A mechanistic study on photocatalysis by thiapyrylium salts. Photodegradation of dimethoate, alachlor and pyrimethanil under simulated sunlight

Gomis, J.; Arqués, A.; Amat, Ana M.; Marín, M. Luisa; Miranda, Miguel A.

doi:10.1016/j.apcatb.2012.04.025

Cited by 22 publications

(20 citation statements)

References 31 publications

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“…For instance, Gomis et al . studied photocatalytic degradation pathways of pyrimethanil in pure ACN . Photolysis experiments were carried out in a self‐made reactor equipped with a high‐pressure mercury lamp (HPL‐N 125 W/542 E27 SC; Phillips, Ivry‐sur‐Seine, France) delivering radiation at wavelengths ranging from 200 nm to 650 nm.…”

Section: Methodsmentioning

confidence: 99%

Structural characterization of photoproducts of pyrimethanil

Kinani

Rifai²,

Bourcier

et al. 2013

J. Mass. Spectrom.

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International audiencePyrimethanil is an anilino-pyrimidine fungicide particularly active against gray mold (Botrytis cinerea) and pear scab (Venturia inaequalis and Venturia pirina) on grapes, strawberries, tomatoes, fruits, vegetables and ornamental plants in greenhouses and open field situation.[1-5] According to the European Food Safety Authority, pyrimethanil has no evident mutagenic, genotoxic or carcinogenic potential, but a short-term toxicity study on rats and mice has shown an increase in liver weight accompanied by changes in the histopathology of the liver and thyroid.[6] To avoid these side effects, the concentration of pyrimethanil has been limited by legislation. The European Commission set the Maximum Residue Level of pyrimethanil at 10 mg/l in citrus fruits, 5 mg/l in pome fruits, strawberries, table and wine grapes and 0.05 mg/l in tree nuts (EC/600/2010).[7] It is thus important to increase our knowledge regarding the concentration of pyrimethanil in environmental matrices, its degradability and the factors affecting it. One of these factors is the photo alteration by sunlight, which is known to play a significant role in the degradation of this compound, due to the prolonged half-life (77 days approximately) of pyrimethanil in the environment.[8] Previous studies on the degradation of pyrimethanil were carried out mainly in a waste water treatment context and focused on the photo catalytic degradation using various salts as catalysts. Agüera et al.[9] used TiO2, Vanni et al.[10] and Anfossi et al.[11] added iron III, Navarro et al.[12] added ZnO and Gomis et al.[13] used thiopyrylium. Irradiation was carried out using a mercury or xenon lamp or direct sunlight. These studies have showed that a long irradiation time (between 150 and 1400 min, depending on the conditions and catalyst) is required for total disappearance of pyrimethanil. Degradation of pyrimethanil in water using the technique of photo-Fenton was investigated by Sirtori et al. They reported that the addition of sodium chloride accelerated the reaction and characterized four chlorinated photo-Fenton by-products.[14] The aim of the present study was the identification of UV-visible photo transformation products of pyrimethanil in water. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and gas chromatography coupled with multi stage mass spectrometry (GC-MSn) were used for analysis, with the aim of covering a large range of polarities for the detection of the potential transformation products. Elucidation of the structures of photoproducts was carried out performing high-resolution measurements and collision-induced dissociation (CID) experiments. Photolysis mechanisms have also been proposed to explain the formation of photo products of pyrimethanil in water

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Section: Methodsmentioning

confidence: 99%

Structural characterization of photoproducts of pyrimethanil

Kinani

Rifai²,

Bourcier

et al. 2013

J. Mass. Spectrom.

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“…Alachlor removal depended on both the irradiation time and the H2O2 concentration in a batch photocatalytic reactor where TiO2 nanoparticles were immobilized (Mahmoodi and Arami, 2010), while its poor degradation was obtained with an organic 2,4,6-triphenylthiapyrylium photocatalyst in a solar simulator (Gomis et al, 2012). 4-tert-octylphenol degradation was tested using a TiO2 precursor sol coated on the inner wall of a photoreactor at λ = 254 nm (Wu et al, 2012) as well as a NaBiO3 photocatalyst under visible radiation (Chang et al, 2010), in both cases up to 90% of the pol-lutant removal being obtained.…”

Section: Heterogeneous Photocatalysismentioning

confidence: 99%

An overview on the advanced oxidation processes applied for the treatment of water pollutants defined in the recently launched Directive 2013/39/EU

Ribeiro

Nunes

Pereira

et al. 2015

Environment International

806

319

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Environmental pollution is a recognized issue of major concern since a wide range of contaminants has been found in aquatic environment at ng L −1 to μg L −1 levels.In the year 2000, a strategy was defined to identify the priority substances concerning aquatic ecosystems, followed by the definition of environmental quality standards (EQS) in 2008. Recently it was launched the Directive 2013/39/EU that updates the water framework policy highlighting the need to develop new water treatment technologies to deal with such problem. This review summarizes the data published in the last decade regarding the application of advanced oxidation processes (AOPs) to treat priority compounds and certain other pollutants defined in this Directive, excluding the inorganic species (cadmium, lead, mercury, nickel and their derivatives).The Directive 2013/39/EU includes several pesticides

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“…In the case of TPTP + , despite its high intersystem crossing quantum yield (ISC = 0.93) [70] involvement of 1 (TPTP + )* was proposed in the removal of pyrimethanil or alachlor. [117] Therefore, it was necessary to perform a full mechanistic analysis of the participation of all the transient species to find out which one is responsible for the photodegradation of the selected contaminants.…”

Section: Resultsmentioning

confidence: 99%

“…Their photophysical properties are shown in Table 1. [103,111,116,117] A) B) ii) In the second study, direct detection of all the TPP + derived short-lived intermediates in the photocatalyzed oxidation of a mixture of pollutants using TPP + was proposed as a methodology to assess the photodegradation extent. iii) In the last study, the role of singlet and triplet excited states in the photocatalytic treatment of a mixture of pollutants, at different concentrations, was evaluated using TPTP + as photocatalyst.…”

Section: Contaminants Of Emerging Concernmentioning

confidence: 99%

“…The fast degradation in the case of CLOF could be attributed to the formation of stable byproducts that may favour the degradation reaction or to direct photolysis, seeFigure 28B.Direct photolysis control experiments (in the absence of TPTP + ) showed almost no reaction apart from CLOF, which suffered some direct photodegradation although much more slowly (Figure 28B). Plot of the relative concentration of ACF (■), ACP (■), CAF (■), CBZ (■)and CLOF (■) at Co= 5 mg L -1 each (1.3x10 -4 M global concentration)in aerated acidic 3) media, vs. time under solar simulated irradiation, in the presence of 10 mg L -1 (2x10 -5 M) of TPTP + (A) and in the absence of photocatalyst (B).The next step was the evaluation of the electron transfer from the singlet and from the triplet excited states of TPTP + and the formation of photoactive ground-state complexes, since previous studies have demonstrated that this photocatalyst is also able to act through all those pathways[103,111,116,117,140]. Therefore, every potential species that may participate in the photodegradation has to be evaluated for every pollutant and the combined results have to be analysed for each pollutant at different concentrations.First, fluorescence experiments (steady-state and time-resolved) were performed in deaerated acetonitrile to investigate the involvement of 1 (TPTP + ) * in the photodegradation of the pollutants, (Figure 29).…”

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confidence: 99%

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Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach.

Haya¹

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La tesis. La tesis doctoral. Un trabajo que no es un trabajo, es formación, es curiosidad, son ganas de aprender y de superarse, es creatividad, es responsabilidad y nervios… Pero sobre todo, es una etapa en la que te sumerges en la ciencia y así, casi sin darte cuenta, conoces a fondo esta bonita profesión. Se requiere cierta vocación, así como mucha dedicación y sobre todo, paciencia. Para mí, ha supuesto una etapa de mi vida de la que estoy muy orgullosa, en la que no solo he aprendido química o ciencia, sino que también me ha ayudado a evolucionar como persona y como profesional. Por todo esto, me gustaría mucho dar las gracias a quienes me dieron la oportunidad de vivir esta aventura, mis directores de tesis. A Miguel Ángel, por ser la luz que nos dirige a todos y todas cuando más lo necesitamos. Y a Marisa, para la que no tengo palabras, por ser la mejor profesora de química que he tenido, por su paciencia, su comprensión y su entusiasmo a la hora de enseñar, pero también por toda la ayuda y consejos de puertas afuera del laboratorio, he tenido mucha suerte. Y hablando de suerte y laboratorio, no puedo dejar de recordar a todos los compañeros y compañeras que hemos convivido en el 1A1 y en el 1A2, a Paula, Faber, Gemma y Vicky, Ofelia y Cris, Mauri, Paloma, a las nuevas incorporaciones Óscar y Alice, a las otras jefas Virginie, Chelo e Inma,… gracias por la ayuda y por todos los buenos momentos. ¡Ha sido un placer fotoquímic@s! Por otro lado, todo esto no habría sido posible sin financiación. Por lo que quiero agradecer, tanto al Severo Ochoa como a la Asociación Apadrina la Ciencia, por financiar mis contratos de investigación. También al DAAD, cuya financiación me permitió realizar mi estancia, donde conocí a una gran compañera, Leyre, a la cual también le estoy muy agradecida por esos seis meses en Regensburg. Ya por último, y a quienes más debo, muchísimas gracias a mi familia, a mis padres Felipe y Chelo, y a mi hermana Sara, por haberme apoyado durante toda mi vida en las decisiones más importantes, dándome ánimo y aliento. Gracias. Y para finalizar, gracias de todo corazón a quien ha sido mi pilar más fuerte durante esta etapa, Jorge. Contigo los retos son más fáciles, los sueños más bonitos y la vida más divertida. Por que sigamos construyendo pilares y aprendiendo juntos en el camino.

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A mechanistic study on photocatalysis by thiapyrylium salts. Photodegradation of dimethoate, alachlor and pyrimethanil under simulated sunlight

Cited by 22 publications

References 31 publications

Structural characterization of photoproducts of pyrimethanil

Structural characterization of photoproducts of pyrimethanil

An overview on the advanced oxidation processes applied for the treatment of water pollutants defined in the recently launched Directive 2013/39/EU

Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach.

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