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An integral reactor design methodology was developed to address the optimal design of photocatalytic wall reactors to be used in air pollution control. For a target pollutant to be eliminated from an air stream, the proposed methodology is initiated with a mechanistic derived reaction rate. The determination of intrinsic kinetic parameters is associated with the use of a simple geometry laboratory scale reactor, operation under kinetic control and a uniform incident radiation flux, which allows computing the local superficial rate of photon absorption. Thus, a simple model can describe the mass balance and a solution may be obtained. The kinetic parameters may be estimated by the combination of the mathematical model and the experimental results. The validated intrinsic kinetics obtained may be directly used in the scaling-up of any reactor configuration and size. The bench scale reactor may require the use of complex computational software to obtain the fields of velocity, radiation absorption and species concentration. The complete methodology was successfully applied to the elimination of airborne formaldehyde. The kinetic parameters were determined in a flat plate reactor, whilst a bench scale corrugated wall reactor was used to illustrate the scaling-up methodology. In addition, an optimal folding angle of the corrugated reactor was found using computational fluid dynamics tools. [ABSTRACT FROM AUTHOR]

The optimization of a corrugatedwall photocatalytic reactor forair treatment was addressed using the concept of efficiencies in series.A new concept has been introduced: the inner incidence efficiency,associated with the internal configuration of the reactor (for instance,the folding angle in the considered case). The goal of the study wasto obtain an optimum for the folding angle, subjected to certain constraints:fixed reactor volume, radiation flux, and gas flow rate. Previousexperimentally determined degradation kinetics of a gaseous pollutantwas used in the reactor modeling. The simulations of the reactor wereperformed computationally by using a computational fluid dynamics(CFD) package. The results showed opposed behaviors for the relativecatalytic area per unit window area and the relative incident fluxwith the folding angle. Given that the inner incidence efficiencycomprises the product of the two mentioned variables, an optimal foldingangle was identified. [ABSTRACT FROM AUTHOR]

Abstract: A methodology for modeling photocatalytic reactors for their application in indoor air pollution control is carried out. The methodology implies, firstly, the determination of intrinsic reaction kinetics for the removal of formaldehyde. This is achieved by means of a simple geometry, continuous reactor operating under kinetic control regime and steady state. The kinetic parameters were estimated from experimental data by means of a nonlinear optimization algorithm. The second step was the application of the obtained kinetic parameters to a very different photoreactor configuration. In this case, the reactor is a corrugated wall type using nanosize TiO2 as catalyst irradiated by UV lamps that provided a spatially uniform radiation field. The radiative transfer within the reactor was modeled through a superficial emission model for the lamps, the ray tracing method and the computation of view factors. The velocity and concentration fields were evaluated by means of a commercial CFD tool (Fluent 12) where the radiation model was introduced externally. The results of the model were compared experimentally in a corrugated wall, bench scale reactor constructed in the laboratory. The overall pollutant conversion showed good agreement between model predictions and experiments, with a root mean square error less than 4%. [Copyright &y& Elsevier]

Heterogeneous photocatalysis is a suitable technology for eliminating indoor pollutants at low concentration ranges. In this work we deal with the modeling and experimental evaluation of a continuous, single-pass, corrugated plate photocatalytic reactor for elimination of gaseous formaldehyde in air. The reactor configuration consists of a corrugated stainless steel plate coated with titanium dioxide catalyst, irradiated from both sides with UV lamps. The complete modeling of the reactor was achieved by means of a commercial CFD tool. Nonetheless, the radiative transfer within the reactor was modeled externally, considering the lamps emission and the radiative interaction between reactor windows and catalytic walls by the computation of view factors. The reaction kinetics was also imposed externally from previous determined parameters. The conditions of the experimental runs were replicated in the computational simulations. Model predictions of the formaldehyde overall conversion showed good agreement with experiments, with a root-mean-square error less than 4%. [ABSTRACT FROM AUTHOR]

Abstract: In the present work the existence of mass transfer limitations in slurry, photocatalytic reactors is studied. Experimental validation is made in a flat plate reactor that is part of a recycling system. The reactor is described with a mathematical model previously developed [. Chemical Engineering Journal 136, 50], considering a transient, two-dimensional mass balance (TDM). The complete reactor model was developed to show the existence of these effects, which result from the occurrence of concentration gradients in reaction space. They develop when these reactors are operated under some operating conditions whose effects should be always analyzed before assuming the validity of existence of perfect mixing in reaction space. Dichloroacetic acid (DCA) was the adopted model compound. To solve TDM, a kinetic expression for DCA acid was determined before under well mixed conditions [. Industrial and Engineering Chemistry Research 48(4), 1847]. The studied variables are flow rate, catalyst loading, and irradiation rates. The experimental data agree quite well when they are interpreted in terms of the two-dimensional model (TDM) regardless of the operating mode. The perfect mixing model (PMM), normally employed to describe this and other types of slurry photoreactors, does not have the same level of universal application; i.e. it is restricted to perfect mixing, but in many cases far simpler to use. However, it can be concluded that when the photocatalytic reaction is not fast, employing catalyst loadings below 1gL–1, irradiation rates at the reactor wall below 1×10−6 Einstein cm−2 s−1 and good mixing operation (Re>1700) it will be always safe to assume that mass transport limitations in the bulk of the fluid are nonexistent. In a typical batch reactor the above flow conditions are equivalent to very intense mixing. If the catalyst concentration is increased, the mixing conditions should be improved in the same proportion. Within limits, higher solid loadings can be compensated with lower irradiation rates [. Chemical Engineering Journal 136, 50]. In addition, with the validated model, additional simulations are shown, operating the reactor under different virtual reactor thicknesses to widen amplitude of the reached conclusions. These findings will be useful in kinetic studies to prevent incursion in certain ranges of experimental conditions that could lead to erroneous interpretation of the obtained kinetic data. [Copyright &y& Elsevier]

In the present work the degradation of 2-chlorophenol (2-CP) used as model compound, applying the Heterogeneous photo-Fenton reaction, was studied. Small particles of goethite or iron oxyhydroxide were used as a source of iron. The influence of catalyst loading, radiation intensity and the molar ratio between hydrogen peroxide and contaminant were examined. Improvement by illumination is highly significant. During the progress of 2-CP degradation, the reaction shows an unusual acceleration. This autocatalytic comportment, with stronger tendencies at higher temperatures, implies a completely different behaviour from the one typically expected. The autocatalytic performance is successfully explained by the joint action of two factors: (i) the evolution of the available iron in the homogeneous phase during the course of the reaction and (ii) the autocatalytic contribution of some of the reaction intermediates in the iron cycle. The small iron concentration leaching into the solution is produced by two typical liquid medium - solid goethite surface dissolution processes. A reaction mechanism has been proposed and, in a first stage, parameters have been obtained for the dark reaction. In a second step, the complete data for the irradiated operation were obtained. [ABSTRACT FROM AUTHOR]

Abstract: A study has been conducted on the decomposition of 2-chlorophenol (2-CP) applying a heterogeneous Fenton reaction using goethite as catalyst at pH 3. The research was aimed at obtaining a workable kinetic expression apt for developing a kinetic model for scaling up purposes. Several aspects of the reaction have been described in the available literature but, for the moment, without a reasonable representation of the entire reaction behavior. In order to provide a more comprehensive and probable explanation of the whole observed performance, a set of experiments was carried out varying systematically all the significant variables. The proposal considers that the reaction is essentially a combination of four heterogeneous processes associated with one typical homogeneous Fenton reaction. Three of the surface reactions explain a very small iron leaching to the medium by a proton induced solubilization, a reductive dissolution reaction and a non-reductive iron release produced by detected 2-CP chemical decomposition byproducts, particularly, chlorohydroquinone (ClHQ) and oxalic acid (OxA). Iron concentration in the solution may be further increased in the final stages of the reaction after most of the 2-CP has been degraded, by the appearance of OxA that takes part in a third surface reaction. The fourth heterogeneous reaction rationalizes the unusual hydrogen peroxide consumption at high catalyst loadings. During the homogeneous reaction, the presence of ClHQ and ClBQ produces a homogeneous autocatalytic beneficial enhancement of the Fe3+ →Fe2+ transformation. Consequently, the existence of phenolic derivatives either in the mixture or as reaction byproducts produces a beneficial enhancement of the reaction rate. Very low iron leaching is required to produce the onset of the homogeneous Fenton reaction, which was shown to be strongly dependent upon the reaction temperature. All the experimental findings were satisfactorily described by a set of 19-step feasible reaction scheme. The process could be useful for the treatment of wastewaters containing pollutants with phenolic derivatives, as long as iron leaching remains within tolerable limits. [Copyright &y& Elsevier]

Abstract: The kinetics of the degradation of 2-chlorophenol (2-CP) employing both the heterogeneous Fenton and photo-Fenton reactions using goethite as the solid catalyst is studied. The photoreactor was irradiated with a 350–400nm wavelength light. The kinetics is based on 19 steps of a combined heterogeneous–homogeneous mechanism derived for the thermal Fenton reaction [see companion article by the authors: Ortiz de la Plata et al. (2009)] . For the photo-Fenton alternative, two more steps are needed. Some of the specific kinetic constants of the reaction scheme are approximately known. However, for the heterogeneous “thermal” Fenton reaction, three new unknown constants were required and were attained from experimental data obtained in this and the previous work. The parameters were (i) the reaction of the HOwith 2-CP, (ii) the proton induced iron dissolution and (iii) the reductive induced iron dissolution . In the case of the heterogeneous photo-Fenton reaction steps, the radiation field in the reacting system was described by solving the complete radiative transfer equation inside the reactor. With this purpose, the knowledge of the needed goethite optical properties were previously characterized . Combining the dark and the irradiated experiments 21 kinetically consistent parameters were achieved for the proposal of a feasible mechanism. They are valid for both systems; making the two primary quantum yields of the photoreaction equal to zero, the “dark” Fenton reaction performance is properly described by the remaining 19 specific rate constants. These results are independent of the used experimental apparatus and can be safely used for scaling-up purposes within the range of the explored variables. [Copyright &y& Elsevier]

Abstract: Optical properties of solid catalysts needed for a rigorous modeling of heterogeneous photo-Fenton reaction kinetics and the ultimate reactor design have not been studied so far. Without these data, quantitative information concerning the influence of the radiation field in the process performance is almost impossible. These reactions are still under the first stages of their studies, and most of the effort has been aimed at elucidate yields, tentative mechanisms, the optimum operating pH and ways to reduce iron ions leaching to the aqueous solution. This work reports the values of above-mentioned parameters precisely calculated, resorting to specially designed spectrophotometer measurements coupled with the solution of the radiative transfer equation (RTE). Goethite, a natural occurring ferric oxide, was studied to obtain the values of the radiation linear volumetric absorption and scattering coefficients, as well as the phase function for scattering, some of them as a function of mass composition, and all of them as a function of the wavelength range between 310 and 500nm. The results indicate that, in addition to its demonstrated ability to degrade effectively many contaminants, its optical properties exhibit very low absorption and scattering properties. This outcome improves its potentiality for applications in large-scale reactors, because the resulting useful optical path length will be significantly large. Specifically, these results are compared with a typical photocatalytic substance, such as titanium dioxide to remark the differences. [Copyright &y& Elsevier]

The fungicide effect employing Aspergillus niger as a representative microorganism was tested applying a Photocatalytic paint formulated with an anatase carbon doped TiO 2 and compared with a homemade non-active paint (rutile TiO 2 ), a commercial normal indoor latex paint and a commercial “antifungal” latex paint. For this purpose Aspergillus niger conidia inactivation on the paints coatings was performed under visible and UV radiation applying different experimental conditions (relative humidity, radiation flux and absence of light). Under visible light no significant difference in conidia inactivation was found for all studied paints. Nevertheless, the Photocatalytic paint under UV radiation presented around 1.4 times higher fungus inactivation than the blank control paints. In order to evaluate the damage produced by visible or UV radiation over the conidia and to analyze the ability of repairing it, incubation at optimal germination conditions of Photocatalytic and normal paints after irradiation treatment was performed. For conidia irradiated on Photocatalytic paint, not only conidia could not germinate but also the inactivation continued even after the end of the irradiation assay. Finally, A. niger conidia was exposed over a culture medium with or without the paints pigments (Carbon doped TiO 2 or Rutile) under different types of radiation (visible and UV). Much greater growth control of vegetative forms was obtained by applying photocatalytic TiO 2 under both types of light. It can be concluded that the developed Photocatalytic paint presents a higher ability to control fungal growth compared to the other paints studied and could be applied for indoor air decontamination. Also, it was possible to control the dissemination agent that can generate more mold growth on surfaces and affect the people health. [ABSTRACT FROM AUTHOR]

A theoretical and experimental study of the photo-Fenton degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in water is presented. A kinetic model derived from a reaction sequence is proposed using the ferrioxalate complex as iron source for conditions of pH = 5. The kinetic model was employed to predict the concentrations of 2,4-D, 2,4-dichlorophenol (2,4-DCP), hydrogen peroxide (HP) and oxalate (Ox) in a flat plate laboratory reactor irradiated with a solar simulator. Two types of incident irradiation levels were tested by different combinations of attenuation filters. The effects of the oxalate/Fe +3 molar ratio (Ox/Fe), the reaction temperature ( T ) and the 2,4-D/HP molar ratio ( R ) on the photo-Fenton process were also investigated. For low radiation level and operating conditions of R = 50 and T = 50 °C, a 2,4-D conversion of 95.6% was obtained after 180 min. Moreover, the 2,4-D conversion was almost 100% in only 120 min when the system was operated under the same operating conditions and high radiation level. From the proposed model and the experimental data, the corresponding kinetic parameters were estimated applying a nonlinear regression method. A good agreement between the kinetic model and experimental data, for a wide range of simulated solar operating conditions, was observed. For 2,4-D, 2,4-DCP, HP and Ox concentrations, the calculated RMSE were 1.21 × 10 −2 , 5.45 × 10 −3 , 2.86 × 10 −1 and 2.65 × 10 −2 mM, respectively. [ABSTRACT FROM AUTHOR]

Pure (TiO2) and 0.1 nominal atomic percent of palladium-modified TiO2 (Pd-TiO2) films were synthesized via a sol–gel method and compared through their physicochemical properties and photocatalytic activity in the degradation of an emerging contaminant, 17-α-ethinylestradiol (EE2). The activity of the films was studied using a continuous flow, planar microreactor under simulated sunlight. Catalysts characterization included X-ray diffraction, UV–Visible diffuse reflectance and transmittance spectroscopy, atomic force microscopy, transmission electron microscopy, Raman spectroscopy, N2 physisorption analysis, and X-ray photoelectron spectroscopy. The modification of TiO2 with palladium confined the size of anatase phase crystallites, increased the specific surface area and improved radiation absorption. PdO domains on TiO2 were observed. In all the tested conditions, higher conversion of EE2 was achieved with the Pd-TiO2 film compared with the TiO2 film, presenting an 80% increase in the reaction rate. The performance of the catalytic films was also assessed by the calculation of two efficiency parameters: radiation absorption efficiency and quantum efficiency of reaction. The Pd-TiO2 film showed a notable enhancement of the absorption of the incident radiation and a more efficient utilization of the absorbed photons to degrade the target pollutant. [ABSTRACT FROM AUTHOR]

A theoretical and experimental study of a new pilot-plant solar reactor for the photo-Fenton treatment of waters containing toxic organic compounds is presented. This hybrid unit was designed and built to capture thermal and photochemical solar radiation, yielding higher degradation rates of a model pollutant. The mass and thermal energy balances and the radiative transfer equation are solved to compute the pollutant and hydrogen peroxide concentrations and the reaction temperature as a function of time. The spectral UV/visible and broadband solar radiation incident on the reactor window are estimated from a computational code: the Simple Model for the Atmospheric Radiative Transfer of Sunshine (SMARTS2) program. Under irradiated runs, an experimental temperature increase up to 25 °C is reached. Also, for a reaction time of 180 min and a relatively low iron concentration, the combined effect of UV/visible and thermal sunlight is able to degrade 98.2% of the initial pollutant concentration. [ABSTRACT FROM AUTHOR]

Abstract: This study is focused on the kinetic modelling of the Fenton and photo-Fenton degradation of a model pollutant (formic acid) in aqueous solution, for relatively low iron concentrations (1–9ppm). The reaction rate expressions are derived from an accepted reaction mechanism and explicitly having into account the local volumetric rate of photon absorption. The experimental work was performed in a well-stirred tank laboratory reactor irradiated from the bottom. Afterward, the proposed kinetic model and the experimental data were used to estimate the Arrhenius parameters between 20 and 55°C, applying a non-linear regression procedure. To avoid the precipitation of iron compounds during the experimental runs, simultaneous high reaction temperatures (55°C) and iron concentrations (9ppm) were prevented. To achieve this goal, an experimental design based on the D-optimality criterion was adopted. The proposed kinetic model was able to reproduce the combined effects of changing the ferric iron concentrations, reaction temperatures, and formic acid to hydrogen peroxide molar ratios on the pollutant degradation rate. Kinetic model predictions are compared with experimental data of the organic compound conversion, and a good agreement is obtained. For the whole set of Fenton and photo-Fenton experimental runs, the maximum root mean square error is 7.64%. [Copyright &y& Elsevier]

Abstract: A proposal for scaling-up photocatalytic reactors is described and applied to catalytic walls coated with a thin layer of titanium dioxide and irradiated with near UV radiation. The method is exclusively based on the fundamentals of chemical reaction engineering and radiative transfer theory, without the use of adjustable parameters in going from the laboratory information to a pilot scale apparatus. Mathematical modeling has been utilized. From kinetic information obtained in experiments performed in a flat plate of , operating at steady state in a continuous, well-mixed reactor with recycle, predictions for a continuous flow, multi-annular reactor having a catalytic surface of agree very well with the validation tests. Thus, the achieved scale-up implies a change in size, shape, configuration and operating conditions of both employed reactors. Requirements to apply satisfactorily the proposed methodology are reported in detail. The root mean square error in the verification of conversion predictions for the larger scale photocatalytic reactor when compared with experimental data is less than 5.6%. [Copyright &y& Elsevier]

This work describes the use of solar radiation to destroy an organic pollutant in aqueous solution, using the photo-Fenton reaction. Formic acid was chosen as the model substrate. A kinetic model that accounts for the dark (Fenton) and the light activated (photo-Fenton) reaction rates in a single mathematical expression has been used. Furthermore, to take into account the irradiated and the nonirradiated liquid volumes, a rigorous mass balance for each one of the reactant species has been applied. Under the adopted operating conditions, an organic pollutant conversion up to 81% was achieved after 1 h of operation. Predictions of the theoretical model were compared with experimental results and good agreement for formic acid and hydrogen peroxide concentration evolutions was obtained. Deviations between model predictions and experimental data were always smaller than 9%. Theoretical and experimental results of the pollutant conversion showed that solar irradiation improves the effectiveness of the Fenton system significantly; a pollutant conversion 175% greater than that obtained with the dark system alone was observed. [Copyright &y& Elsevier]

Photocatalysis in slurry reactors have the particular characteristic that the reacting medium not only absorbs but also scatters photons and both phenomena occurs simultaneously. When this is the case, typical methods used in classical photochemistry such as homogeneous actinometry are useless because they cannot take into account radiation scattering. Consequently present methods in use always underestimate quantum yields calculations. A method has been developed to produce absolute values of photocatalytic quantum yields in slurry reacting systems employing titanium dioxide and near UV radiation. The new procedure resorts to the rigorous solution of the radiative transfer equation inside the reaction space in order to obtain the true value of the photonic absorption rate. Employing monochromatic light, values for the photocatalytic decomposition of phenol and 1,4-dioxane are reported under precisely defined conditions. The method can be used to compare reactivities of different catalysts or, for a given catalyst, reactivities with different compounds regardless the reactor shape, size or configuration. [Copyright &y& Elsevier]

The kinetics of the photocatalytic decomposition of low concentrations of trichloroethylene (TCE) in water was modeled and the reaction parameters have been evaluated for different catalyst loadings. The employed reactor is a flat plate configuration irradiated by tubular lamps that have emission in the 300–400 nm wavelength range.The mass conservation model is two-dimensional while the developed radiation model is two-dimensional in space and two directional in radiation propagation. The performance of the photoreactor with this reaction can be properly represented employing only two lumped kinetic constants that can be derived from a 12 steps, complete reaction sequence. The deduced kinetic model has explicit functional dependencies for the local volumetric rate of photon absorption (LVRPA) and the effect of the catalyst concentration: rTCE,het(x¯,t)av=−SgCm,catα∫lower limit λ eλa(x¯,t,Cm,cat) dλ[α3CTCE/(1+α3CTCE)]. Values of the kinetic constants are: α=1.94×10−9 mol g1/2 cm−2 s−1/2 einstein−1/2 and α3=5.52×106 cm3 mol−1. As derived from the reaction sequence and validated with experiments, it was observed that the reaction rate is proportional to the square root of the LVRPA. The dependence on the catalyst loading, well described by the model, is more complex due to its characteristic effect on the light distribution inside the reaction space. [Copyright &y& Elsevier]

• PCT was completely removed with a ferrioxalate photo-Fenton reaction at pH = 5.5. • A D-optimal design with RSM is proposed to define optimal reaction conditions. • Level of irradiation resulted to be the most important operating parameter. • Toxicity levels are closely related to the presence of toxic reaction intermediates. • Complete removal of toxicity is achieved after 4 h of high irradiation conditions. This study discusses the degradation of paracetamol (PCT) by Fenton and photo-Fenton reactions at circumneutral pH with the aid of ferrioxalate and a solar simulator as the light source. The influence of three main operating variables: H 2 O 2 concentration (HP), temperature (T) and radiation level (Rad) on PCT conversion was evaluated with a D-optimal design and a response surface methodology (RSM). The analysis of variance (ANOVA) revealed that Rad and T significantly affected the studied response. The model performance was satisfactory, giving low standard deviation (0.74) and good R 2 and adjusted R 2 values (0.9997 and 0.9993, respectively). The optimal conditions found for each radiation level were tested. The obtained PCT conversions after 90 min of reaction (75.52 %, 96.88 % and 91.50 %, respectively) were in good agreement with the predicted values (71.28 %, 96.75 % and 92.75 %, respectively). It was observed that the maximum and minimum levels of toxicity (bioluminescence inhibition of Vibrio fischeri bacteria) found in the system were closely related to the maximum and minimum concentrations observed for the reaction intermediaries (hydroquinone and 1,4-benzoquinone). In addition, it was only possible to completely reduce the toxicity of the system after 240 min of reaction when high levels of radiation were applied. [ABSTRACT FROM AUTHOR]

• The effect of inorganic anions in the photo-Fenton degradation of 2,4-D is studied. • A kinetic model is proposed using the ferrioxalate as iron source for pH = 5. • Ferrioxalate improved the photochemical activation of the process. • Kinetic parameters associated with the anions influence were estimated. • A good agreement between the kinetic model and experimental data was observed. The effects of four inorganic anions (Cl−, SO 4 2−, HCO 3 −, NO 3 −) usually present in groundwater were investigated on the photo-Fenton degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). A kinetic model derived from a reaction sequence is proposed using the ferrioxalate complex as iron source at pH close to natural conditions (pH = 5). It was demonstrated that oxalate not only maintained iron in solution for the natural groundwater system, but also increased the photochemical activation of the process. Results showed that the minimum conversion of 2,4-D for the simulated groundwater after 180 min was 63.80%. This value was only 14.1% lower than the conversion achieved without anions. However, with all anions together, the consumption of hydrogen peroxide (HP) per mole of herbicide showed an increase with respect to the test without anions. Only one kinetic parameter was estimated for each anion applying a nonlinear regression method. Subsequently, these optimized kinetic constants were used to simulate the system behaviour, considering the influence of all the studied anions together. A good agreement between kinetic model predictions and experimental data was observed, with the following errors: RMSE 2,4-D = 3.98 × 10−3 mM, RMSE HP = 1.83 × 10−1 mM, RMSE OX = 1.39 × 10−2 mM, and RMSE 2,4-DCP = 5.59 × 10−3 mM. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • TiO 2 -rGO optical properties were estimated using the Monte Carlo method. • TiO 2 -rGO exhibited higher scattering coefficients than TiO 2. • rGO was found to increase quantum efficiency of bare TiO 2. • Complete degradation of clofibric acid was achieved after 6 h of irradiation time. Abstract TiO 2 -reduced graphene oxide (TiO 2 -rGO) photocatalysts with different mass ratios (GO:TiO 2 0.1-0.5-1%) were synthesized via a hydrothermal method and compared through their physico-chemical properties and photocatalytic activity in the degradation of an emerging contaminant, clofibric acid. The optical properties of the TiO 2 -rGO nanocomposites were first estimated in order to calculate the local volumetric rate of photon absorption inside a photocatalytic reactor. Radiation models were solved using the Monte Carlo method. The effect of rGO as well as the photocatalyst loadings on the radiation absorption was evaluated. The lowest photodegradation rate found in P25-rGO 1% was ascribed to an excess of rGO that could well favor charge carriers recombination leading to detrimental photoactivity. A GO/TiO 2 mass ratio of 0.5% provided the fastest initial photodegradation rate under the operating conditions studied here. Finally, the photo-efficiency of all these photocatalysts was also analyzed by calculating the quantum efficiency parameter. The highest value of quantum efficiency was achieved with P25-rGO 0.5% at 100 mg L−1, with an increase of 11% compared to the value obtained for P25-rGO 0%. [ABSTRACT FROM AUTHOR]

The photocatalytic inactivation of Bacillus subtilis spores in air was evaluated employing a fixed-bed reactor with TiO2-coated glass rings, under artificial UV-A radiation. Calculations of the radiation effectively absorbed inside the reactor were carried out by Monte Carlo simulations. The photocatalytic inactivation was assessed by analyzing the viability of the microorganisms retained by the coated glass rings inside the reactor at different irradiation periods. The initial concentration of the spores was reduced by almost 55% at the end of the experiment (12 h). Complementary assays were carried out employing Bacillus subtilis vegetative cells, obtaining a reduction of more than 96% under the same conditions. Two efficiency parameters were computed to assess the reactor performance: the photonic efficiency and the quantum efficiency of inactivation. Results of the efficiency parameters allow an objective comparison of the reactor performance under different experimental conditions and configurations. [ABSTRACT FROM AUTHOR]

The combination of kinetic and spectroscopic tools has become a key scientific methodology for the understanding of catalytic behavior but its application in photocatalysis has inherent difficulties due to the nature of the energy source of the reaction. This review article provides an overview of its use by, first, presenting mechanistically derived kinetic formulations and spectroscopic data handling methods including intrinsic expressions for light and, second, highlighting representative examples of application. To do it we consider universal catalytic systems, particularly (although not exclusively) titania-based materials, and the most frequent hole and/or electron triggered reaction schemes. This review also provides a general framework to pave the way for the future progress of the spectro-kinetic approach in the photocatalysis area. [ABSTRACT FROM AUTHOR]

In this work, MCM-41 materials have been synthesized and modified with different metal loadings of iron by the wet impregnation method. The different meso-structures obtained were characterized by XRD, UVVIS-RD, ICP and TEM and their behaviors as heterogeneous catalysts in the photo-Fenton reaction were studied. Thus, iron-containing mesostructured materials have been successfully tested for the heterogeneous photo-Fenton degradation of atrazine aqueous solutions using UV–vis irradiation at room temperature and close to neutral pH. In order to assess the effectiveness of the herbicide degradation in the heterogeneous photo-Fenton process, and to compare experimental results obtained, a study of the photonic efficiency is presented. The photonic efficiency of Atrazine degradation was evaluated considering different experimental conditions employed two factorial designs. The results showed that the iron modified MCM-41 with a nominal metal loading of 2.5 wt.% exhibited the highest activity. Consequently, the high performance of this material indicates that the heterogeneous via of the photo-Fenton process can also be efficiently employed for the treatment of simulated wastewater containing atrazine, thus presenting advantages unlike the homogeneous process. [ABSTRACT FROM AUTHOR]

A kinetic model derived from a simplified reaction sequence is proposed for the photo-Fenton degradation of Paracetamol (PCT), employing an annular photoreactor. The kinetic model explicitly included the effects of radiation absorption on pollutant degradation kinetics through the evaluation of the Local Volumetric Rate of Photon Absorption (LVRPA). Irradiated experiments achieved an average PCT conversion of 99.3% at 5 min of reaction, and a maximum of 69% of mineralization. Conversely, non-irradiated experiments reached an average PCT conversion of 86.6% at 5 min of reaction, and a maximum of 35% of mineralization. Kinetic parameters ( k 5 = 5.82 × 10 9 , k 6 = 3.01 × 10 10 , k 7 = 6.01 × 10 10 M−1s−1) were estimated employing a nonlinear, multi-parameter regression method, and the validated kinetic model was used to predict temporal variations of the concentrations of HP, PCT, and the main reaction intermediates: hydroquinone (HQ) and 1,4-benzoquinone (BQ). The root mean square error (RMSE) values obtained for HP, PCT, HP, HQ and BQ were 1.16 × 10−2, 7.13 × 10−1, 3.53 × 10−3, 3.05 × 10−3 mM, respectively, showing a good agreement between experimental and predicted data. Moreover, the kinetic model was validated with a new set of experimental tests, confirming its predictive capacity. Beyond the degree of mineralization attained, additional cytotoxicity tests proved that the photo-Fenton process is effective in generating a non-toxic effluent under the operating variables investigated. [Display omitted] • Complete photodegradation of paracetamol was achieved in only 10 min of reaction. • The Volumetric Rate of Photons Absorptions was computed using a 2-D radiation model. • Only three kinetic parameters were estimated in the developed degradation model. • Mean square errors of less than 10% were achieved between model and experimental data. • VERO cells viability of over 95% was obtained for the photodegradation tests. [ABSTRACT FROM AUTHOR]

A commercially available TiO2 type (Kronos vlp 7000), doped with carbon and having an extended spectrum of light absorption wavelength, is investigated for photocatalytic degradation of a representative air pollutant, namely acetaldehyde, under visible light. The modeling of the studied system was carried out including the proposal of kinetic expressions for the contaminant degradation and generation of main intermediates based on the reaction mechanism, the mass balances in the reactor, and the lamps' superficial emission model to evaluate the radiation distribution in the reaction space. The predicted and experimental outlet concentrations of acetaldehyde and formaldehyde as main intermediate were found to be in good agreement obtaining a root mean square error equal to 13 %. [ABSTRACT FROM AUTHOR]

A fixed-bed, annular photoreactor is studied for the photocatalytic disinfection of Escherichia coli aqueous suspensions. Experiments were carried out under UV radiation employing P25 titanium dioxide immobilized onto glass Raschig rings. The photoreactor performance has been simulated following a predicted procedure that takes into account explicitly the radiation absorption step and a series-event disinfection mechanism. The modeling of the radiation field was carried out by Monte Carlo simulation. The reactor model has been compared with experimental data, being able to reproduce the evolution of the concentration of viable bacteria under different bacteria initial concentrations and irradiation levels. [ABSTRACT FROM AUTHOR]

This study reports the application of the photo-Fenton process for the degradation of the herbicide 2,4-dichlorophenoxyacetic (2,4-D). The objective of this research was the evaluation of the procedure at natural pH (pH = 5) using the ferrioxalate complex as iron source at two incident irradiation levels. For this purpose, different combinations of attenuation filters from a solar simulator were tested. Since the process depends on several parameters, the influence of the temperature ( T ) and peroxide to 2,4-D initial concentration ratio ( R ) were investigated and optimized by the application of a three-level factorial experimental design combined with the Response Surface Methodology (RSM). The significance of models and their coefficients were assessed with the analysis of variance (ANOVA). The found optimal conditions were: T = 50 °C and R = 46.3 and T = 41.53 °C and R = 41.46, achieving experimental conversions of 91.4 and 95.9% for the low and high radiation levels, respectively. The obtained results are very close to the values predicted by the quadratic models (93.8 and 100.0%). It was concluded that temperature and hydrogen peroxyde concentration have different influences on the response factor depending on the incident irradiation level. It was demonstrated that RSM is a good tool for studying the effects of different variables and their interactions on 2,4-D conversion percentage in the photo-Fenton process. In addition, solution acute toxicity was also evaluated during the treatments under optimum conditions, since some degradation by-products of 2,4-D can be more toxic than the parent compound. For this purpose, the commonly used Microtox ® test based on the bacteria Vibrio fischeri was employed. [ABSTRACT FROM AUTHOR]

The present work evaluates the enhancement of the photocatalytic inactivation of bacterial spores employing TiO 2 films with silver deposits compared to TiO 2 films without metal deposition. Bacillus subtilis spores spread over TiO 2 films with different silver contents were irradiated with artificial UV-A light. The performances of the coatings were evaluated by the quantum efficiency parameter, which relates the inactivation rate with the radiation absorption rate by the coating. Spectral diffuse transmittance and reflectance measurements of the films were carried out to evaluate the fraction of energy absorbed by the coatings. TiO 2 and Ag/TiO 2 films characterization also included X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Scanning Electron Microscopy (SEM). A notable increase in the photocatalytic inactivation was observed by increasing the silver content of the coatings, reaching a maximum quantum efficiency with the sample containing 1.09 wt.% Ag/TiO 2 . The addition of higher amounts of silver rendered lower inactivation, thus indicating the existence of an optimum Ag/TiO 2 relation. [ABSTRACT FROM AUTHOR]

Optical properties of iron pillaredclays (Fe-PILCs) were determinedby using spectrophotometer measurements coupled with the solutionof the radiative transfer equation (RTE). The specific absorptionand scattering coefficients, as well as the phase function for scattering,were obtained as a function of the wavelength in the range from 300to 500 nm. Optical properties of the Fe-PILCs are greatly affectedby their iron contents which are ascribed to changes in their texturalproperties and are significantly different from those of two otheriron containing materials, goethite and zerovalent iron. To show anapplication of the optical properties, the quantum efficiency of theheterogeneous photo-Fenton process with a Fe-PILC was determined.The results indicate that Fe-PILCs could be used as catalysts in large-scalephotoreactors whose dimensions could be adjusted in a wide range accordingto the catalyst load and iron content to be used. [ABSTRACT FROM AUTHOR]

A kinetic model of the photocatalytic inactivation of Escherichia coli in an annular wall reactor is presented. The model is based on a reaction scheme that involves a series of events in which bacteria are progressively damaged and eventually led to cell lysis. The model explicitly takes into account radiation absorption effects. Photocatalytic inactivation experiments were carried out in a photoreactor operated in a closed recirculating circuit with a reservoir tank and irradiated with a 6 W black light lamp situated in the axis of the reactor. Immobilization of TiO 2 Aeroxide P25 has been carried out by the dip-coating procedure onto the inner-tube wall of the annular reactor. Experimental results for different TiO 2 layer thicknesses were used to estimate the kinetic parameters of the model. Good agreement between model predictions and inactivation experiments was achieved in the whole range of TiO 2 thicknesses studied. [ABSTRACT FROM AUTHOR]

The photocatalytic activity under UV and visible irradiation of a series of CeO2-TiO2 composite materials prepared by microemulsion and subsequently calcined at 500 °C was evaluated using acetaldehyde as a model pollutant. The activities of three composite catalysts containing 2.5, 5 and 25 M% of ceria, as well as a nano-titania reference are compared by means of efficiency parameters; the quantum (or true) efficiency, as well as the photonic (or apparent) efficiency were evaluated. To this end, the lamp emission properties, as well as the radiation field interaction with the catalyst inside the reactor were modeled and numerically calculated. For the evaluation of the radiation absorbed by the catalysts, the optical properties of the materials were measured and a radiative transfer model that considers all potential optical events was built up. The stability of the systems under reaction conditions was also studied. Overall, the results evidence that the composite containing 2.5 Ce mol% outperforms titania by a factor of at least 2, irrespective of the illumination source used in the experiment. This shows the potential of the CeO2-TiO2 composites, a highly active and stable system, for sunlight optimum profiting. [ABSTRACT FROM AUTHOR]

Abstract: A model of a bench-scale, annular, continuous flow reactor for the photocatalytic disinfection of water, operated under conditions of no perfect mixing is presented. The performance of the photoreactor has been simulated following a predictive procedure, with no adjustable parameters, based on the intrinsic kinetics and the information about the geometry, irradiation source and operation conditions (catalysts concentration and its properties as well as the initial concentration of bacteria). The only experimental information required to be determined at laboratory scale are the kinetic parameters of a mechanistic model that takes into account the explicit dependence of the reaction rate with respect to the local volumetric rate of photon absorption (LVRPA) and the optical properties of the catalyst. The proposed model predicts an optimal catalyst concentration in the range 0.1–0.2×10−3 gcm−3, with a significant decrease in the disinfection efficiency for higher catalyst loadings. Important resistances to the mass transport are detected at high TiO2 concentrations, as a result of the low diffusion coefficient of the employed microorganism (Escherichia coli). Operating under the optimal catalyst concentration, model predictions show satisfactory agreement with experimental results extracted from the custom-built bench scale reactor. [Copyright &y& Elsevier]

The performance of different TiO2coatingsis comparedfor the photocatalytic inactivation of dry Bacillus subtilisspores dispersed on TiO2films under UV-A radiation.Three different TiO2coatings were assayed: Degussa P-25,sol–gel, and composite sol–gel/Degussa P-25. The influenceof the increase in the number of TiO2layers was also studied.Furthermore, the amount of TiO2deposited on the borosilicateglass plates and the fraction of energy effectively absorbed by thecatalytic films were determined. Spectral diffuse transmittance andreflectance measurements were performed using a spectroradiometerwith an integrating-sphere attachment. The net-radiation method wasthen applied to evaluate the fraction of energy absorbed by the coatings.To objectively compare the performance of the catalytic films, twotypes of efficiencies were calculated: the photonic efficiency andthe quantum efficiency of inactivation. The highest quantum efficiencywas obtained with the TiO2Degussa P-25 coating with twolayers. [ABSTRACT FROM AUTHOR]

Abstract: A kinetic model of the photocatalytic degradation of the azo dye Acid Orange 7 (AO7) is presented. It is based on mechanistic reaction steps and includes the modeling of the radiation absorption effects. The evaluation of the radiation field inside the reactor was achieved by solving the radiative transfer equation for the heterogeneous system. The study was carried out in a slurry batch photoreactor with recycle, employing artificial UV light as the source of radiation and TiO2 Degussa P25 as catalyst. The biodegradability and toxicity of the irradiated mixture was also assessed. The kinetic model satisfactorily represents the evolution of AO7 under different experimental conditions, with a root mean square error of the estimations of 13.9%. The biodegradability of the AO7 solution was considerably enhanced after the photocatalytic treatment. In addition, a clear reduction of the toxicity of the azo dye was achieved at the end of the experiments. [Copyright &y& Elsevier]

Abstract: This study is focused on the kinetic modelling of the photocatalytic inactivation of bacteria with suspended TiO2. A rigorous model based on a proposed reaction mechanism and accounting explicitly for the rate of photon absorption has been developed. The application of the general kinetic expression to limiting cases suggests that the interaction bacteria–catalyst can be considered to be weak. In contrast, a complex dependence on the radiation absorption rate must be taken into account, as very different radiation conditions may coexist inside the photoreactor, with high absorption rates in the region near to the radiation entrance window and much lower values on the opposite side of the photoreactor. The model has been successfully validated by experimental data, being able to reproduce the evolution of the concentration of viable bacteria in a wide range of values of TiO2 concentration, irradiation power and initial concentration of bacteria with a normalized root mean square logarithmic error of 5.3%. The values of the kinetic parameters are independent of the specific reactor setup or the operating conditions and therefore, the model can be used in a predictive way for photoreactor design and scaling-up, as well as for the optimization of other reactor configurations. [Copyright &y& Elsevier]

This work analyzes the kinetic modelling of the photocatalytic inactivation of E. coli in water using different types of kinetic models; from an empirical equation to an intrinsic kinetic model including explicit radiation absorption effects. Simple empirical equations lead to lower fitting errors, but require a total of 12 parameters to reproduce the results of four inactivation curves when the catalyst concentration was increased. Moreover, these parameters have no physical meaning and cannot be extrapolated to different experimental conditions. The use of a pseudomechanistic model based on a simplified reaction mechanism reduces the number of required kinetic parameters to 6, being the kinetic constant the only parameter that depends on the catalyst concentration. Finally, a simple modification of a kinetic model based on the intrinsic mechanism of photocatalytic reactions including explicit radiation absorption effects achieved the fitting of all the experiments with only three parameters. The main advantage of this approach is that the kinetic parameters estimated for the model become independent of the irradiation form, as well as the reactor size and its geometrical configuration, providing the necessary information for scaling-up and design of commercial-scale photoreactors for water disinfection. [ABSTRACT FROM AUTHOR]

Abstract: A scaling-up methodology for the design of large-scale slurry reactors for the photocatalytic oxidation of cyanide is proposed. The only experimental information required to be determined at laboratory-scale is the intrinsic kinetics that describes the explicit dependence of the reaction rate with the local volumetric rate of photon absorption (LVRPA). Based on the kinetic model and the information about the geometry, irradiation source and the cyanide and catalyst concentrations as operation conditions, the performance of a larger scale reactor has been simulated following a predictive procedure with no adjustable parameters. The validation of the method has been carried out in a bench-scale reactor with ten times higher irradiated volume and a different geometry and irradiation source, in order to ensure that the conclusions about the applicability of the scaling-up model are independent of these parameters. The proposed scaling-up methodology and their correspondent procedures for the evaluation of the LVRPA distribution on the photoreactors has been successfully validated both with commercial TiO2 and a silica-supported TiO2 synthesized in our laboratory. The normalized root mean square error in the verification of the conversions predicted by the model for the larger scale reactor when compared with the experimental data are 7.7% and 6.2% for TiO2 and TiO2/SiO2, respectively. [Copyright &y& Elsevier]

Abstract: This study is focused on the kinetic modeling of the photocatalytic oxidation of cyanide in slurry reactors. The developed model is based on an accepted reaction mechanism and explicitly takes into account the differences in the local volumetric rate of photon absorption (LVRPA) produced by the unavoidable radiation profiles existing in the photoreactor. The model and its correspondent procedures for the evaluation of the LVRPA distribution, and the estimation of the kinetic parameters have been successfully validated with both powder TiO2 and TiO2/SiO2 photocatalysts with improved recovery properties. In both cases, the model reproduces the influence of the catalyst loading, the initial cyanide concentration, and the inlet radiation flux on the reaction rate, with errors below 5%. The kinetic parameters estimated for the model are independent of the irradiation form, as well as the reactor size and its geometrical configuration, providing the necessary information for scaling-up and designing commercial scale photoreactors. [Copyright &y& Elsevier]

Abstract: A kinetic study of the photocatalytic degradation of 4-chlorophenol employing titanium dioxide is presented. Experiments were carried out in a cylindrical slurry reactor irradiated by UV lamps. The aromatic reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of 4-chlorophenol and the main intermediates, 4-chlorocatechol and hydroquinone, were derived from a proposed reaction scheme. These expressions include explicitly the effect of photon absorption on the reaction rate. The modeling of the radiation field in the reactor was accomplished by solving the radiative transfer equation with the discrete ordinate method. Experimental runs were performed by varying the catalyst concentration, the incident radiation, and the reactor length. The parameters of the kinetic model were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with a root mean square error of 14.4%. [Copyright &y& Elsevier]

Abstract: A kinetic expression to represent the photocatalytic degradation of 4-chlorophenol (4-CP) has been derived in a small, well-stirred, slurry reactor. Based on a plausible reaction sequence, the obtained mathematical representation describes with good accuracy the decomposition of 4-CP as well as the evolution of the most important reaction intermediates. This information is used to actionate a very different reactor in size, shape and operating conditions. The adopted approach consists in the precise modeling of the laboratory reactor to estimate intrinsic kinetic parameters. Afterward, the reaction kinetics obtained in the small reactor is used to model a bench scale reactor, without employing any adjustable parameters. Simulation results are in good agreement with the experimental data obtained in the larger reactor. This approach points to the development of a full scale-up procedure employing exclusively laboratory reactor information. [Copyright &y& Elsevier]

Abstract: Despite the large amount of work dealing with supported photocatalysts used to overcome the difficulties associated with the recovery of powdered titania after the photocatalytic treatments, few attempts have been made to calculate the quantum efficiency (η) of these materials. In this work the quantum efficiency for the photooxidation of cyanide with TiO2 and TiO2/SiO2 has been experimentally calculated using an approach based on the resolution of the radiative transfer equation inside the photoreactor. Due to the low absorption coefficient of the silica-supported material, a two-dimensional two-directional reactor model has been developed to describe the photon transport. The dependence of η on the incident radiation flux, the catalysts concentration and the cyanide concentration has been investigated. With both material suspensions, higher quantum efficiencies have been observed when lower radiation fluxes and higher cyanide concentrations are used. However, different trends in the quantum efficiencies are observed when increasing the catalyst concentration, leading to higher values when using powdered TiO2 and lower values for TiO2/SiO2 suspensions. [Copyright &y& Elsevier]

Abstract: The performance of photocatalytic reactors is largely conditioned by their configuration. In particular, photocatalytic wall reactors are affected by configuration-linked factors such as diffusive resistances, reactor radiation incidence and absorption efficiencies, and by the amount of photocatalytic surface area that is effectively irradiated. In this paper, the effect of different configurations and design variables on the performance of annular photocatalytic reactors was analyzed. With this purpose, a complete reactor model was developed and solved, taking into account single- and multi-annular configurations, different reactor dimensions, and three flow patterns. The model was successfully validated against experimental results for the photocatalytic oxidation of perchloroethylene (PCE) in a multi-annular reactor. From the simulation results, it was possible to conclude that the unfavorable effect of the diffusive resistances on the reactor performance could be reduced by constructing photocatalytic annular wall reactors of small annular width and large photocatalytic surface area. Besides, the multi-annular configuration is more effective in using the radiative energy fed into the reactor than the single-annulus reactor configuration. According to the results obtained for PCE photocatalytic degradation, among all the studied reactor configurations the most efficient one is that with its annuli interconnected in a series pattern. [Copyright &y& Elsevier]

Abstract: A multi-annular photocatalytic reactor was designed, that shows good effectiveness for perchloroethylene (PCE) removal from contaminated air streams. In a previous work, a rigorous physical and mathematical model of the photocatalytic reactor was developed and experimentally verified. In this work, this mathematical model was used to study the radiative energy efficiency of the multi-annular photoreactor. The total quantum efficiency is defined as the ratio of the number of molecules of PCE reacted to the number of photons emitted by the lamp, and it is expressed as the product of the following factors: the reactor radiation incidence efficiency, the catalyst radiation absorption efficiency, and the overall reaction quantum efficiency. For the employed reactor, the numerical values of each one were 83%, 92%, and , respectively. Particularly, the dependence of the overall reaction quantum efficiency upon operating variables such as the PCE feed concentration, gas flow rate, irradiation level and relative air humidity was analyzed. These results are useful to optimize the operating conditions and design parameters of the photocatalytic reactor. [Copyright &y& Elsevier]

Abstract: Actinometry is an old and useful method developed in the chemistry field to estimate the amount of photons entering and being absorbed in a reaction cell filled with a well-known reacting system. As it is usually used it is of reduced suitability for intrinsic kinetic studies aimed at scaling-up purposes. However, in photochemical reaction engineering analysis it can be of invaluable help if it is properly applied to accurately calculate the boundary condition that is needed to solve the radiative transfer equation in laboratory photochemical reactors dedicated to obtain intrinsic kinetic parameters. This contribution shows the way that actinometric measurements can be used as one of the most precise and simple methods to estimate the above mentioned boundary condition for both homogeneous and heterogeneous systems, an indispensable parameter to calculate with precise models based in the general radiation transport equation, the light distribution inside the reaction space. This local property is needed to formulate the initiation step of any photochemical reaction scheme when operation is made in the kinetic control regime. Consequently it will be always included in any properly developed complete reaction kinetic model. The proposed extended application is illustrated with one example employing a reactor used in photocatalytic reactions. [Copyright &y& Elsevier]

This work studies in detail the photo-Fenton degradation process of Paracetamol (PCT) on an annular pilot-plant reactor using Computational Fluid Dynamics (CFD). A cylindrical lamp emission model was originally implemented over the structure of the OpenFOAM(R) platform and a multicomponent reaction mixture model was used to compute the temporal evolution of the different species at each point of the reactor. Once the proposed model was experimentally validated, the influence of different operating conditions (i.e. different strategies for hydrogen peroxide (H 2 O 2) dosage, use of low recirculation flow rates (Qr), and a completely uncovered lamp setup) was studied. The results of the analysis showed that a double addition of H 2 O 2 (50% before the tank and 50% before the reactor) significantly reduces the reaction times of the process. Moreover, the overall PCT degradation rate does not change when Qr is increased, thus allowing the system to be operated with a recirculation flow three times lower than that the one used in the experiments. Thereby, the developed model allows identifying the reaction conditions that maximize the overall PCT conversion, making efficient use of H 2 O 2 (main chemical reagent) and reducing the electrical energy consumption (recirculation flow) by operating the system under conditions present in large-scale photochemical reactors. • The photo-Fenton degradation of PCT for different operational conditions was studied. • A complete model of an annular pilot-plant reactor was developed using OpenFOAM(R). • A 3D lamp emission model was used to compute the explicit radiation absorption effects. • The CFD model allows to identify the conditions that maximize the PCT conversion. • An efficient use of oxidant agent and power consumption is obtained for the system. [ABSTRACT FROM AUTHOR]