Three-dimensional simulation of microcapillary and microchannel photo reactors for organic pollutant degradation from contaminated water using computational fluid dynamics

Document Type: Research Paper

Authors

Department of Chemical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran

Abstract

A three-dimensional (3D) simulation of four photocatalytic microreactors is performed using mass and momentum balance equations. The simulated results are validated with the available experimental data for the photocatalytic removal of methylene blue (MB) in two microcapillaries as well as dimethylformamide (DMF) and salicylic acid (SA) in two microchannels. In the surface layers of the microreactor, a photo removal reaction takes place, and the kinetic rates are described by the Langmuir-Hinshelwood (L-H) model. The Damköhler number for these microreactors is less than one, which indicates that the mass transfer rate is limited by the reaction rate. The numerical study and kinetic constants determination are carried out by using computational fluid dynamic techniques. The 3D modelpredictionsare ingood agreementwith the availableexperimental data sets. The results of the parametric study show that by increasing the microreactor length from 50 to 90mm, the removal efficiency improves from 76% to 93%. Moreover, the removal rate is increased by about 40% by reducing the microchannel depth from 500 to 100 .

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[1] Kaan, C. C., Aziz, A. A., Ibrahim, S., Matheswaran, M., Saravanan, P. (2012) “Heterogeneous photocatalitic oxidation an effective tool for wastewater treatment,” “In: Kumarasamy M., (Ed.), Studies on water management issues”, In Tech Pub., 219-274.
[2] Georges, R., Meyer, S., Kreisel, G. (2004). Photocatalysis in microreactors. Journal of photochemistry and photobiology A: chemistry, 167(2-3), 95–99.
[3] Padoin, N., Soares, C. (2017). An explicit correlation for optimal TiO2 film thickness in immobilized photocatalytic reaction systems. Chemical engineering journal, 310, 381–388.
[4] Zhang, Q., Zhang, Q., Wang, H., Li, Y. (2013). A high efficiency microreactor with Pt/ZnO nanorod arrays on the inner wall for photodegradation of phenol. Journal of hazardous materials, 254, 318–324.
[5] Van Grieken, R., Aguado, J., López-Muoz, M. J., Marugán, J. (2002). Synthesis of size-controlled silica-supported TiO2 photocatalysts. Journal of photochemistry and photobiology A: chemistry, 148, 315–322.
[6] Vaiano, V., Sacco, O., Sannino, D., Ciambelli, P., Longo, S., Venditto, V., Guerra, G. (2014). N-doped TiO2/s-PS aerogels for photocatalytic degradation of organic dyes in wastewater under visible light irradiation. Journal of chemical technology and biotechnology, 89, 1175–1181.
[7] Matsushita, Y., Ohba, N., Kumada, S., Sakeda, K., Suzuki, T., Ichimura, T. (2008). Photocatalytic reactions in microreactors. Chemical engineering journal, 135, S303–S308.
[8] Chen, H. Y., Zahraa, O., Bouchy, M., Thomas, F., Bottero, J. Y. (1994). Adsorption properties of TiO2 related to the photocatalytic degradation of organic contaminants in water. Journal of photochemistry and photobiology A: chemistry, 85, 179–186
[9] Ortiz-Gomez, A., Serrano-Rosales, B., Salaices, M., de Lasa, H. (2007). Photocatalytic oxidation of phenol: reaction network, kinetic modeling, and parameter estimation. Industrial and engineering chemistry research, 46, 7394–7409.
[10] Corbel, S., Charles, G., Becheikh, N., Roques-Carmes, T., Zahraa, O. (2012). Modelling and design of microchannel reactor for photocatalysis. Virtual and physical prototyping, 7, 203–209.
[11] Corbel, S., Becheikh, N., Roques-Carmes, T., Zahraa, O. (2014). Mass transfer measurements and modeling in a microchannel photocatalytic reactor. Chemical engineering research and design, 92(4), 657–662.
[12]. Nakamura, H., Li, X., Wang, H., Uehara, M., Miyazaki, M., Shimizu, H., Maeda, H. (2004). A simple method of self-assembled nano-particles deposition on the micro-capillary inner walls and the reactor application for photo-catalytic and enzyme reactions. Chemical engineering journal, 101, 261–268.
[13]. Mills, A., Wang, J., Ollis, D. F. (2006). Dependence of the kinetics of liquid-phase photocatalyzed reactions on oxygen concentration and light intensity. Journal of catalysis, 243, 1–6.
[14] Herrmann, J. M. (2010). Photocatalysis fundamentals revisited to avoid several misconceptions. Applied catalysis B: environmental, 99, 461–468.
[15] Furman, M., Corbel, S., Le Gall, H., Zahraa, O., Bouchy, M. (2007). Influence of the geometry of a monolithic support on the efficiency of photocatalyst for air cleaning. Chemical engineering science, 62, 5312–5316.
[16] Dionysiou, D. D., Suidan, M. T., Baudin, I., Laı̂né, J. M. (2002). Oxidation of organic contaminants in a rotating disk photocatalytic reactor: reaction kinetics in the liquid phase and the role of mass transfer based on the dimensionless Damköhler number. Applied catalysis B: environmental, 38, 1–16.
[17] Guarlno, G., Ortona, O., Sartorlo, R., Vltagllano, V. (1985). Diffusion, viscosity, and refractivity data on the systems dimethylformamide-water and N methylpyrrolidone-water at 5 ºC. Chemical engineering data, 30, 366–368.
[18] Resende, M., Vieira, P., Sousa Jr., R., Giordano, R., Giordano, R. (2004). Estimation of mass transfer parameters in a Taylor-Couette-Poiseuille heterogeneous reactor. Brazilian journal of chemical engineering, 21(2), 175–184.
[19] Commenge, J.M., Falk, L., Corriou, J.P., Matlosz, M. 2001. Microchannel reactors for kinetic measurement: influence of diffusion and dispersion on experimental accuracy. In Matlosz M., Ehrfeld, W., Baselt, J. P. (Eds.) Microreaction Technology-IMRET 5: Proc. 5th International Conference on Microreaction Technology, Springer, Berlin, 131–140.