| A concentric annular slurry photoreactor was designed, in this study, to investigate the near UV light transmission throughout photocatalyst suspensions and to evaluate the operational conditions that enhance the photodegradation energy efficiency. Experiments were developed with seven TiO 2 commercial powders having differences in particle size, agglomerate particle size in water suspension, and specific surface area. Black collimators and inner polished aluminum collimators were attached to several equidistant axial windows to measure the total transmitted radiation and the transmitted non-scattered radiation through several catalyst concentrations. This method, and the use of a macroscopic radiation balance allowed for the estimation of the radiation absorption and of the extinction coefficients of the dispersed medium.; In this respect, the radiation modeling of the present study permits to establish that the forward transmitted radiation can be represented by the difference of two relatively simple exponential decay functions accounting respectively for the total transmitted radiation and the transmitted nonscattered radiation. These two exponential are function of particle concentration and extinction coefficients, with these extinction coefficients being strongly affected by the particle agglomerate size and radiation wavelength.; The photoconversion of phenol and methylene blue as model pollutants allowed assessment of the rate of photodegradation of molecules and the effect of several operating parameters including the addition of adsorbent materials, on both the photo degradation reaction rate and the process efficiency.; In the case of the phenol photodegradation, it was found that the rate of phenol consumption can be linked to the catalyst concentration, following similar exponential functions as the ones found using independent transmission experiments.; Regarding the mechanism of phenol photoconversion and on the basis of identified and quantified intermediate species, a series-parallel model was postulated. It is shown that this model appears to be adequate in describing the experimental results and that the parameters resulting from this model can be estimated with reduced spans and adequate reliability. |
