Laboratory- and pilot-plant-scale photodegradation of chloroaliphatics in aqueous solution by photocatalytic membranes immobilizing titanium dioxide

Bellobono, Ignazio Renato; Carrara, Anna; Barni, Barbara; Gazzotti, Aleardo

doi:10.1016/1010-6030(94)03844-9

Cited by 59 publications

(25 citation statements)

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“…The concentration of chloride ion was determined by ion chromatography with a conductivity detector (Shimadzu HIC-6A). [17,18]. In addition to the characteristic peak of 101 plane, diffraction peaks corresponding to rutile titania also appeared on the pattern at 2 = 27. where I A denotes the intensity of the strongest anatase reflection, and I R is the intensity of the strongest rutile reflection.…”

Section: Methodsmentioning

confidence: 97%

Enhanced photocatalytic activity of TiO2 by doping with Ag for degradation of 2,4,6-trichlorophenol in aqueous suspension

Selvaraj

2006

Journal of Molecular Catalysis A: Chemical

193

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Section: Methodsmentioning

confidence: 97%

Enhanced photocatalytic activity of TiO2 by doping with Ag for degradation of 2,4,6-trichlorophenol in aqueous suspension

Selvaraj

2006

Journal of Molecular Catalysis A: Chemical

193

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“…In many cases, a gas stream, which also flows upwards, is applied. In the FR of Figure 2, Zhang et al 1994Sclafani et al 1993 Bellobono et al 1995Bellobono et al , 1997Bellobono et al , and 1998Gianturco and light is carried into the liquid by a large number of fibers. It is assumed that the light input is the same as that in the other designs.…”

Section: Photocatalytic Reactor Configurationsmentioning

confidence: 97%

Performance of immobilized photocatalytic reactors in continuous mode

et al. 2003

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) A packed-bed PBR , fiber FR , membrane MR , and tubular TR photocatalytic reactor ha®e been modeled to compare their performance on a pilot scale. The influence of radial dispersion in the PBR and mass-transfer limitation in the PBR, FR, and TR has been taken into account. The oxygen concentration in the liquid has a large influence on the performance and, therefore, air or pure oxygen should be added. The MR and PBR ha®e a better performance than the TR and FR. Only a small degree of mass-transfer limitation occurs in the PBR. Radial dispersion hardly influences the performance of the PBR. External mass-transfer limitation influences the con®ersion in the TR and FR se®erely. The PBR, MR, and TR show a much better energy efficiency than the FR. Introduction Ž. Like other advanced oxidation technologies AOTs , heterogeneous photocatalysis is an emerging technology for water purification. Almost any organic pollutant present in water can totally be degraded to carbon dioxide, water, and mineral acids. Heterogeneous photocatalysis for water purification is based on a semiconductor, usually TiO , and UV-A 2 Ž . radiation -385 nm . The light activates the semiconductor by generating electron᎐hole pairs. These charge carriers can participate in redox reactions at the surface and form hy-Ž droxyl radicals, which can degrade the pollutant Halmann, 1996;Hoffmann et al., 1995;Mills et al., 1997;Bahnemann, . 1999;Serpone and Pellizetti, 1989;Schiavello, 1997 . In the field of heterogeneous photocatalysis, much research has been performed on the laboratory scale, but no industrial application exists to our knowledge. One of the reasons that prevented this technology from being established in industrial installations is the absence of efficient re-Ž actors, proper reactor design, and reactor optimization Ollis et al., 1991;Legrini et al., 1993; Rajeshwar, 1995;Maurino et . al., 1999 . Reactors presented in the literature can be divided into two categories: reactors using solar light, and those using artificial light. The solar reactors will not be discussed, since our project focuses on reactors using artificial light. A sumCorrespondence concerning this article should be addressed to. M. F. J. Dijkstra. mary of the most important reactor designs in the artificiallight reactor category is given in Table 1. Ž Slurry reactors have often been investigated Cassano et . al., 1995 : in the laboratory, an immersed annular reactor is the type most used. A promising design is that using a thin flowing film of a titanium dioxide suspension over an illumi-Ž nated glass plate or annulus Ollis and Turchi, 1990;Yue, . 1997 . The cocurrent downflow contactor reactor has two sections. In the top part, the pollutants adsorb onto the catalyst; in the lower part the slurry is irradiated to degrade the Ž . pollutants Winterbottom et al., 1997 . Several designs are meant to enhance the mixing of the suspension so that all of Ž the catalyst can be illuminated for example, by using a rotat-. Ž ing glass tube Karpel Vel Leitner et al., 1996;Sczec...

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“…3. The XRD pattern of these samples showed the presence of three main peaks at 2 = 25.4 o (101), 37.8 o , and 48.1 o regarded as an attributive indication of anatase titania [18,19]. In addition to the characteristic peak of 101 plane, diffraction peaks corresponding to rutile titania also appeared on the pattern at 2 = 27.…”

Section: Characteristics Of Tio 2 and Ag-tio 2 Photocatalystsmentioning

confidence: 95%

Photocatalytic degradation of bisphenol A as an endocrine disruptor in aqueous suspension using Ag-TiO<SUB align=right>2 catalysts

Selvaraj

2006

IJEP

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A novel photocatalyst, titanium dioxide (TiO 2 ) deposited with silver (Ag), was prepared by a ultrasonic-assisted sol-gel method and studied for the photocatalytic degradation of endocrine disrupting chemicals such as Bisphenol A (BPA) under UV illumination, in order to determine its photocatalytic properties. A series of Ag-TiO 2 catalysts prepared with different Ag dosage were characterized by SEM, EDX, XRD, XPS, and UV-Visible absorption spectroscopy and their photocatalytic activity was evaluated in the degradation of BPA in aqueous suspension.The experiment demonstrated that the presence of Ag in TiO 2 catalysts could enhance the photocatalytic oxidation of BPA in aqueous suspension. It was found that the degradation of BPA by these catalysts followed the first-order kinetic model. The mechanism of the photocatalytic degradation of BPA in this study indicated that the nanosized Ag deposits on TiO 2 particles acted as the sites of electron accumulation where the reduction of adsorbed species such as oxygen occur. The enhanced reduction of oxygen through better electron-hole separation in Ag-TiO 2 particles compared to pure TiO 2 particles increased the rates of BPA degradation. In the reaction of BPA degradation, the presence of two methyl groups in the BPA structure were initially attacked with . OH and/or . OOH radicals which have strong oxidizing power, and then followed by the cleavage of the two phenyl moieties. Finally, the photomineralisation to CO 2 gas occurred via oxidative processes involving carboxylic acids and aldehydes. However, the photocatalytic remediation of contaminated water environments may present a potential risk of irregular and unanticipated reactions by active oxygen species during the photodecomposition, in which some intermediate products may be even more hazardous than the parent compounds [15][16]. In particular, TiO 2 photocatalysis in aqueous media probably yields a variety of intermediates in uncontrollable radical reactions. Therefore, a safe process of photocatalytic oxidation should not only examine the degradation of substrate compounds during the photoreaction, but also monitor the mineralization of the substrate organics as well.In the present study, a series of TiO 2 and Ag-TiO 2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their photocatalytic activity was evaluated in the photocatalytic degradation of BPA in aqueous suspension. Experimental MaterialsTetra-n-butyl titanate (Ti(O-Bu) 4 ) and silver nitrate (AgNO 3 ) with analytical grade were purchased from Aldrich Chemical Company., USA and used as titanium and silver sources for the preparation of TiO 2 and Ag/TiO 2 photocatalysts. BPA (2,2-bis(4-hydroxyphenyl) propane) with analytical grade was obtained also from Aldrich and used without further purification. The molecular structure of BPA is shown in Fig. 1. Deionized doubly-distilled water was used for the preparation of all solutions.[ Preparation of photocatalystsThe silver-deposited TiO 2 samples (Ag-TiO 2 ) were prepared b...

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Laboratory- and pilot-plant-scale photodegradation of chloroaliphatics in aqueous solution by photocatalytic membranes immobilizing titanium dioxide

Cited by 59 publications

References 11 publications

Enhanced photocatalytic activity of TiO2 by doping with Ag for degradation of 2,4,6-trichlorophenol in aqueous suspension

Enhanced photocatalytic activity of TiO2 by doping with Ag for degradation of 2,4,6-trichlorophenol in aqueous suspension

Performance of immobilized photocatalytic reactors in continuous mode

Photocatalytic degradation of bisphenol A as an endocrine disruptor in aqueous suspension using Ag-TiO<SUB align=right>2 catalysts

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