Experimental and theoretical coupled approaches for the analysis of radiative transfer in photoreactors containing particulate media: Case study of TiO2 powders for photocatalytic reactions

Continuous flow photocatalytic reactor using TiO2‐coated foams, modeling and experimental operating mode

“…This material crystalline phase composition is 85% anatase and 15% rutile. After removal of fines, particle size analysis performed by normalized Dynamic Light Scattering (DLS) using a Mastersizer 3000 device indicated a log‐normal distribution with a mean diameter of 41 μm and a standard deviation of 17 μm 46 . CTI‐ALSYS was engaged to deposit this powder onto alumina‐based cellular foams, also provided by this company.…”

“…The RTE can be solved only if these medium intrinsic characteristics, called radiative properties, are defined. Note that the RTE resolution leads to knowledge of the local radiative intensity I λ whose may be integrated to obtain interest quantities of interest such as the transmittance through the studied medium, the local available radiant energy fluxes at each wavelength G λ (W·m −2 ) (), and the local volumetric rate of radiant energy adsorbed LVREA λ ( x ) (W·m −3 ), the product of G λ ( x ) with the effective absorption coefficient k abs , λ (). The RTE solution can be approximated by simplified models such as a two‐flux model or a six‐flux model 51,52 in the case of a one‐dimensional the radiative transfer and if the scattering effect is moderate 46 . Since it is not the case, the RTE resolution can be accurately obtained using the stochastic Monte Carlo method 53,54 .…”

“…In such a case, the phase function is independent of the wavelength and is written as 59,60 : where θ represents the polar angle (rad). Changes in the specific absorption, scattering and extinction coefficients of the TiO 2 VP Aeroperl® powder (kg·m −2 ) as a function of wavelength were derived from the work of Ribeiro et al 46 They were determined numerically from the Lorenz Mie theory, by considering the refractive index and density of the anatase and rutile crystal phase mixture, as well as the particle size distribution of VP Aeroperl®. In parallel, the transmittance values of VP Aeroperl® suspensions at different concentrations were measured in a dedicated experiment.…”

“…It can be performed by various methods with different levels of accuracy and complexity, that is, the simplified two or six flux model, 42 the discrete ordinate method or the stochastic Monte Carlo method 43–45 . In this study, the stochastic Monte Carlo method, previously implemented by our group in modeling photoreactors containing particulate media, 46 is adapted to achieve the resolution of the RTE in the case of TiO 2 ‐coated foams, which are complex textured structures. The second step is the identification of empirical, semi‐empirical, or ideally intrinsic parameters required when formulating the degradation kinetics of a micro‐pollutant 47–49 .…”

Continuous degradation of micropollutants in real world treated wastewaters by photooxidation in dynamic conditions

“…This LED UV panel was set 2 cm from the PMMA surface. Irradiance was delivered in a very narrow spectrum centered around 365 nm (Ribeiro et al, 2021). After calibration with a MU-200 UV sensor (Apogee Instruments, Logan, UT, USA), radiant flux density at the reactor surface was controllable and adjustable between 5 and 85 W/m².…”