Establishing photon absorption fields in a Photo-CREC Water II Reactor using a CREC-spectroradiometric probe

Valadés-Pelayo, Patricio J.; Rio, Jesus Moreira del; Solano-Flores, Pastor; Serrano, Benito; Lasa, Hugo de

doi:10.1016/j.ces.2014.04.041

Cited by 24 publications

(25 citation statements)

References 39 publications

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“…By combining the solar radiation spectrum taken from [40] P25, with g = 0.68 [30] and 0.3 < g < 0.9 depending on wavelengths [17], which suggests that predominantly forward scattering with positives values of g (usually higher than 0.5) are more suitable for describing the scattering phenomenon of irradiated aqueous suspensions of titanium dioxide.…”

Section: Application Of Sfm-hg To Solar Heterogeneous Photocatalytic mentioning

confidence: 99%

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Acosta-Herazo

Monterroza-Romero

Mueses

et al. 2016

Chemical Engineering Journal

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Robust and practical models describing the radiation field in heterogeneous photocatalytic systems, used in emerging environmental, photochemical and renewable energy applications, are fundamental for the further development of these technologies. The sixflux radiation absorption-scattering model (SFM) has shown to be particularly suitable for the modeling of the radiation field in solar pilot-plant photoreactors. In this study, the SFM was coupled to the Henyey-Greenstein (HG) scattering phase function in order to assemble the model with a more accurate description of the scattering phenomenon provided by this IntroductionAs an emerging environmental technology, heterogeneous photocatalysis has received increasing attention in recent years. Its promising applications in air and water remediation[1], clean fuels production [2], green products (e.g. self-cleaning surface [3]) and selective 4 synthesis of organic molecules [4] demonstrates great interest in this technology. The underlying basis of every photocatalytic reaction mechanism is the photoactivation of the semiconductor photocatalyst by absorption of photons with energy higher or equal than the catalyst band-gap. The consequent generation of electron-hole pairs produces a chain of reactions that drive simultaneous oxidation and reduction (redox) reactions.The evaluation of the radiation field and of the spatial distribution of radiation absorption in a photoreactor system, commonly described by the local volumetric rate of photon absorption (LVRPA), is therefore a crucial aspect in the development of efficient photocatalytic processes [5].The LVRPA is the photon equivalent to the concentration of reactant species and is always considered in the description of the kinetics of photochemical reactions and in the optimization of the performance of photoreactors. For instance, several methodologies have been proposed for the determination of the optimum catalyst load or reactor thickness which maximize the absorption of radiation [6,7].The estimation of the LVRPA has been a defiant task within the heterogeneous photocatalysis community, as result of the complex nature of the absorption and scattering radiation phenomenon, which in the most rigorous case is modeled by the Radiative Transfer Equation (RTE). The RTE for a medium that does not emit radiation is [8]: where I λ is the photon irradiance at λ wavelength, s is a spatial coordinate, Ω is the directional solid angle, κ λ is the absorption coefficient and σ λ the scattering coefficient. TheΩ → Ω is the scattering phase function representing the probability of a photon to be redirected by scattering from the direction Ω', in surroundings of the position s, into the direction Ω [8]. A trivial solution for the RTE cannot be achieved and a numerical method is always necessary.Although the precise modeling of the LVRPA and a better understanding of the radiationphotocatalyst-operational conditions nexus still remains a challenge, several approaches have been proposed to solve the RTE. The most rigoro...

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Section: Application Of Sfm-hg To Solar Heterogeneous Photocatalytic mentioning

confidence: 99%

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Acosta-Herazo

Monterroza-Romero

Mueses

et al. 2016

Chemical Engineering Journal

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show abstract

“…Radiation absorption fields, for both reactors, were obtained from radiative models reported in recent contributions by our research group [35,36]. The Henyey-Greenstein (HG) phase function was used, as presented in the following equation:…”

Section: Radiative Modelsmentioning

confidence: 99%

“…When using the Degussa P25, Valades-Pelayo et al [35] determined that g ¼ 0:68 at a pH = 7. Given that the present degradations are to be carried out at a pH of 3.25 ± 0.05, this same methodology was used to determine a corrected scattering parameter that accounts for the pH change.…”

Section: Radiative Modelsmentioning

confidence: 99%

“…Furthermore, in this figure, the simulations for the optimized g ¼ 0:41 are presented. Additionally, for comparison purposes, data for a pH = 7, and the simulations with the g determined by Valades-Pelayo et al [35] are reported.…”

Section: Radiative Modelsmentioning

confidence: 99%

“…When solving the RTE, the LVREA is determined [34][35][36] regarded as a critical parameter for photocatalytic reaction engineering, being able to link radiation modelling with kinetic modelling [6]. Regarding the LVREA, the main parameters affecting it are: (i) the reactor geometry, (ii) the Nomenclature A parameter for free radical source term (m 3 g À1 s À1 ) B parameter for charge generation/recombination (mg lW À1 ) C cat photocatalyst concentration (mg l À1 ) C ox oxalic acid concentration (ppm of C) C f adsorbed free radical concentration per unit volume (mol m À3 ) D z axial dispersion coefficient (m 2 /s) E Einsteins (moles of photons s À1 ) ½e À electron surface concentration (mol e À m À2 ) g…”

Section: Introductionmentioning

confidence: 99%

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