Photocatalytic decolorization of Remazol Red RR in aqueous ZnO suspensions

Akyol, Abdurrahman; Yatmaz, H. Cengiz; Bayramoǧlu, Mahmut

doi:10.1016/j.apcatb.2004.05.021

Cited by 450 publications

(196 citation statements)

References 24 publications

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“…It is clearly seen that mill scale is a better catalyst in presence of (UV + H 2 O 2 ) for the degradation of RO4 dye also. The same trend was observed in earlier findings with azo reactive dyes (Lizama et al 2002;Akyol et al 2004). This was explained as: mill scale in presence of (UV + H 2 O 2 ) has greater quantum efficiency than mill scale in presence of (UV + OA).…”

Section: Ro4supporting

confidence: 78%

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

2015

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Photocatalytic degradation of two commercial dyes, Methylene Blue and Reactive Orange 4, in aqueous phase by mill scale (solid waste generated in steel plants) using advanced oxidation process was studied. The effects of various factors on the extent of degradation were investigated. These included: (1) the catalyst quantity, in the range 0.1-1.3 g/100 mL; (2) Methylene Blue concentration in the range 0.01-0.1 mM/100 mL; (3) Reactive Orange 4 concentration in the range 0.05-0.25 mM/100 mL; and (4) the concentration of hydrogen peroxide in the range 1-4/100 mL for Methylene Blue and 1-2/100 mL for Reactive Orange 4. The optimum catalyst dose in presence of hydrogen peroxide and UV illumination was found to be 0.8 and 0.3 g/100 mL for Methylene Blue and Reactive Orange 4, respectively. The decomposition rate was found to decrease with increasing dye concentration and increase with increasing hydrogen peroxide concentration.

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Section: Ro4supporting

confidence: 78%

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

2015

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“…Chemisorbed surface hydroxyl groups can enhance photocatalysis by trapping photoinduced holes resulting in an increase in the formation of the highly oxidizing OH • radicals. 77,78 It is well reported that silver retards the recombination of photogenerated electron hole pairs; 36,37,79 this may not only be due to the attraction of excited electrons to silver but also due to the presence of extra hydroxyl species to delay recombination through hole trapping.…”

Section: Resultsmentioning

confidence: 99%

A Systematic Study of the Effect of Silver on the Chelation of Formic Acid to a Titanium Precursor and the Resulting Effect on the Anatase to Rutile Transformation of TiO₂

et al. 2010

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Anatase to rutile transition in an unmodified synthetic titania usually occurs at a temperature range of 600-700°C. Various methods such as addition of metallic and nonmetallic dopants and modifying the precursor have previously been reported to influence the anatase to rutile transition temperature. In the current study, the effect of addition of increasing amounts of silver to the extent of chelation of a formate group to a titanium precursor and the resulting effects on the transformation of anatase to rutile has been studied. The addition of silver (0, 1, 3, and 5 mol %) on the anatase to rutile transformation temperature has been systematically followed by Fourier transform infrared (FTIR), Raman, X-ray diffraction (XRD), differential scanning calorimetry, and X-ray photoelectron spectroscopy (XPS) studies. From the FTIR and Raman spectroscopy studies it was observed that the incorporation of silver caused a reduction in the intensity of the COO -stretches indicating that the titania formate bridging complex is becoming weaker in the presence of silver. XRD studies indicated an early rutile formation for the silver-doped samples. XRD of the samples calcined at 700°Cshowed that 5 mol % Ag TiO 2 contained both anatase (46%) and rutile (54%), whereas the undoped sample primarily consists of anatase (95%). At 800°C all silver doped samples converted to 100% rutile and the undoped TiO 2 consisted of both anatase (55%) and rutile (45%). XPS analysis showed that Ag 0 and Ag 2 O has been formed on the surface of the titania formate complex without calcination (>100°C) indicating that photo-oxidation has occurred. FTIR, Raman, and XPS studies confirmed that the presence of silver in the xerogel before calcination may be responsible for the reduction of the titanium formate bridge. It was concluded that the presence of silver (Ag 2 O and Ag 0 ) hindered bridging ligands, which resulted in a weakened titanium gel network. This structurally weakened gel network could easily be collapsed during calcination, and it favors an early rutile formation.

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“…8,9 O semicondutor ZnO tem um bandgap de 3,37 eV em temperatura ambiente e é um dos mais importantes materiais inorgânicos, com propriedades catalítica, 10,11 elétrica, 12,13 opticoeletrônica, 14,15 e fotoquímica, 16 o que tem estimulado cada vez mais a ampla investigação em sua aplicabilidade. O uso do ZnO como material fotocatalisador para a degradação de poluentes ambientais tem sido vantajoso em relação a outros materiais devido à sua natureza não-tóxica, seu baixo custo e alta reatividade, 17,18 como também ocorre para o dióxido de titânio. O óxido de zinco tem sido sintetizado por vários métodos, tais como sol-gel, 19,20 de estado sólido, 21,22 de condensação da fase gasosa 23 e método químico de precipitação em fase líquida.…”

Section: Introductionunclassified

Nanocompósitos semicondutores ZnO/TiO2: testes fotocatalíticos

Silva¹,

Magalhães²,

Sansiviero³

2010

Quím. Nova

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Recebido em 8/1/09; aceito em 15/6/09; publicado na web em 25/11/09 ZnO/TiO 2 SEMICONDUCTOR NANOCOMPOSITES. PHOTOCATALYTIC TESTS. Titanium dioxide is an efficient photocatalist, being possible to improve its efficiency with better charge separation which occurs when it is coupled with other semiconductors. Nanometric particles of ZnO were used to impregnate TiO 2 P25 in order to optimize its photocatalytic properties. ZnO/TiO 2 composites were obtained at different proportions and were characterized by X-ray diffraction (XRD), micro-Raman and diffuse reflectance spectroscopies, measurement of surface area (BET) and scanning electron microscopy (SEM). Raman spectroscopy data revealed a change on the TiO 2 surface due the presence of ZnO which was observed by an enlargement of TiO 2 peaks and a change on the relation rate between anatase and rutile phases of the composites. The photodegradation of azo-dye Drimaren red revealed better efficiency for ZnO/TiO 2 3% nanocomposite and for ZnO pure.Keywords: semiconductor nanocomposites; photocatalysis, Raman spectroscopy. INTRODUÇÃOO dióxido de titânio é um semicondutor (E gap = 3,2 eV) que se encontra principalmente na forma de três estruturas cristalinas, anatásio, rutilo e brokita. A forma anatásio é aquela que apresenta maior atividade fotocatalítica, 1,2 sendo grandemente usado como fotocatalisador devido à sua alta eficiência e baixo custo. Algumas aplicações de grande relevância envolvendo o semicondutor TiO 2 são: fotocatálises assistidas por semicondutor para produzir combustíveis, tais como hidrogênio e, células solares baseadas em nanoestruturas de semicondutor. 3 O princípio de funcionamento do TiO 2 como fotocatalisador baseia-se na geração do par elétron-lacuna positiva, através da absorção de energia. 4 A luz UV é a fonte de energia mais comumente empregada. Sob irradiação, elétrons da banda de valência recebem energia suficiente para transpor a lacuna de energia do TiO 2 e podem, desta forma, serem transferidos para a banda de condução. As lacunas positivas são fortes agentes oxidantes e são responsáveis pela mineralização de vários compostos orgânicos. 5 Nos últimos 30 anos, vários estudos têm sido realizados para investigar as possíveis aplicações do TiO 2 como fotocatalisador. A maior parte desses estudos está concentrada no tratamento de sistemas aquosos contaminados por poluentes orgânicos considerados potencialmente tóxicos. 6 Materiais semicondutores nanoparticulados têm algumas propriedades peculiares e a elucidação destas propriedades tem levado à descoberta de diferentes campos da ciência e da tecnologia. 7 Nanopartículas de ZnO recentemente têm recebido grande atenção devido a uma variedade de aplicações tais como, absorção no UV, desodorização e tratamento antibacteriano. 8,9 O semicondutor ZnO tem um bandgap de 3,37 eV em temperatura ambiente e é um dos mais importantes materiais inorgânicos, com propriedades catalítica, 10,11 elétrica, 12,13 opticoeletrônica, 14,15 e fotoquímica, 16 o que tem estimulado cada vez mais a ampla investigação em...

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Photocatalytic decolorization of Remazol Red RR in aqueous ZnO suspensions

Cited by 450 publications

References 24 publications

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

A Systematic Study of the Effect of Silver on the Chelation of Formic Acid to a Titanium Precursor and the Resulting Effect on the Anatase to Rutile Transformation of TiO₂

Nanocompósitos semicondutores ZnO/TiO2: testes fotocatalíticos

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Photocatalytic decolorization of Remazol Red RR in aqueous ZnO suspensions

Cited by 450 publications

References 24 publications

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

Degradation of Commercial Dyes Using Mill Scale by photo-Fenton

A Systematic Study of the Effect of Silver on the Chelation of Formic Acid to a Titanium Precursor and the Resulting Effect on the Anatase to Rutile Transformation of TiO2

Nanocompósitos semicondutores ZnO/TiO2: testes fotocatalíticos

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A Systematic Study of the Effect of Silver on the Chelation of Formic Acid to a Titanium Precursor and the Resulting Effect on the Anatase to Rutile Transformation of TiO₂