Three-dimensional CFD modelling of a photocatalytic parallel-channel microreactor. (16th January 2021)

• Record Type: Journal Article
• Authors: Yusuf, Ahmed; Palmisano, Giovanni
• Is Part Of: Chemical engineering science. Volume 229(2021)
• Publication Date: 2021-01-16
• Subjects: Photocatalysis -- Microreactor -- Wastewater treatment -- 3D modelling -- CFD; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2020.116051
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: 3D CFD model incorporates total recirculation and single pass modes of operation. 3D CFD model predicts experimental data in a wide range of reactant concentrations. Kinetic constant from 2D is 17% overestimated compared to 3D result. 3D model appears to give more realistic estimation than the 2D. Abstract: This paper presents the estimation of adsorption rate and apparent kinetic rate constants for photodegradation of 4-nitrophenol in a recirculating and single-pass photocatalytic microreactor using simulated solar radiation. The effect of changing initial concentration ( Co ) of 4-nitrophenol in a recirculation mode was predicted by employing a dynamic transport model with kinetics (momentum and mole transports) using COMSOL Multiphysics. Adsorption and kinetic rate constants were estimated by fitting 3D model to experimental data. The estimated monolayer ( m ) and multilayer ( n ) adsorption–desorption rate constants were 1.77x10 4 m 3 mol -1 h −1 ( kads, m ), 0.0252 h −1 ( kdes, m ), 1.77x10 4 m 3 mol -1 h −1 ( kads, n ) and 0.0126 h −1 ( kdes, n ) respectively; and apparent kinetic constant ( kapp ) was 2.16 h −1 . Results from the single pass model showed that a rise in Co produces an increase in initial degradation rate. Moreover, decreasing flow rate ( Q ), increasing microchannel length ( L ) and decreasing microchannel height ( h ) boost the overall conversion of 4-nitrophenol in solution. This work demonstrates the promising application of microreactors in heterogeneous photocatalysis as tertiary stage technology for wastewater treatment, especially for the photodegradation of recalcitrant pollutant.