Experimental comparison of three reactor designs for photocatalytic water purification

Dijkstra, Marcel; Buwalda, H.; Jong, A.W.F. de; Michorius, A.; Winkelman, Jozef G. M.; Beenackers, A.A.C.M.

doi:10.1016/s0009-2509(00)00259-1

Cited by 126 publications

(70 citation statements)

References 36 publications

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“…Preliminary tests revealed that formic acid was not photodegraded by UV-A light alone. Formic acid was analyzed o ine (samples taken from supply vessel) with Capillary Electrophoresis as described elsewhere (Dijkstra et al, 2001). Oxygen was analyzed on-line with an INGOLD oxygen electrode in the supply vessel.…”

Section: Chemical Substancesmentioning

confidence: 99%

“…However, a major drawback of suspended systems in practical applications is the costly separation step necessary after the puriÿcation. Therefore, an immobilized system will be the preferred alternative for an e cient reactor scalable to industrial sizes, especially since the e ciency of the immobilized system can be comparable to that of the suspended system (Dijkstra et al, 2001). This study focuses on the photocatalytic degradation of a model component, formic acid, in an immobilized system.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the photocatalytic degradation of formic acid in a reactor with immobilized catalyst

Dijkstra

Panneman

Winkelman

et al. 2002

Chemical Engineering Science

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111

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A kinetic model for the photocatalytic degradation of formic acid in an immobilized system is presented, including the dependency of the reaction rate on the concentration of formic acid and oxygen, the catalyst layer thickness and the light ux. In the system some external mass transfer limitation occurs which is included in the modeling with experimentally determined values for the mass transfer coe cient of both formic acid and oxygen. The model describes the measurements well. The degradation rate appears to depend linearly on the light intensity. The adsorption of formic acid and oxygen on the catalyst layer appears to play an important role in the degradation rate. ?

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Section: Chemical Substancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling the photocatalytic degradation of formic acid in a reactor with immobilized catalyst

Dijkstra

Panneman

Winkelman

et al. 2002

Chemical Engineering Science

Self Cite

111

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“…stadler et al, 1994;Peill and Hoffmann, 1996 . In fluidizedand packed-bed photocatalytic reactors, a large specific area is created using titanium dioxide coated on silica-based carri-Ž ers or titanium dioxide pellets Dijkstra et al, 2001; Al-Ekabi and Serpone, 1988; Raupp et al, 1997;Zhang et al, 1994;Sclafani et al, 1993; Yamazali-Nishida et al, 1993;Starosud et al, 1999;Dibble and Raupp, 1992;Haarstrick et al, 1996; . Pozzo et al, 1999 .…”

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confidence: 99%

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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“…Various studies have identified the existence of mass transfer limitations in many immobilized systems, such as tubular reactors [7], [8], annular reactors [9]- [11], rotating disc reactors [9], [12], and packed-bed reactors [7], [13], among others [14]. A commonly used model equation derived from first principles is a Langmuir-type equation based on volumetric flowrate Q [15], [16]:…”

Section: Introductionmentioning

confidence: 99%

Design, Mass Transfer Studies, and Optimization of an Air-Sparged Tubular Photocatalytic Reactor for the Degradation of Methylene Blue

Dalida¹,

Ramoso²

2017

IJCEA

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Abstract-An alternative process for the removal of organic pollutants in aqueous systems is photocatalysis. The challenges hindering its industrial use are electron-hole recombination and mass transfer limitations. In order to address these problems, the objective of this study is to introduce air by sparging, and design an air-sparged photocatalytic reactor using titanium dioxide immobilized on borosilicate glass. The performance of the reactor on the removal of the model pollutant, methylene blue (MB), was evaluated and compared against the reactor operated without sparging. The effect of mass transfer limitations on reactor performance was also investigated by regression using a Langmuir-type model equation. Reactor performance was optimized using Response Surface Methodology to determine the set of initial MB concentration, treatment time, initial pH, and sparging rate that would result to the highest removal of methylene blue. The sparged photocatalytic reactor was able to degrade 57% MB in 2 hours, an improvement of 40% compared to no sparging. Mass transfer limitation studies showed that the reactor operates near the reaction-limited regime, and that the extent of mass transfer limitation effects was reduced. The set of parameters that maximizes methylene blue removal were 2.0 ppm MB, 120 minutes treatment time, pH 9.95 and 2.0 L/min sparging rate, with a predicted removal of 55.5%. Validation experiments resulted to 57.2% MB removal, and that the present reactor is comparable to similar reactors in literature, but with the advantage of using less expensive materials of construction and simpler immobilization technique.Index Terms-Photocatalysis, response surface methodology, tubular photocatalytic reactor, wastewater treatment.

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Experimental comparison of three reactor designs for photocatalytic water purification

Cited by 126 publications

References 36 publications

Modeling the photocatalytic degradation of formic acid in a reactor with immobilized catalyst

Modeling the photocatalytic degradation of formic acid in a reactor with immobilized catalyst

Performance of immobilized photocatalytic reactors in continuous mode

Design, Mass Transfer Studies, and Optimization of an Air-Sparged Tubular Photocatalytic Reactor for the Degradation of Methylene Blue

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