Role of oxidative and reductive pathways in the photocatalytic degradation of organic compounds

Pelizzetti, Ezio; Minero, Claudio

doi:10.1016/s0927-7757(98)00580-9

Cited by 56 publications

(32 citation statements)

References 31 publications

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“…In the presence of 0.1 mmol/L KI, the rate constant decreased to 0.0022 min −1 , which was only 10.4% of that in the absence of KI. This indicated that the total contribution of HO • radicals and holes to the degradation of AO7 was 89.6% and the total contribution of direct oxidation of other active species, such as O 2 •− , HO 2 [30,31]. A comparison was made between the original decolorization curves of AO7 solution which were obtained after adding catalase (500 mg/L) into the initial solution.…”

Section: The Roles Of the Three Degradation Pathwaysmentioning

confidence: 99%

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Zhang

Sun

et al. 2008

Journal of Photochemistry and Photobiology A: Chemistry

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a b s t r a c tA novel microwave electrodeless lamp (MWL) was used as the light source for microwave assisted TiO 2 photocatalysis to degrade azo dye Acid Orange 7 (AO7). This technique aims to provide a new way to study the synergetic effect of both UV-vis light and microwave irradiations on aqueous solution of catalysts. The roles of active oxygen species in the photodegradation of AO7, such as hydroxyl radical (HO • ), positive holes (h + ) and hydrogen peroxide (H 2 O 2 ), were investigated to understand the photodegradation mechanism. The presence and roles of these oxidative species were examined using appropriate quenchers. It was found that the degradation of AO7 proceeded via three pathways, namely, UV-induced photocatalytic degradation, visible light-induced dye self-photosensitized degradation and direct photolytic degradation. The percentages of dye degradation by the three pathways were about 31.1%, 39.0% and 19.5%, respectively.

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Section: The Roles Of the Three Degradation Pathwaysmentioning

confidence: 99%

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Zhang

Sun

et al. 2008

Journal of Photochemistry and Photobiology A: Chemistry

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“…Nitrogen-containing moieties in organic compounds can be transformed photocatalytically into either N 2 , NH 3 /NH 4 + , and/or nitrite and nitrate ions, the ratio depending on the different features of the Ncontaining structure. [22,23] Moreover, the relative amount of ammonium and nitrate formation is related to the initial transformation mechanism. The final fate of organic nitrogen in photocatalytic processes has been reported to be essentially related to the initial oxidation state of nitrogen in the organic compounds, [24,25] the presence/absence of oxygen and, in few cases, the structure of the organic compound (e.g., 4-nitrosophenol vs nitrosobenzene).…”

Section: [Màh]mentioning

confidence: 99%

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Calza

Medana

Baiocchi

et al. 2006

Chemistry A European J

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The light-induced degradation of alkylurea derivatives under simulated solar irradiation has been investigated in aqueous solutions containing TiO(2) as a photocatalyst. Herein, we will focus on how the presence of one or more methyl (or ethyl) groups on urea modifies the kinetics of disappearance and influences both the ratio and the extent of the inorganic nitrogen formation caused by different degradation pathways. In the present work, we have elucidated a mechanism for the formation of transformation products of the alkyl derivatives by combining several analytical and spectroscopic procedures and the theoretical simulation of ab initio calculations. In all cases, N-demethylation represents only a secondary pathway, while the main transformation proceeds through an unexpected cyclization, involving (m)ethyl- and di(m)ethylureas with the formation of (methyl)amino-2,3-dihydro-1,2,4-oxadiazol-3-one as the principal intermediate of the reaction (with a yield of 60 %). This behaviour is rather unexpected and in contrast with the typical photocatalyzed transformation pathways, which proceed through the formation of more simple structures.

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“…In silver/titania suspensions, the fact that the rates of sucrose mineralisation decreased with silver/titania particles under oxygen-enriched conditions suggests that at a sufficiently high dissolved oxygen concentration, oxygen molecules begin to compete effectively for electrons on the silver sites which may be required for a possible reduction reaction involving organic intermediate species generated during the reaction [14,44,45]. Thus, in the presence of silver deposits on titania particles, it is postulated that the reduction of oxygen molecules as well as organic species can occur on silver deposits [45,46].…”

Section: Photocatalytic Mineralisation Of Sucrose Salicylic Acid Andmentioning

confidence: 99%

Silver metallisation of titania particles: effects on photoactivity for the oxidation of organics

Vamathevan

Amal

Beydoun

et al. 2004

Chemical Engineering Journal

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Role of oxidative and reductive pathways in the photocatalytic degradation of organic compounds

Cited by 56 publications

References 31 publications

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Silver metallisation of titania particles: effects on photoactivity for the oxidation of organics

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Role of oxidative and reductive pathways in the photocatalytic degradation of organic compounds

Cited by 56 publications

References 31 publications

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Investigation of the roles of active oxygen species in photodegradation of azo dye AO7 in TiO2 photocatalysis illuminated by microwave electrodeless lamp

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO2 Dispersion

Silver metallisation of titania particles: effects on photoactivity for the oxidation of organics

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Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion