Photoelectrocatalytic degradation of 4-chlorophenol and oxalic acid on titanium dioxide electrodes

Waldner, Georg; Pourmodjib, M; Bauer, R.; Neumann‐Spallart, M.

doi:10.1016/s0045-6535(02)00612-4

Cited by 122 publications

(73 citation statements)

References 16 publications

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“…Desta forma, o desenvolvimento de técnicas para imobilizar materiais semicondutores em suportes foi crucial no desenvolvimento desta área 29 . A oxidação fotoeletrocatalítica tem se mostrado eficaz no tratamento de diversas substâncias orgânicas que são poluentes ou danosas à saúde, como 4-clorofenol [30][31][32][33] , ácido fór-mico [34][35][36] e até organismos patogênicos 37 . Destaca-se também o tratamento dos corantes naftol azul 38 , remazol brilhante laranja 3R 39 e naftol azul preto (sobre WO 3 ) 40 , entre outros.…”

Section: Oxidação Fotocatalíticaunclassified

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

Catanho¹,

Malpass²,

Motheo³

2006

Quím. Nova

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Orange 3R and Remazol Golden Yellow RNL) using electrochemical and photoelectrochemical methods. In both methods, electrolysis experiments were performed at a current density of 50 mA cm -2 in an aqueous solution of each dye (30 mg L -1 ), using a photoelectrochemical flow-cell. For all the dyes studied, the photoelectrochemical method was demonstrated to be more efficient than the electrochemical one. Photoelectrochemical oxidation resulted in complete decoloration after 90 min of electrolysis and total organic carbon (TOC) removal reached up to 36%. It was observed that the dyes presenting chromophores at higher wavelengths are removed the quickest, which indicates that photosensitised (photoassisted) oxidation occurs. The level of color was reduced to levels below the standards presented in the literature, which indicates the viability of the photoelectrochemical process as part of the treatment of textile effluents.Keywords: azo dye; reactive dye; DSA. INTRODUÇÃOOs resíduos de indústrias têxteis possuem como característica uma intensa coloração a qual, em ambientes aquáticos, pode causar uma interferência nos processos de fotossíntese. Além disso, certas classes de corantes, assim como seus subprodutos, podem ser carcinogênicos e/ou mutagênicos 1 . Estudos 2 indicam que a poluição colorida de cursos d'água começa a ser observável a concentrações acima de 1 mg L -1 . Além disso, resíduos da indústria têxtil podem conter metais pesados em níveis acima dos permitidos pelas leis ambientais 3 .A produção mundial de corantes e pigmentos é estimada entre 750.000 e 800.000 t/ano 2,3 sendo que cerca de 26.500 t/ano são consumidas no Brasil 1 . Desta quantidade, aproximadamente 12% dos corantes orgânicos são perdidos durante as etapas de produção e processamento 1 . Esta perda é relativamente pequena comparada com outros poluentes, como pesticidas, solventes e detergentes 1 ; porém, é importante enfatizar que a aplicação destes materiais geralmente envolve diluição, gerando um grande volume de efluente líquido.A classificação dos corantes pode ser pelo tipo de fibra, tais como corantes para nylon, algodão, poliéster, etc.; pelos métodos de aplicação no substrato, ou seja, pela maneira que eles são fixados à fibra têxtil (corantes diretos, reativos, à cuba, etc.), e de acordo com a sua estrutura química, como por ex.: azo, antraquinona, indigóides, etc.) 4-7 . Cerca de 60% dos corantes utilizados em indústrias têxteis são corantes azos, que se caracterizam pelo grupo -N=N-ligados a sistemas aromáticos 1 , sendo que a função azo inclui os principais tipos de corantes reativos. Os corantes reativos contêm um grupo eletrofílico (reativo) capaz de formar ligação covalente com grupos hidroxila das fibras celulósicas, com grupos amino, hidroxila e tióis das fibras protéicas e também com grupos amino das poliamidas. Devido às grandes quantidades de corantes que não são fixados às fibras e são liberados no processamento têxtil, é importante que seja estudada a degradação destes corantes em condições (de pH, condutividade, etc....

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Section: Oxidação Fotocatalíticaunclassified

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

Catanho¹,

Malpass²,

Motheo³

2006

Quím. Nova

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“…A method for achieving that goal is to modify the TiO 2 intrinsic properties [22][23][24] by doping it with metal, non metal and ions or by improving the geometrical properties of the nanostructure. An alternative method for hindering the photogenerated pairs recombination consists in applying an external potential bias [25][26][27][28][29][30][31] to a thin TiO 2 layer deposited on a conductive support. The photoelectrocatalytic (PEC) method, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…The anodizing method, widely used by several authors [35][36][37][38], allows to prepare Ti/TiO 2 electrodes by anodizing titanium metal in acidic [39][40][41] or alkaline [42] solution. The sol-gel method has been also used by many authors [31,43,44]; the Ti/TiO 2 electrode was prepared by coating a layer of TiO 2 sol onto the titanium substrate via repetitive heat treatments. The chemical deposition method is also able to prepare photoanodes with TiO 2 thin films.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrocatalytic selective oxidation of 4-methoxybenzyl alcohol in water by TiO2 supported on titanium anodes

Özcan

Yurdakal

Augugliaro

et al. 2013

Applied Catalysis B: Environmental

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a b s t r a c tThe photoelectrocatalytic partial oxidation of 4-methoxybenzyl alcohol in aqueous solution irradiated by near-UV light was carried out in a three-electrode batch reactor. TiO 2 films were either deposited by dip-coating of a TiO 2 sol onto a Ti foil and subsequent calcination or generated on Ti plates by thermal oxidation in air at 400-700 • C. The effects of the anode preparation method and bias potential values on conversion and selectivity to the corresponding aldehyde were investigated. The photoelectrocatalytic results were compared with the photocatalytic and electrocatalytic ones. The results indicated that no reaction occurred during the electrocatalytic experiments, whereas the photocatalytic reactivity was positively influenced by the application of a small bias (0.75 V vs. saturated calomel electrode). By applying the previous bias the highest initial degradation rates, r 0 , and selectivities to 4-methoxybenzaldehyde, S, were obtained in photoelectrocatalytic experiments by using Ti plate calcined at 500 • C (r 0 = 0.1507 mM h −1 , S = 85%) or TiO 2 film prepared by dip-coating and calcined at 700 • C (r 0 = 0.1339 mM h −1 , S = 90%). In order to investigate the influence of the substituent groups on reactivity and selectivity, photoelectrocatalytic runs with benzyl alcohol, 2-methoxybenzyl alcohol, 3-methoxybenzyl alcohol, 2,4-dimethoxybenzyl alcohol, 2,3,4-trimethoxybenzyl alcohol, 4-nitrobenzyl alcohol and 4-hydroxybenzyl alcohol have been performed. The selectivity and reactivity values increased by increasing the electron-donor properties of the substituent groups. This positive effect, however, was obtained only if the electron-donor group is in para or ortho position with respect to the alcoholic group.

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“…In more recent years the electrochemical detection of chlorophenols and the development of an electrochemical sensor for these compounds have been investigated intensively together with their degradation and adsorption [6][7][8]. Different bare electrode materials such as gold, platinum, glassy carbon and boron doped diamond electrodes have been tested [4,[9][10][11][12][13] as well as modified electrodes with different kinds of catalysts [14,15].…”

Section: Introductionmentioning

confidence: 99%

The electrochemical detection of 4-chlorophenol at gold electrodes modified with different phthalocyanines

Peeters

Wael

Bogaert

et al. 2008

Sensors and Actuators B: Chemical

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Because of their toxicity to humans and their tendency to bioaccumulate in the food chain, the detection of chlorophenols has been investigated intensively. This paper compares the oxidation of 4-chlorophenol on a bare gold electrode to its detection on gold electrodes electrochemically modified with either cobalt(II) tetrasulphonated phthalocyanine (CoTSPc) or 3,4 ,4 ,4 -copper(II) tetrasulphonated phthalocyanine (CuTSPc). Results show that the electrochemical behaviour of 4-chlorophenol depends on the molecular structure of the phthalocyanine thin film layers on the gold surface. In addition, the influence of the coordinating properties of the phthalocyanines on the sensitivity of the measurement and the fouling of the electrode material is discussed.

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Photoelectrocatalytic degradation of 4-chlorophenol and oxalic acid on titanium dioxide electrodes

Cited by 122 publications

References 16 publications

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

Avaliação dos tratamentos eletroquímico e fotoeletroquímico na degradação de corantes têxteis

Photoelectrocatalytic selective oxidation of 4-methoxybenzyl alcohol in water by TiO2 supported on titanium anodes

The electrochemical detection of 4-chlorophenol at gold electrodes modified with different phthalocyanines

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