OP-II-3

PP-II-32EFFICIENCY IN PHOTOCATALYTIC REACTORS:MODELING OF RADIATION ABSORBED BY THE CATALYSTJesus Moreira 1 , Benito Serrano 2 , Aaron Ortiz 1 , Hugo de Lasa 11 The University of Western Ontario, London, Ontario., Canada, jmoreira@uwo.ca2 Universidad Autónoma de Zacatecas, MexicoAbstractPhotocatalytic reactions are the result of the interaction of light with a solidsemiconductor generating e - /h + pairs which are responsible for the degradation oforganic and inorganic compounds [1]. Several efficiency definitions in photocatalyticreactors are found in the literature; in all cases, efficiency determination involves akey variable, the rate of photons absorbed by the photocatalyst, which is found fromthe local volumetric rate of energy absorption (LVREA). An accurate evaluation ofLVREA is fundamental in the design and rating of photoreactors, and its estimationinvolves the solution of the Radiative Transfer Equation (RTE). Stochastic methods,such as Monte Carlo method (MCM), can be implemented with advantage overdeterministic methods in finding the LVREA [2]. A macroscopic radiation balance(MRB) can be performed combining radiometric measurements with a radiationbalance to experimentally determine the radiation absorbed by the photocatalystinside the photoreactor [3]. In the present study, the LVREA for a photocatalyticreactor is simulated by using MCM for two TiO 2 catalysts (DP25 and Anatase). Theexperimental LVREA was found for DP25 and Anatase catalysts applying a MRB to acontrol volume in the photoreactor with boundaries containing the slurred TiO 2catalyst. In the simulations, the averaged absorption and scattering coefficients aswell as their spectral distribution were used. Other parameters were also considered:the probability of photon absorption by the catalyst and the probability of radiationabsorption by the internal Pyrex glass tube. The Henyey-Greenstein phase functionwas adopted to represent forward, isotropic and backward scattering modes. It wasalso assumed that the UV lamp reflects all the back-scattered photons by the slurredmedium. Comparison of light absorption and forward-scattering radiation fromexperimental MRB and MCM showed a good agreement when the spectraldistribution for the absorption and scattering coefficients were used (see Figure 1). Inall the simulations, isocratic scattering rendered better results when compared withexperimental values.390