Photocatalytic transformation of pesticides in aqueous titanium dioxide suspensions using artificial and solar light: intermediates and degradation pathways

Konstantinou, Ioannis; Albanis, Triantafyllos A.

doi:10.1016/s0926-3373(02)00266-7

Cited by 564 publications

(281 citation statements)

References 119 publications

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“…At higher concentrations of filler in the polymeric films (2.5 and 3 phr of GO x ), the photodegradation efficiency levels off, and no further improvement was obtained by increasing the GO x content up to 3 phr, similar to what was already documented with high TiO 2 content [17]. This phenomenon is attributable to the photonic efficiency level off at high catalyst concentration, when the increased light scattering reduces the photonic flux within the irradiated solution thus lowering the degradation rate [2]. All these data strongly support the evidence of a photocatalytic activity of the GO x dispersed within the epoxy network together with a certain degree of adsorption, which in any case will help the removal of the pollutants from water.…”

Section: Photodegradation Activitysupporting

confidence: 61%

“…and for the epoxy formulation containing, respectively, 1 phr (filled triangle), 2 phr (filled diamond), and 3 phr (filled square) of GO x . Film thickness 25 μm, light intensity 30 mW/cm 2 While the slope of the curves gives an information of the kinetic of the process, the plateau value gives the final epoxy group conversion.…”

Section: Photo-curing Process and Film Characterizationmentioning

confidence: 99%

“…It is well known that irradiation of TiO 2 with an energy source higher than its band gap produces electrons and holes in the conduction band and valence band, respectively. These photogenerated holes and electrons can combine with the surfaceadsorbed species (e.g., water and oxygen) to form highly reactive radical species such as hydroxyl radical and superoxide radical anion and can completely mineralize most organic compounds [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Graphene oxide–epoxy hybrid material as innovative photocatalyst

2013

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New photocatalytic materials prepared by dispersing graphene oxide (GO x ) into UV-curable epoxy resin can be classified as semiconductors and thanks to this behavior it can be used in order to activate photoxidative process in a similar way as it happens with the well-known TiO 2 . The activity of these new photocatalytic materials was evaluated in aqueous phase; photoactivity was determined by following the photodegradation of phenol during irradiation in the presence of epoxy crosslinked films containing GO x .

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Section: Photodegradation Activitysupporting

confidence: 61%

Section: Photo-curing Process and Film Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Graphene oxide–epoxy hybrid material as innovative photocatalyst

2013

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“…Some molecules studied include phenol, chlorophenol, organo-chlorinated compounds, and other dyes, 5,6 all of which are common pollutants found in industrial effluents. Molecular degradation and kinetics parameters were determined in these studies using UV-Visible (UV-Vis) electronic spectroscopy and mass spectrometry.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Cordeiro

Cório

2009

J. Braz. Chem. Soc.

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Este trabalho apresenta o estudo do comportamento fotoquímico de hidrocarbonetos policíclicos aromáticos (HPAs), potenciais poluentes secundários em reações em aerossóis, através de espectroscopia Raman em comparação com seu comportamento eletroquímico. Os HPAs estudados incluem pireno, antraceno, fenantreno e fluoreno. Esses foram adsorvidos sobre o catalisador TiO 2 e irradiados com radiação ultravioleta (254 nm). A oxidação eletroquímica foi estudada via espectroscopia Raman intensificada pela superfície (SERS) in situ e levou à formação de produtos carbonilados. Intermediários oxidados contendo o grupo C=O foram também observados nos processos de fotodegradação. A comparação entre os intermediários formados nos processos fotoquímicos e eletroquímicos revela produtos idênticos para o antraceno, mas não para o pireno. Esse resultado advém da diferença de mecanismo para esses dois processos. A degradação fotocatalítica sobre TiO 2 é iniciada por radicais hidroxila, enquanto a oxidação eletroquímica é iniciada por transferência eletrônica direta com o HPA adsorvido no eletrodo, gerando cátions radicais do HPA que desencadeiam as reações subseqüentes. This paper presents the study of photochemical behavior of polycyclic aromatic hydrocarbons (PAHs), potential pollutants in secondary reactions in aerosols, through Raman spectroscopy compared with its electrochemical behavior. The PAHs studied include pyrene, anthracene, phenanthrene and fluorene. These were adsorbed onto TiO 2 and irradiated with ultraviolet light (254 nm). Their electrochemical oxidation was studied by in situ Surface-enhanced Raman Scattering (SERS) and led to the formation of carbonyl-containing products. Oxidized intermediates bearing the C=O group were also formed during photodegradation. The joint analysis of the photodegradation data with those produced by electrochemical means -using spectroscopic techniques for the identification and characterization of the products -revealed the formation of identical products for anthracene, but not for pyrene. A reasonable explanation for this difference in results is that photochemical and electrochemical oxidation reactions proceed via different mechanisms. While photocatalytic degradation over TiO 2 is initiated by hydroxyl radicals, electrochemical oxidation is initiated by the direct electron transfer from adsorbed PAH to the electrode, generating PAH cation radicals that undergo subsequent reactions.Keywords: advanced oxidative processes, photocatalysis, TiO 2 , spectroelectrochemistry, SERS IntroductionExcessive concentrations of particulate matter in the atmosphere are cause for significant concern in many metropolitan areas around the world. This particulate matter exhibits dynamic behavior owing to potential chemical and photochemical reactions, changing its composition according to time and environment. Polycyclic aromatic hydrocarbons (PAHs), a class of chemicals present in particulate matter, are of special interest due to their mutagenic and carcinogenic properties. 1,2 PAHs are character...

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“…19 Since methylparathion contains a nitro group and sulfur and phosphorous atoms, are potential ionic degradation by-products. 26 After 8 h of irradiation the reduction peak of methylparathion (-0.5 V) are displaced to less negative potentials, indicating an electrocatalytical process or transformation to other by-product. The very complex voltammetric behavior observed for methylparathion after several hours of irradiation indicates the necessity of additional electrochemical studies of such process.…”

Section: (A) and Absorbance Spectra (B) Ph=30 Adjusted With Hclmentioning

confidence: 95%

Electrochemical behavior of parent and photodegradation products of some selected pesticides

et al. 2008

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Recebido em 9/4/07; aceito em 15/2/08; publicado na web 31/7/08Electrochemical behavior of pesticides is extensively studied, but little attention has been given to the study of their degradation products (by-products) by electrochemical methods. However, the degradation products of pesticides can be even more toxic then the parent products and such studies should be encouraged. Therefore, the objective of this work was to evaluate the electroactivity of by-products of imazaquin, methylparathion, bentazon and atrazine, generated by UV irradiation and measured using cyclic and differential pulse voltammetry and UV-visible absorption spectrophotometry. Results have shown that several by-products exhibit electroactivity, allowing, in some cases, the simultaneous determination of both parent and degradation products.

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Photocatalytic transformation of pesticides in aqueous titanium dioxide suspensions using artificial and solar light: intermediates and degradation pathways

Cited by 564 publications

References 119 publications

Graphene oxide–epoxy hybrid material as innovative photocatalyst

Graphene oxide–epoxy hybrid material as innovative photocatalyst

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Electrochemical behavior of parent and photodegradation products of some selected pesticides

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