Nowadays, the use of computational tools in class is quite habitual and important by making the learning process more constructive and dynamic. The objective of this work is to introduce a support didactic material for use in... more
Nowadays, the use of computational tools in class is quite habitual and important by making the learning process more constructive and dynamic. The objective of this work is to introduce a support didactic material for use in computational classes of chemical reaction engineering. The development of the work is based on a direct implementation of proposed examples and problems of the book "Elements of Chemical Reaction Engineering" by Fogler (1999) in the equation-based dynamic simulator: EMSO ™ . The problems were implemented in a way to preserve the structure of the problem as described in the book. The results are shown using graphs generated in the simulator, allowing comparisons with the results presented in the book and detailed analyses for effects of variables in the problem. The problems are easily modified, allowing the student to "experiment" several possibilities, changing equations and values of variables, for example, and observing the results.
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Abstract Carbon dioxide (CO2) photoreduction is a complex process and, despite significant efforts in photocatalyst development, an investigation of the influence of process parameters on photoreduction is still necessary. In this work, a... more
Abstract Carbon dioxide (CO2) photoreduction is a complex process and, despite significant efforts in photocatalyst development, an investigation of the influence of process parameters on photoreduction is still necessary. In this work, a Bi2WO6 photocatalyst was used for the photocatalytic reduction of CO2 in a continuous-flow differential photoreactor and a rotational central composite design (RCCD) was employed for a systematic evaluation and optimization of the operational parameters. The experimental parameters considered were CO2 flow rate, light intensity, partial pressure of H2O, and amount of photocatalyst. The synthesized Bi2WO6 was characterized by XRD, XPS, Raman, SEM, BET measurements and UV–vis spectroscopy. The results showed that the CO2 flow rate had an impact on CO2 photoreduction; the light intensity, partial pressure of H2O, and amount of photocatalyst significantly influenced the CO cumulative production. At optimum conditions (120 mW cm−2, 2.7 kPa, and 15 mg), it was possible to obtain a 60% enhancement in photocatalytic efficiency, compared to the results obtained before the experimental design. Characterization studies carried out after the use of the photocatalyst showed that Bi2WO6 experienced changes on its surface, which may explain the deactivation observed during the photoreduction under gaseous flow.
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Photocatalytic oxidation of glycerol emerges as a potential alternative to contribute to the utilization of surplus glycerol from biodiesel production. In this work, we studied the main reaction parameters for ZnO, i.e. catalyst... more
Photocatalytic oxidation of glycerol emerges as a potential alternative to contribute to the utilization of surplus glycerol from biodiesel production. In this work, we studied the main reaction parameters for ZnO, i.e. catalyst concentration (Ccat), initial pH and temperature (T), evaluating their influence on the conversion, selectivity and yield of the main C3 products (glyceraldehyde - GAD and dihydroxyacetone - DHA). The tests were carried out in a batch reactor (slurry) under UV radiation. The oxidation products were analysed by HPLC. When the parameters were varied individually, glycerol conversion and C3 yield increased with the increase in Ccat, pH and T, but C3 selectivity remained practically unchanged. When the parameters were varied simultaneously in a design of experiments, again the conversion increased as the parameters increased, whereby pH was the most significant variable for conversion and T for the selectivity of both GAD and DHA. The optimum result for conversi...
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Three different lots of a residual Ziegler-Natta catalyst slurry (bearing Ti and Mg) obtained from an industrial petrochemical plant were employed as sources for the photocatalyst supported on silica. The effect of additional magnesium... more
Three different lots of a residual Ziegler-Natta catalyst slurry (bearing Ti and Mg) obtained from an industrial petrochemical plant were employed as sources for the photocatalyst supported on silica. The effect of additional magnesium (1.0-25.0 wt% Mg/SiO2) on the photocatalytic properties of the doped materials was investigated. Doping the titania-based photocatalyst with Mg results in a shift in the absorption threshold toward the visible spectrum. The optical band gap energy of the bare supported photocatalyst was in the range of 2.5 eV and shifted to 1.72 eV after 25 wt% Mg doping. The systems were evaluated for the photodegradation of one dye (rhodamine B (RhB)) and two drugs (paracetamol and diclofenac sodium) either under ultraviolet (UV) (365 nm - UVA) or visible radiation, separately. Among the evaluated systems, doping with 25 wt% Mg afforded the highest degradation values for the target molecules under UV and visible radiation (i.e. 87%, 60% and 55% of the RhB, paracetam...
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Agroindustrial wastes (rice husk, exhausted bark acacia, and tobacco dust) and foundry sands from the iron foundry industry were employed as a support source for photocatalysts. TiCl4 was used as the titanium precursor in the preparation... more
Agroindustrial wastes (rice husk, exhausted bark acacia, and tobacco dust) and foundry sands from the iron foundry industry were employed as a support source for photocatalysts. TiCl4 was used as the titanium precursor in the preparation of the supported photocatalysts. The solids were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), diffuse reflectance spectroscopy over the ultraviolet range (DRS-UV), X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), nitrogen adsorption-desorption at -196 °C and zeta potential (ZP) measurements. The systems were evaluated for the photodegradation of rhodamine B (RhB). Among the tested systems, the highest percentage of dye degradation was reached by the catalyst prepared with foundry sand supports, with values of 65% under ultraviolet and 39% under visible radiation, whereas under the same conditions, the catalyst prepared with rice husk showed the best photocatalytic performance among t...
Research Interests: Materials Science, Catalysis, Metallurgy, Water Purification, Agriculture, and 15 moreSmall Angle X Ray Scattering, Titanium, Scanning Transmission Electron Microscopy, Medicine, Multidisciplinary, Photocatalysis, Light, Nitrogen, Iron, Rhodamine B, Angiosperms, Scanning Electron Microscope, Photodegradation, Industrial Waste, and Photolysis
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The objective of this work is the kinetic study and the reaction rate determination of methane catalytic decomposition over Cu-Ni-Al catalyst for pure hydrogen production. First the rate limiting ste p was investigated. To do so, reaction... more
The objective of this work is the kinetic study and the reaction rate determination of methane catalytic decomposition over Cu-Ni-Al catalyst for pure hydrogen production. First the rate limiting ste p was investigated. To do so, reaction was carried out using four catalyst particle size ranges and the Mears criterion was applied. They showed that the external diffusion effects and diffusion in porous catalysts step do not influence significantly the r eaction rate in the studied conditions. Than the reaction was carried out in a thermobalance with different temperatures (500 to 600°C) and methane concentrations (0.5 to 1.2 mol m -3) in order to determine the reaction rate. It was observed that this is a first order reaction, with activation energy of 50655 J mol -1 . The reaction also forms carbon, which is deposited on the catalyst surface causing deactivation. The carbon oxidation for catalyst regeneration was also investigated. Repeated reaction-regeneration cycles were carried ...
The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were... more
The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were evaluated. Afterward, the suspension catalyst concentration and initial pH to the maximum reaction rate was determined. It was observed that the reaction rate can be approached by a pseudo-first order, with a maximum kinetics constant at 260 mg L-1catalyst concentration and pH 7.7.
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ABSTRACT
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Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet... more
Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet irradiation. The experiments were carried out using commercial (ZnO, TiO2) and non-conventional catalysts, which were prepared from industrial and laboratory waste. Two experimental designs (CCD) were performed for both commercial catalysts, and initial nicotine concentration, catalyst concentration and initial solution pH effects were studied. Then, the synthesized catalysts were tested under the optimal conditions which were found through CCDs. Using commercial catalysts, about 98% of the alkaloid was degraded by ZnO, and 88% by TiO2, in 1h. Among the non-conventional catalysts, the highest photocatalytic degradation (44%) was achieved using the catalyst prepared from a petrochemical industry residue.
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1 Departamento de Engenharia Química, Universidade Federal do Rio Grande do Sul (UFRGS) R. Eng. Luis Englert, s/n. Campus Central. CEP: 90040-040 - Porto Alegre - RS - BRASIL, E-MAIL: {natan, marla, perez}@enq.ufrgs.br ... Resumo: Neste... more
1 Departamento de Engenharia Química, Universidade Federal do Rio Grande do Sul (UFRGS) R. Eng. Luis Englert, s/n. Campus Central. CEP: 90040-040 - Porto Alegre - RS - BRASIL, E-MAIL: {natan, marla, perez}@enq.ufrgs.br ... Resumo: Neste trabalho, foram ...
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Abstract The catalytic decomposition of methane over M–Co–Al (M = Mg, Ni, Zn, Cu) was studied. The samples were prepared by co-precipitation and characterized by SBET, TGA, DTA, TPR and XRD. The carbon produced in the reaction was... more
Abstract The catalytic decomposition of methane over M–Co–Al (M = Mg, Ni, Zn, Cu) was studied. The samples were prepared by co-precipitation and characterized by SBET, TGA, DTA, TPR and XRD. The carbon produced in the reaction was characterized by SEM and TPO. Activity tests were carried out in a thermobalance between 500 and 750 °C. The results show that the textural properties of
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This work is part of a joint project to built a computational tool for power plant simulation, dealing specifically with the reaction chamber (place of the boiler where the fuel is burned). In order to describe the conversion of chemical... more
This work is part of a joint project to built a computational tool for power plant simulation, dealing specifically with the reaction chamber (place of the boiler where the fuel is burned). In order to describe the conversion of chemical energy to thermal energy, an onedimensional pseudo-homogeneous mathematical model, with variable physical properties, and based on mass and energy balances, was developed. The equations were implemented in the gPROMS simulator and the model parameters were estimated using the module gEST of this software, with experimental data from a large-scale coal-fired utility boiler and kinetic data from the open literature. The results showed that the model predicts the composition of the outlet combustion gas satisfactorily.
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The hexavalent chromium, Cr(VI), which is generated in the electroplating process, is toxic to most organisms and potentially harmful to human health. The method generally used for remediation of wastewater containing Cr(VI) employs... more
The hexavalent chromium, Cr(VI), which is generated in the electroplating process, is toxic to most organisms and potentially harmful to human health. The method generally used for remediation of wastewater containing Cr(VI) employs chemicals with high toxicity. This work proposes an alternative technology for the treatment of these wastewaters, based on photochemical reduction of Cr(VI) by alcohols under radiation, which is environmentally sustainable and economically viable. Initially, a batch reactor in laboratory scale was used to determine the best experimental conditions and its specific reaction rate was calculated. Based on these results, a tubular reactor (artificial radiation and sunlight) was designed and built in semi-pilot scale. Tests were carried out with real wastewater from an electroplating industry containing Cr(VI). Tests conducted under sunlight showed a higher total Cr(VI) reduction than the tests with artificial radiation. The remediation of Cr(VI) from wastew...
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Research Interests: Farmacos and fotocatálise
Research Interests: Chemistry, Photocatalysis, Tetracycline, Phenol, Rhodamine B, and 3 moreSlurry, TiO, and fotodegradação
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Hexavalent chromium present in wastewater discharge of galvanic industries is toxic to most microorganisms and potentially harmful to human health. This work examines the photochemical reduction of Cr(VI) with ethanol under ultraviolet... more
Hexavalent chromium present in wastewater discharge of galvanic industries is toxic to most microorganisms and potentially harmful to human health. This work examines the photochemical reduction of Cr(VI) with ethanol under ultraviolet (UV) and visible radiation, and photocatalytic reduction of Cr(VI) with TiO2 in the presence of ethanol under UV radiation. By means of different experimental designs, this study investigates the influence of the initial pH, ethanol amount, catalyst concentration and initial Cr(VI) concentration on total Cr(VI) reduction. The results obtained showed that photochemistry with ethanol under UV radiation (96.10%) was more efficient than photochemistry with ethanol under visible light (48.07%). Furthermore, photocatalysis with TiO2 in the presence of ethanol under UV radiation showed high values of total Cr(VI) reduction: 94.15%, under the optimal conditions established by the experimental design. Finally, experiments were carried out with wastewater disch...
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The application of photochemical reduction of Cr(vi) in the treatment of wastewater from the electroplating industry was studied, and a spiral shaped reactor was designed and constructed (SSR).
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Herein, we have compared the behavior of ZnO and TiO2 in the photocatalytic oxidation of glycerol through detection of the main products. ZnO showed higher selectivity for the products where the ca...
