Influence of mass transfer and chemical reaction on ozonation of azo dyes

Choi, In Su; Wiesmann, Udo

doi:10.2166/wst.2004.0214

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…Recently Vaidya and Kenig (2007) have reviewed the kinetic data present in the literature concerning this system observing significant discrepancies between the kinetic rate constants. Neither an agreement between different authors is found for example in the study of the oxidation of textile azo dyes with the ozone, a system with evident applications in environmental engineering (Liakou et al, 1997; Wu and Wang, 2001; Sevimli and Kinaci, 2002; Sevimli and Sarikaya, 2002; Choi and Wiesmann, 2004; Gokcen and Ozbelge, 2005). In a significant number of papers related with this problem, the kinetic rate constants are reduced to apparent pseudo‐first order rate constants which are not useful for reactor design, scale‐up or control purposes.…”

Section: Introductionmentioning

confidence: 95%

On bubble column reactor design for the determination of kinetic rate constants in gas–liquid systems

et al. 2010

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The design of a semibatch bubble column reactor with its mathematical description is proposed for the study of ozonation reactions. The mathematical model used to describe the gas-liquid mass transfer rate in the reactor is based on the unstationary film theory and the resulting model is theoretically analysed to identify its relevant parameters. After its structural identifiability analysis, the parameters are reduced to five, that is, the gas hold-up, the ratio of diffusivities of the reacting species, the volumetric mass transfer coefficient and two time constants related with the kinetic rate constant. From the sensitivity analysis of this reduced model, we conclude that it is not sensible to the gas hold-up and the diffusivity ratio of the reacting species for optimization purposes in moderate and slow kinetic regimes. The model is tested with the reaction between the ozone and the azo-compound Acid Red 27. The experimental data match quite well the model allowing the estimation of the volumetric mass transfer coefficient together with the kinetic constant. The kinetic rate constant for the direct reaction between the ozone and the Acid Red 27 is estimated in k 2 = 3723 ± 127 M −1 s −1 at 21.2 ± 0.5 • C. The self-coherence of the model, the absence of hypothesis about the state of the film together with the proposed optimization procedure, allows to consider the proposed methodology as a viable alternative for the study of gas-liquid systems in semi-batch bubble columns reactors in comparison with classical approaches.La conception d'un réacteur semi-continu de type colonneà bulles avec sa description mathématique est proposée pour l'étude des réactions d'ozonation. Le modèle mathématique utilisé pour décrire le taux de transfert de masse gaz-iquide dans le réacteur est fondé sur la théorie des pellicules en régime instationnaire et une analyse théorique du modèle en résultant est faite pour identifier ses paramètres pertinents. Après l'analyse d'identifiabilité structurale, les paramètres sont réduitsà cinq, c.-à-d., la retenue de gaz, le rapport de diffusivité des espèces en réaction, le coefficient volumétrique de transfert de masse et deux constantes de temps liéesà la constante du taux cinétique.À partir de l'analyse de sensibilité de ce modèle réduit, nous concluons qu'il n'est pas sensibleà la retenue de gaz et au rapport de diffusivité des espèces de réaction pour les besoins d'optimisation. Le modèle est examiné par rapportà la réaction entre l'ozone et l'azocomposé acide rouge 27. Les données expérimentales s'accordent toutà fait au modèle permettant l'estimation du coefficient volumétrique de transfert de masse ainsi que de la constante cinétique. La constante de taux cinétique pour la réaction directe entre l'ozone et l'acide rouge 27 est estiméà k2 = 3723 ± 127 1/(M.s)à 21,2 ± 0,5 • C. L'auto-cohérence du modèle, l'absence d'hypothèse relativeà l'état de la pellicule, ainsi que le processus d'optimisation proposé, nous permettent de considérer la méthodologie proposée comme une alternative viab...

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Section: Introductionmentioning

confidence: 95%

On bubble column reactor design for the determination of kinetic rate constants in gas–liquid systems

et al. 2010

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“…For low dye concentrations, the mass transfer alone was decisive for the reaction rate showing no enhancement due to chemical reaction. However, in the region of high dye concentrations, the slope of the ozone concentration profile inside the liquid boundary layer increased with increasing dye concentrations as a result of a chemical oxidation (Choi and Wiesmann, 2004 (Neamţu, et al, 2004b).…”

Section: Advanced Oxidationmentioning

confidence: 98%

Textiles

Chiavola¹

2005

Water Environment Research

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“…Liao et al [27] reported that dye solutions exposed to UV radiation only, achieved varying decolorization depending upon type of dye as well as UV intensities and contact time. Therefore, the UV degradation processes must be accompanied with oxidants/photocatalysts such as H 2 O 2 , TiO 2 or ozone to generate active hydroxyl radicals to initiate autooxidation reactions for complete degradation [28,29] . According to Feng et al [25] , addition of chemicals as oxidants could interfere with the process and thus recommended the application of dielectric barrier discharge (DBD) driven excimer lamps.…”

Section: −2mentioning

confidence: 99%

Treatment of Remazol Brilliant Blue Dye Effluent by Advanced Photo Oxidation Process in TiO2/UV and H2O2/UV reactors

Verma¹,

Ghaly²

2008

American J. of Engineering and Applied Sciences

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Advanced oxidation processes involving TiO 2 /UV and H 2 O 2 /UV were evaluated for their potential use in decolorization of textile dye effluents. A coil photo reactor, consisting of UV radiation source and a spiral coil coated with TiO 2, was used to treat synthetic effluent of Remazol Brilliant Blue dye. The TiO 2 coating was performed using the sol-gel technique. The effects of UV radiation, TiO 2 coatings and dye concentration were studied and the results were compared to dye treatment involving H 2 O 2 . The maximum dye removal efficiencies were 7.3, 12.2 and 12.5 % for uncoated, single coat and dual coat of TiO 2 , respectively. The decolorization efficiency was inversely related to dye concentration of the effluent. The treatments with UV only, TiO 2 only, UV+TiO 2 , H 2 O 2 only and UV+H 2 O 2 resulted in color reduction of 7.6, 2.3, 12.5, 4.1 and 99.9 % respectively. The maximum decolorization occurred in ≤ 100 min in all cases. The temperature varied from 29.2 to 54.7°C for UV+TiO 2 treatment and no change in reactor temperature was observed when UV was not used.

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Influence of mass transfer and chemical reaction on ozonation of azo dyes

Cited by 8 publications

References 6 publications

On bubble column reactor design for the determination of kinetic rate constants in gas–liquid systems

On bubble column reactor design for the determination of kinetic rate constants in gas–liquid systems

Textiles

Treatment of Remazol Brilliant Blue Dye Effluent by Advanced Photo Oxidation Process in TiO2/UV and H2O2/UV reactors

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