Semiconductor-sensitized photodegradation of dichlorvos in water using TiO2 and ZnO as catalysts

Εvgenidou, Εleni; Fytianos, K.; Poulios, Ioannis

doi:10.1016/j.apcatb.2005.01.005

Cited by 315 publications

(125 citation statements)

References 35 publications

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“…Considering that dichlorvos is a unionizable compound, the increase of the reaction at alkaline pH can be ascribed to the high hydroxylation of the surface of the catalyst due to the presence of a large quantity of OH − ions. 26 Consequently, higher concentrations of OH· species are formed and the overall sonophotocatalytic degradation efficiency is enhanced. In Figure 4, it can be seen that for sonophotocatalysis at pH 10.3 and pH 7.3 present similar degradation extent.…”

Section: Methodsmentioning

confidence: 99%

“…The effect of pH on the sonophotocatalytic reaction is generally attributed to the surface charge of TiO 2 and its relation with the ionic form of the organic compound (anionic or cationic). 26 Electrostatic attraction or repulsion between the catalyst's surface and the organic molecule is taking place and consequently enhances or inhibits, respectively, the sonophotocatalytic COD Cr removal efficiency. The pollutant and thus the sonophotocatalytic degradation rates will be maximum near the point of zero charge of the catalyst as 6.8.…”

Section: Methodsmentioning

confidence: 99%

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Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Meng¹,

Shi²,

Ming³

et al. 2014

Bulletin of the Korean Chemical Society

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A magnetic sonophotocatalyst Fe 3 O 4 @SiO 2 @TiO 2 is synthesized for the enhanced biodegradability of organophosphate pesticide. The as-prepared catalysts were characterized using different techniques, such as Xray diffraction (XRD) and transmission electron microscopy (TEM). The radial sonophotocatalytic activity of Fe 3 O 4 @SiO 2 @TiO 2 nanocomposite was investigated, in which commercial dichlorvos (DDVP) was chosen as an object. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and enhancement of biodegradability. The effect of different factors, such as reaction time, pH, the added amount of catalyst on COD Cr removal efficiency were investigated. The average COD Cr removal efficiency reached 63.13% after 240 min in 12 L sonophotocatalytic reactor (catalyst 0.2 g L −1, pH 7.3). The synergistic effect occurs in the combined sonolysis and photocatalysis which is proved by the significant improvement in COD Cr removal efficiency compared with that of solo photocatalysis. Under this experimental condition, the BOD 5 / COD Cr ratio rose from 0.131 to 0.411, showing a remarkable improvement in biodegradability. These results showed that sonophotocatalysis may be applied as pre-treatment of pesticide wastewater, and then for biological treatment. The synthesized magnetic nanocomposite had good photocatalytic performance and stability, as when it was used for the fifth time, the COD Cr removal efficiency was still about 62.38%.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Meng¹,

Shi²,

Ming³

et al. 2014

Bulletin of the Korean Chemical Society

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“…Além disso, em condições de pH ácido a espécie predominante é o buraco, h bv + , menos reativo que HO• 14,19 . A maior constante de velocidade para remoção de cor (7,17x10 -2 min -1 ) nas proximidades do ponto isoelétrico de dióxido de titânio pode ser atribuída ao fato de o grupo carbonilamida estar na forma de dipolo e os grupos sulfônicos estarem ionizados, promovendo a adsorção do diazo corante negativamente carregado na superfície do catalisador na forma neutra de TiOH 21 . Isto também pode ser atribuído ao fato de que em solução neutra a alcalina, a espécie predominante seja o radical HO•, gerado pela oxidação de íon hidróxido disponível na superfície de TiO 2 .…”

Section: Efeito Do Phunclassified

Efeitos dos parâmetros operacionais na fotodegradação do azo corante direct red 23 na interface dióxido de titânio/água

Clausen¹,

Takashima²

2007

Quím. Nova

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Recebido em 13/11/06; aceito em 27/4/07; publicado na web em 16/10/07 EFFECTS OF OPERATIONAL PARAMETERS ON THE PHOTODEGRADATION OF DIRECT RED 23 AZO DYE AT THE TITANIUM DIOXIDE / WATER INTERFACE. The decolorization and degradation of direct red 23 azo dye have been investigated in aqueous suspension of titanium dioxide under artificial irradiation. The effects of some operational parameters such as azo dye concentration, catalyst loading, and solution pH were investigated at 30.0 °C and optimized values were obtained. The first-order kinetic model was used to discuss the results. The UV-Vis spectra changes showed that the azo dye sample, collected after 6 h irradiation, was 98% decolorized while the residual total carbon was 97.9% degraded, indicating simultaneous photodecolorization and degradation.Keywords: photocatalysis; diazo dye; titanium dioxide. INTRODUÇÃOA contaminação de águas naturais tem sido apontada como um dos maiores problemas da sociedade moderna. Dentro deste contexto, o setor têxtil apresenta especial destaque por utilizar grandes quantidades de água e por gerar grandes volumes de efluentes, os quais apresentam composição extremamente heterogênea 1 . Estes efluentes apresentam coloração intensa porque aproximadamente 20% da produção total de corantes são perdidos para o meio ambiente durante a etapa de tingimento das fibras 2 . Considerandose ainda que mais de 50% da produção mundial de corantes orgâni-cos sejam provenientes das indústrias têxteis, significa que se o tratamento não for adequado pode alterar o ecossistema, diminuindo a transparência da água e a penetração da radiação solar e, conseqüentemente, a atividade fotossintética e a solubilidade dos gases. Além disso, admite-se que o maior problema ambiental seja gerado pela utilização ampla de azo corante, de reconhecido efeito carcinogênico e mutagênico, já que representa cerca de 60% dos corantes consumidos atualmente no mundo 3 . O tratamento de efluentes têxteis tem sido realizado através da combinação de processos convencionais físicos, químicos e bioló-gicos, em virtude das características complexas e bio-resistentes 4 . No entanto, estes processos não são destrutivos, pois simplesmente transferem o composto orgânico do meio aquoso para outro meio causando poluição secundária. Devido às limitações dos processos convencionais para descoloração de efluentes têxteis, têm se buscado as tecnologias efetivas e economicamente viáveis para resolução desse impasse ambiental. Uma alternativa para reduzir os subprodutos e a cor desses efluentes são os Processos de Oxidação Avançados (POAs) que geralmente utilizam agentes oxidantes fortes e/ou catalisadores, como TiO 2 , na presença ou não de radiação para gerar radical hidroxila HO•. Este radical por ser altamente reativo é capaz de mineralizar as substâncias orgânicas presentes nos efluentes industriais 5 . Dentre os processos que produzem radical hidroxila, a fotocatálise heterogênea tem se mostrado no decorrer das duas úl-timas décadas como um dos métodos mais promissores na destruição d...

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“…Experimental studies on dependence of the reaction rate of degradation of organic compounds on temperature have been conducted (Evgenidou et al, 2005). Generally, increase in temperature enhances recombination of charge carriers and desorption process of adsorbed reactant species, resulting in decrease of photocatalytic activity.…”

Section: Temperature and Phmentioning

confidence: 99%

The Use of Artificial Neural Network (ANN) for Modelling, Simulation and Prediction of Advanced Oxidation Process Performance in Recalcitrant Wastewater Treatment

Elmolla¹,

Chaudhuri²

2011

Artificial Neural Networks - Application

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Semiconductor-sensitized photodegradation of dichlorvos in water using TiO2 and ZnO as catalysts

Cited by 315 publications

References 35 publications

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

Efeitos dos parâmetros operacionais na fotodegradação do azo corante direct red 23 na interface dióxido de titânio/água

The Use of Artificial Neural Network (ANN) for Modelling, Simulation and Prediction of Advanced Oxidation Process Performance in Recalcitrant Wastewater Treatment

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