Evaluation of UV and visible light activity of TiO2 catalysts for water remediation

The photocatalytic activity under UV, visible and UV-visible radiation of two commercial catalysts for water remediation are evaluated and compared in a slurry reactor. Bisphenol A (BPA) was employed as the model pollutant. The activities of the carbon-doped, TiO2 catalyst Kronos vlp 7000 and, as a reference, the undoped catalyst Aeroxide P25 are compared by means of efficiency parameters: the overall photonic efficiency and the quantum efficiency. For the evaluation of the radiation absorbed by the catalyst suspensions, the optical properties of TiO2 Kronos vlp 7000 between 300 and 550 nm were measured and reported, as well as the properties of TiO2 Aeroxide P25 in the range 400?550 nm. Kronos catalyst exhibits absorption in the visible range and was almost three times more efficient than Aeroxide for BPA degradation under this condition. However, under UV radiation, Aeroxide P25 quantum efficiency was about 1.5 times the corresponding value of Kronos. Similar BPA photonic and quantum efficiencies were obtained under UV-visible radiation with both commercial catalysts.Fil: Manassero, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET- Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina;Fil: Satuf, María Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET- Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina;Fil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET- Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina

Photocatalytic reactors with suspended and immobilized TiO 2 : Comparative efficiency evaluation

The efficiency of three photocatalytic reactor configurations for the degradation of the micropollutant clofibric acid in water was assessed. The following reaction systems were tested: (i) a slurry reactor with suspended TiO2 particles; (ii) a fixed-film reactor with TiO2 immobilized onto the reactor window; and (iii) a fixed-bed reactor filled with TiO2-coated glass rings. The influence of the catalyst concentration in the suspended system and the number of the catalyst coatings in the immobilized systems were evaluated. The performances of the reactors, under the experimental condition of highest reaction rate for each configuration, were compared with the aid of two parameters: (i) the photonic efficiency (g), which is the ratio of the reaction rate to the rate of incident photons; and (ii) the quantum efficiency (gRxn), which is the ratio of the reaction rate to the photon absorption rate. The obtained values of gRxn were 4.59, 2.96 and 2.02% for the slurry reactor, the fixed-bed reactor and the fixed-film reactor, respectively. Although the slurry reactor was the most efficient configuration, the fixed-bed reactor rendered a value of quantum efficiency only one third lower than the suspended system, making this configuration very convenient for photocatalytic reactions. The analysis of the reaction rate, the photon absorption rate and the quantum efficiency are essential to rationally improve the design, configuration and experimental conditions of photocatalytic reactors.Fil: Manassero, Agustina. 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: Satuf, María Lucila. 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; Argentin

Degradation of Emerging Pollutants by Photocatalysis: Radiation Modeling and Kinetics in Packed-Bed Reactors

Radiation modeling and kinetics in two different packed-bed reactors filled with TiO2-coated glass rings are presented. The first reactor was cylindrical, irradiated from one end by a 150 W mercury lamp. It was employed to obtain the values of the intrinsic kinetic parameters of the degradation of the emerging contaminant clofibric acid (CA). The expression to represent the kinetics of the pollutant was derived from a proposed reaction scheme, and it includes explicitly the effect of photon absorption rate on the reaction rate. The second reactor was annular, irradiated internally and externally by 40 UV-LED lamps. The kinetic parameters calculated in the first reactor were directly employed to simulate the performance of the second one, without using any adjustable parameter. The Monte Carlo method was applied to solve the radiation models in both reactors. Good agreement was obtained between simulation results and experimental data under different operating conditions, with a percentage root-mean-square error of 4.6%. The kinetic parameters proved to be independent of the irradiation source, reactor geometry, and catalyst film thickness, and can be readily applied to design real scale devices

Photon Transport Phenomena: Radiation Absorption and Scattering Effects on Photoreactors

Heterogeneous photocatalysis employing solid semiconductors has been applied to solve a wide variety of environmnetal problems involving the degradation of chemical pollutants and the inactivation of pathogen microorganisms, both in gas and liquid phase. Particularly, heterogeneous photocatalysis is able to tranform refractory organics into readily biodegradable compounds, and eventually mineralized them into carbon dioxide and water.Fil: 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: Manassero, Agustina. 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: Satuf, María Lucila. 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 degradation of an emerging pollutant by TiO2-coated glass rings. A kinetic study

This work presents the photocatalytic degradation of the pharmaceutical drug clofibric acid in a fixed-bed reactor filled with TiO2-coated glass rings. Experiments were carried out under UV radiation. A kinetic model that takes into account radiation absorption by means of the local surface rate of photon absorption (LSRPA) has been developed. The LSRPA was obtained from the results of a radiation model. The Monte Carlo method was employed to solve the radiation model, where the interaction between photons and TiO2-coated rings was considered. Data from experiments carried out with rings with different number of catalyst coatings and different irradiation levels were used to estimate the parameters of the kinetic model. A satisfactory agreement was obtained between model simulations and experimental results.Fil: Manassero, Agustina. 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: Satuf, María Lucila. 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; Argentin

Kinetic modeling of the photocatalytic degradation of clofibric acid in a slurry reactor

A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.Fil: Manassero, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); ArgentinaFil: Satuf, María Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); 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); Argentin

Influence of TIO2-rGO optical properties on the photocatalytic activity and efficiency to photodegrade an emerging pollutant

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodCorrigendum to this paper available at: https://doi.org/10.1016/j.apcatb.2019.03.031 It includes the co-author responsible for the TEM study whose name is L. Pascual and who belongs to the following affiliation: Instituto de Catálisis y Petroleoquímica, ICP-CSIC, C/Marie, Madrid (Spain). It also contains an apology for the mistakeTiO2-reduced graphene oxide (TiO2-rGO) photocatalysts with different mass ratios (GO:TiO2 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 TiO2-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/TiO2 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%.This work has been supported by the Spanish Plan Nacional de I+D+i through the project CTM2015-64895-R and CTM2016-76454-R. Alvaro Tolosana-Moranchel thanks Ministerio de Educación, Cultura y Deporte for his FPU grant (FPU14/01605) and (EST17/00110). The authors are also grateful to Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), and Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) for financial suppor

TiO2-rGO photocatalytic degradation of an emerging pollutant: Kinetic modelling and determination of intrinsic kinetic parameters

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodAn intrinsic kinetic model, derived from a suggested reaction photo-mechanism and with an explicit dependence on the local volumetric rate of photon absorption (LVRPA), was developed to simulate the photocatalytic degradation of clofibric acid and the main reaction intermediates, with a new titania-reduced graphene oxide nanocomposite (TiO2-rGO), The proposed reaction mechanism takes into account that graphene behaves as an electron acceptor and, therefore, this effect was included in the derivation of the reaction rate expressions and in the parameters estimation of the kinetic model. The photodegradation of clofibric acid was performed in a slurry photoreactor under different irradiation levels and using several loadings of a TiO2-rGO nanocomposite, prepared by hydrothermal method with a 0.5»wt. % of GO. Absorbed radiation profiles inside the photoreactor were obtained by solving the radiation model with the Monte Carlo method. A photocatalyst loading of 100»mg»L-1 gave place to the best photodegradation results. Mass balances were proposed for the main pollutant and their main detected intermediates: p-benzoquinone and 4-chlorophenol. The intrinsic kinetic parameters were obtained for the complete (6-parameters) and simplified (5-parameters) models by comparing the experimental and the theoretical concentration values of all the organic compounds detected. The model proved to be able to predict with good accuracy the concentration evolution of clofibric acid, 4-chlorophenol and p-benzoquinone under several photocatalyst concentrations and irradiation levels. Finally, a very good correlation between calculated and experimental values of clofibric acid concentration was obtained with root-mean-square errors below 11%.Thanks are due to the Spanish Plan Nacional I+D+i (projects CTM2015-64895-R and CTM2016-76454-R) and Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), and Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)for financial support. We would also like to thank Antonio C. Negro for his valuable help during the experimental work. Alvaro Tolosana-Moranchel acknowledges to Ministerio de Educación, Cultura y Deporte for his FPU grant (FPU14/01605) and (EST17/00110

Intrinsic kinetics of clofibric acid photocatalytic degradation in a fixed-film reactor

This study presents a kinetic model for the photocatalytic degradation of an organic pollutant in a fixedfilm reactor for water treatment. The pharmaceutical drug clofibric acid (CA) was chosen as the model compound. Experiments were carried out employing TiO2 Aeroxide P25 immobilized on the glass window of a laboratory scale reactor under UV radiation. A kinetic model to represent the degradation of CA was proposed, which explicitly takes into account the absorption of radiation by the catalytic film. Experimental results for different irradiation conditions and different number of TiO2 coatings were used to estimate intrinsic kinetic parameters. External and internal mass transfer limitations were found to be negligible under our operating conditions. Good agreement was obtained between experimental data and model predictions, with a root mean square error of 9.9%.Fil: Manassero, Agustina. 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: Zacarias, Silvia Mercedes. 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: Satuf, María Lucila. 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; Argentin