Oxidative Photomineralization of Dichloroacetic Acid in an Externally-Irradiated Rectangular Bubble Tank Reactor: Computational Fluid Dynamics Modeling and Experimental Verification Studies

Abstract

The effect of antecedent factors on the performance of an aerated tank photoreactor containing externally irradiated suspended titania particles has been carried out using the oxidative photomineralisation of dichloroacetic acid (DCA) as the model reaction. The phase hold-up contours, velocity distribution profiles, and the spatial variation of the incident radiative flux as well as the local volumetric rate of photon absorption (LVPRA) inside the reactor were obtained from computational fluid dynamics (CFD) simulation based on the simultaneous solution of the Navier-Stokes equation (NSE) and radiation transport equation (RTE). The species modeling equation (SME) for the oxidative decomposition of DCA to HCl and CO 2 was then coupled to the NSE and RTE to determine the influence of catalyst loading, air superficial velocity, pollutant concentration, and radiation intensity on the reactor performance. The SME utilized the intrinsic kinetic expression provided by Zalazar et al. [Chem. Eng. Sci. 2005, 60, 5240-5254] with rate parameters secured from a preliminary fit of our experimental data. The good agreement between numerical results and empirical data for practically all predictor variables suggest that CFD modeling is a reliable and valid tool for the design and evaluation of the new photoreactor system and may in fact be used as a surrogate for subsequent optimization studies. Within the range of variables examined, it is evident that although reaction rate initially increased with air flow rate, a "plateau" was attained after about 30 L min -1 . The rate also exhibited a maximum at a catalyst loading of about 2.5 g L -1 while a characteristic Langmuirtype dependency on DCA concentration was observed. However, reaction rate varied only linearly with light intensity indicating the absence of deleterious hole-electron recombination at the relatively low values (20-80 W m -2 ) employed.

Ultraviolet germicidal irradiation (UVGI) for in-duct airborne bioaerosol disinfection: Review and analysis of design factors

“…In general, the radiative transfer equation (RTE), which considers varying isothermal conditions, such as absorption, reflection, and refraction, is established to compute the irradiance field of the duct. Commonly used models include the P1 model [ 71 ], surface-to-surface model (S2S) [ 72 ], and the discrete ordinates (DO) model [ 71 , [73] , [74] , [75] , [76] ]. As for airborne microorganism transport, CFD simulation with the discrete phase model (DPM), which solves the particle trajectory based on Newton's second law and accounts for gravity, drag force, and momentum coupling between the particle and the fluid, is commonly used [ 77 ].…”

Effective radiation field model to scattering – Absorption applied in heterogeneous photocatalytic reactors

“…Other approaches to the modeling of radiant fields in heterogeneous photocatalytic reactors deal with stochastic models, which are based on Monte Carlo simulation [37][38][39], or with the application of Computational Fluid Dynamics (CFD) [21,[40][41][42][43]. The latter based on the constitutive equations of continuous-medium mechanics.…”

Modeling, simulation, and optimization of advanced oxidation technologies for treatment of polymeric wastewater

“…Although there are some studies on the computational fluid dynamics (CFD) of AOTs which involves simultaneous modeling of chemical species mass transfer, rigorous kinetic pathway, and photon flux distribution (Alpert et al, 2010;Mohajerani et al, 2010;Santro et al, 2010;Trujillo et al, 2010;Duran et al, 2011;Vincent et al, 2011), there is still little information on the CFD modeling of photo-Fenton-like process. In photo-Fenton-like process unlike the photo Fenton process (UV/Fe 2+ /H 2 O 2 ), Fe 3+ is used along with the UV radiation and H 2 O 2 .…”