Document Type : Research Paper
Authors
Department of Chemical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran
Abstract
In photocatalytic microreactors the catalyst layer is obtained by integration of nanostructure films of semiconductors. One of these nanostructures that have a good photocatalytic activity is ZnO nanowires. The photocatalytic degradation of methylene blue in a continuous flow microreactor with ZnO nanowires deposited film is simulated. A finite element model is developed using COMSOL Multiphysics version 5.3 software to simulate the microreactor performance. The kinetic law of the photocatalytic reaction is assumed to be Langmuir–Hinshelwood. The kinetic constants kLHa and K are determined 1.43×10-7 mol/m2s and 7.5 m3/mol, respectively. The percent of average absolute deviation of the model in predicting the methylene blue outlet concentration obtained about 0.12% mol/m3. The model showed a very good agreement with the published experimental data. The effect of microreactor depth, methylene blue inlet concentration and flow rate on the methylene blue degradation is also investigated. The simulation results showed that the microreactor with shorter depth and lower values of inlet concentration and flow rate has higher efficiency. Thiele modulus and Damköhler number are both estimated lower than 1. It indicates that the photocatalytic reactions occur without internal and bulk mass transfer limitations.
Keywords
Charles G., Roques-Carmes T., Becheikh N., Falk L., Commenge J.M., Corbel S., Determination of kinetic constants of a photocatalytic reaction in microchannel reactors in the presence of mass-transfer limitation and axial dispersion, Journal of Photochemistry and Photobiology A: Chemistry 223 (2011) 202-211.
Corbel S., Becheikh N., Roques-Carmes T., Zahraa O., Mass transfer measurements and modeling in a microchannel photocatalytic reactor, Chemical Engineering Research and Design 92 (2014) 657-662.
Dijkstra M.F.J., Panneman H.J., Winkelman J.G.M., Kelly J.J., Beenackers A., Modeling the photocatalytic degradation of formic acid in a reactor with immobilized catalyst, Chemical Engineering Science 57 (2002) 4895-4907.
Gorges R., Meyer S., Kreisel G., Photocatalysis in microreactors, Journal of Photochemistry and Photobiology A: Chemistry 167 (2004) 95-99.
Han Zh., Li J., He W., Li S., Li Zh., Chu J., Chen Y., A microfluidic device with integrated ZnO nanowires for photodegradation studies of methylene blue under different conditions, Microelectronic Engineering 111 (2013) 199-203.
He Z., Li Y., Zhang Q., Wang H., Capillary microchannel based microreactors with highly durable ZnO/TiO2 nanorod arrays for rapid high efficiency and continues flow photocatalysis, Applied Catalysis B: Environmental 93 (2010) 376-382.
Helen L., Microfluidic reactors for photocatalytic water purification, Lab on a Chip, 14 (2014) 1074-1082.
Jayamohana H., Smith Y.R., Hansen L.C., Mohanty S.K., Gale B.K., Misra M., Anodized titania nanotube array microfluidic device for photocatalytic application: Experiment and simulation, Applied Catalysis B: Environmental 174-175 (2015) 167-175.
Jewell K.S., Falas P., Wick A., Joss A., Ternes T.A., Transformation of diclofenac in hybrid biofilm activated sludge processes, Water Research 105 (2016) 559-567.
Krivec M., Zagar K., Suhadolnik L., eh M., Drazi G., A highly efficient TiO2-based microreactor for photocatalytic applications, Applied Material Interfaces 5 (2013) 9088-9094.
Kuo T., Lin Ch., Kuo C., Huang M.H., Growth of ultralong ZnO nanowires on silicon substrates by vapor transport and their use as recyclable photocatalysts, Chemistry of Material 19 (2007) 5143-5147.
Lee K.M., Lai C.W., Koh S.N., Juan J.C., Recent developments of zinc oxide based photocatalyst in water treatment technology: A review, Water Research 88 (2016) 428-448.
Lei L., Wang N., Zhang X.M., Tai Q., Tsai D.P., Chan H.L.W., Optofluidic planar reactors for photocatalytic water treatment using solar energy, Biomicrofluidics 4 (2010) 1-12.
Liao W., Wang N., Wang T., Xu J., Han X., Liu Zh., Zhang X., Yu W., Biomimetic microchannels of planar reactors for optimized photocatalytic efficiency of water purification, Biomicrofluidics 10 (2016) 1-8.
Meng Z., and Zhang XQin., A high efficiency microfluidic-based photocatalytic microreactor using electrospun nanofibrous TiO2 as a photocatalyst, Nanoscale 5 (2013) 4687-4690.
Mills A., and Wang J.S., Photomineralisation of 4-chlorophenol sensitised by TiO2 thin films, Journal of Photochemistry & Photobiology. A Chemistry118 (1998) 53-63.
Ould-Mame S.M., Zahraa O., Bouchy M., Photocatalytic degradation of salicylic acid on fixed TiO2- kinetic studies, International Journal of Photoenergy 2 (2000) 59-66.
Ramos B., Ookawara S., Matsushita Y., Yoshikawa S., Low-cost polymeric photocatalytic microreactors: Catalyst deposition and performance for phenol degradation, Journal of Environmental Chemical Engineering 2 (2014) 1487-1494.
Wang Y., Ma J., Zhu J., Ye N., Zhang X., Huang, H., Multi-walled carbon nanotubes with selected properties for dynamic filtration of pharmaceuticals and personal care products, Water Research 92 (2016) 104-112.
Wang N., Zhang X., Chen B., Song W., Chan N.Y., Chan H.L., Microfluidic photo-electrocatalytic reactors for water purification with an integrated visible-light source, Lab on a Chip, 12 (2012) 3983-3990.
Yusuf A., Oladipo H., Yildiz Ozer L., Garlisi C., Loddo V., Abu-Zahra M. R.M., Palmisano G., Modelling of a recirculating photocatalytic microreactor implementing mesoporous N-TiO2 modified with graphene, Chemical Engineering Journal 391 (2020) 123574-1-33.
Zhang Q., Wang H., Li Y., A high efficiency microreactor with Pt/ZnO nanorod arrays on the inner wall for photodegradation of phenol, Journal of Hazardous Materials 15 (2013) 318-324.
)