Optimal Design of a Corrugated-Wall Photocatalytic Reactor Using Efficiencies in Series and Computational Fluid Dynamics (CFD) Modeling

The optimization of a corrugated wall photocatalytic reactor for air 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 was to obtain an optimum for the folding angle, subjected to certain constraints: fixed reactor volume, radiation flux, and gas flow rate. Previous experimentally determined degradation kinetics of a gaseous pollutant was used in the reactor modeling. The simulations of the reactor were performed computationally by using a computational fluid dynamics (CFD) package. The results showed opposed behaviors for the relative catalytic area per unit window area and the relative incident flux with the folding angle. Given that the inner incidence efficiency comprises the product of the two mentioned variables, an optimal folding angle was identified.Fil: Passalia, Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

Integral Design Methodology of Photocatalytic Reactors for Air Pollution Remediation

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.Fil: Passalia, Claudio. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Arsenic removal from water employing a combined system: photooxidation and adsorption

A combined system employing photochemical oxidation (UV/H2O2) and adsorption for arsenic removal from water was designed and evaluated. In this work, a bench-scale photochemical annular reactor was developed being connected alternately to a pair of adsorption columns filled with titanium dioxide (TiO2) and granular ferric hydroxide (GFH). The experiences were performed by varying the relation of As concentration (As (III)/As (V) weight ratio) at constant hydrogen peroxide concentration and incident radiation. Experimental oxidation results were compared with theoretical predictions using an intrinsic kinetic model previously obtained. In addition, the effectiveness of the process was evaluated using a groundwater sample. The mathematical model of the entire system was developed. It could be used as an effective tool for the design and prediction of the behaviour of these types of systems. The combined technology is efficient and promising for arsenic removal to small and medium scale.Fil: Lescano, Maia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); ArgentinaFil: Zalazar, Cristina Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

Supplement to the paper “Packed Bed Photocatalytic Reactors . A Packing Structure Model and its Experimental Validation with Computerized Tomography

The radiation field in photocatalytic packed beds results from direct energy exchange between the lamp and the catalytic beads, and from mutual exchange between beads that are close to each other. The statistical description of these exchange mechanisms requires of the knowledge of the one-particle and two-particle distribution functions. The detailed physical and mathematical basis of a statistical model of the structure of a bed of spherical-like particles of non-negligible diameter, are presented in this supplement. The proposed model has been cast in terms of one and two-particle distribution functions, based on a widely accepted physical picture of the packing structure. The model reproduces the expected bed structure surrounding arbitrarily chosen particles at different distances from the annulus walls. Elsewhere [9], this theoretical model has been validated against results obtained with tomography experiments.Fil: Irazoqui, Horacio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Isla, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Photocatalytic reactors for treating water pollution with solar illumination: A simplified analysis for n-steps flow reactors with recirculation

The concentration of dissolved oxygen in water, in equilibrium with atmospheric air (ca. 8 ppm at 20 C), defines the limits of all practical oxidizing processes for removing pollutants in photocatalytic reactors. To solve this limitation, an alternative approach to that of a continuously aerated reactor is the use of a recirculating system with aeration performed after every cycle at the reactor entering stream. As defined by the nature of a single recirculating step (the need of a reactor operation at a rather low concentration range), this procedure results in a very low photonic efficiency (thus requiring a large photon collecting area and consequently increasing the capital cost). The design engineer will have to resort to a series of several reactors with recirculation. This solution may then lead to a very high Photonic Efficiency for the entire process (i.e., a reduced light harvesting area) at the price of an increase in the required capital cost (due to the larger number of reactors). This paper provides a very simple analysis and analytical expressions that can be used to estimate, for a desired degree of degradation, a trade-off solution between a high number of reactors and a very large surface area to collect the solar photons.Fil: Sagawe, Gerd. Universitaet Hannover Callinstrasse 3; AlemaniaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Bahnemann, Detlef. Universitaet Hannover Callinstrasse 3; AlemaniaFil: Cassano, Alberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Coated mesh photocatalytic reactor for air treatment applications: comparative study of support materials

An experimental comparative study of different meshes as support materials for photocatalytic applications in gas phase is presented. The photocatalytic oxidation of dichloromethane in air was addressed employing different coated meshes in a laboratory-scale, continuous reactor. Two fiberglass meshes and a stainless steel mesh were studied regarding the catalyst load, adherence, and catalytic activity. Titanium dioxide photocatalyst was immobilized on the meshes by dip-coating cycles. Results indicate the feasibility of the dichloromethane elimination in the three cases. When the number of coating cycles was doubled, the achieved conversion levels were increased twofold for stainless steel and threefold for the fiberglass meshes. One of the fiberglass meshes (FG2) showed the highest reactivity per mass of catalyst and per catalytic surface area.Fil: Passalia, Claudio. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Nocetti, Emanuel. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Photocatalytic Reactors. Reaction Kinetics In A Flat Plate Solar Simulator

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: . 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.Fil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rintoul, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cassano, Alberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Arsenic sorption onto titanium dioxide, granular ferric hydroxide and activated alumina: Batch and dynamic studies

The aim of this work was to evaluate and compare the efficiencies of three different adsorbents for arsenic (As) removal from water: titanium dioxide (TiO2), granular ferric hydroxide (GFH) and activated alumina (AA). Equilibrium experiments for dissolved arsenite and arsenate were carried out through batch tests. Freundlich and Langmuir isotherm models were adopted and their parameters were estimated by non-linear regressions. In addition, dynamic experiments were performed in mini fixed bed columns and breakthrough curves were obtained for each combination of sorbate/adsorbent. Experimental results obtained by column assays were compared with predictions of well-known breakthrough models (Bohart?Adams and Clark). Results indicate that As(V) is more easily adsorbed than As(III) for AA and GFH, while TiO2 has a similar behavior for both species. The titanium-based material is the most efficient adsorbent to carry out the process, followed by the GFH.Fil: Lescano, Maia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); ArgentinaFil: Passalia, Claudio. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zalazar, Cristina Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentin

Fotocatálisis Heterogénea Para La Inactivación de Bioaerosoles en Ambientes Interiores

La contaminación del aire representa un importante riesgo medioambiental para la salud y es un problema creciente, especialmente en países en desarrollo. La Organización Mundial de la Salud estimó que una de cada nueve muertes en todo el mundo es el resultado de condiciones relacionadas con la contaminación atmosférica. Últimamente, ha crecido el interés en aspectos que hacen a la contaminación del aire interior, principalmente los que involucran contaminantes de origen microbiológico, conocidos como bioaerosoles debido al riesgo que implican para la salud al encontrarse presentes en la mayoría de los entornos cerrados. Este problema ha impulsado el desarrollo de nuevas tecnologías de purificación, que reemplacen o complementen a los procesos tradicionales de tratamiento. Un proceso atractivo de inactivación de bioaerosoles, es la fotocatálisis heterogénea. Estos procesos se basan en la irradiación con luz UV de suspensiones de óxidos semiconductores como el dióxido de titanio, TiO2, en presencia de las especies contaminantes a degradar. El objetivo principal de este trabajo es el estudio y desarrollo de procesos de inactivación de microorganismos aerotransportados patógenos utilizando filtros de aire absolutos con un fotocatalizador soportado en combinación con radiación UV. Para tal fin se utiliza un fotorreactor de configuración simple de laboratorio. Se aplicaron distintas variantes para determinar el número adecuado de depósitos sobre el soporte filtrante, la duración del ensayo, la dispersión del microorganismo utilizado y el método de recuento de los mismos. Se obtuvieron altas tasas de inactivación (99,9%) en bajos tiempos de contacto (25 minutos). Los resultados demuestran que la fotocatálisis es un proceso viable para la desinfección del aire interior. La utilización de esa técnica permitirá realizar ensayos en los que se puedan determinar los parámetros cinéticos de la desinfección, los que pueden ser utilizados para el desarrollo de dispositivos que posibiliten la descontaminación del aire de espacios interiores.Fil: Flores, Marina Judith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rossenberg, Nadia. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Labas, Marisol Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Kinetic model of water disinfection using peracetic acid including synergistic effects

The disinfection efficiencies of a commercial mixture of peracetic acid against Escherichia coli were studied in laboratory scale experiments. The joint and separate action of two disinfectant agents, hydrogen peroxide and peracetic acid, were evaluated in order to observe synergistic effects. A kinetic model for each component of the mixture and for the commercial mixture was proposed. Through simple mathematical equations, the model describes different stages of attack by disinfectants during the inactivation process. Based on the experiments and the kinetic parameters obtained, it could be established that the efficiency of hydrogen peroxide was much lower than that of peracetic acid alone. However, the contribution of hydrogen peroxide was very important in the commercial mixture. It should be noted that this improvement occurred only after peracetic acid had initiated the attack on the cell. This synergistic effect was successfully explained by the proposed scheme and was verified by experimental results. Besides providing a clearer mechanistic understanding of water disinfection, such models may improve our ability to design reactors.Fil: Flores, Marina Judith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Brandi, Rodolfo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cassano, Alberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Labas, Marisol Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin