, which then reacted with 2,4-dinitrophenylhydrazine (DNPH) to form the corresponding hydrazone (HCHO-DNPH) and analyzed by liquid chromatography-UV. Factors affecting the derivatization reaction of HCHO and trapping reaction of hydroxyl radicals, as well as the applicability of the method, were investigated. The detection limit for hydroxyl radicals was 0.54 mol L −1 . The method had been used to determine the yield of hydroxyl radicals in various advanced oxidation processes (AOPs) to compare their oxidation ability.

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Mechanism of photodegradation of aqueous organic pollutants. 1. EPR spin-trapping technique for the determination of hydroxyl radical rate constants in the photooxidation of chlorophenols following the photolysis of hydrogen peroxide

Cited by 93 publications

References 0 publications

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions

Photo-degradation of chlorophenols in the aqueous solution

Determination of hydroxyl radicals in advanced oxidation processes with dimethyl sulfoxide trapping and liquid chromatography

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Mechanism of photodegradation of aqueous organic pollutants. 1. EPR spin-trapping technique for the determination of hydroxyl radical rate constants in the photooxidation of chlorophenols following the photolysis of hydrogen peroxide

Cited by 93 publications

References 0 publications

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO2Suspensions

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO2Suspensions

Photo-degradation of chlorophenols in the aqueous solution

Determination of hydroxyl radicals in advanced oxidation processes with dimethyl sulfoxide trapping and liquid chromatography

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Product

Resources

About

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions

A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO₂Suspensions