Facultad Regional Buenos Aires
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Item Preliminary results of photocatalytic Cr(VI) reduction using TiO2 films grown by cathodic arc deposition: effect of the film thickness and the N-doping(2023-06-08) Kleiman, Ariel; Meichtry, Jorge Martín; Xaubet, M.; Grondona, D.; Litter, Marta Irene; Márquez, AdrianaTiO2 is the most studied photocatalyst for the treatment of pollutants; however, its rather large band gap and the need for a removal step when used as a suspension hinder the wide application of this technology. Immobilized TiO2 films grown by cathodic arc deposition (CAD) have shown superior adhesion to the substrate and activities similar to that of P-25 TiO2 films, the reference photocatalyst, but they still require UV light to be excited [1]. N-doping is a strategy frequently used to extend the TiO2 band gap to the visible range [2], but it has a scarce application on CAD-grown films. In this work, TiO2 CAD films, with and without N-doping, were prepared and tested on the photocatalytic removal of Cr(VI), a priority water pollutant, in the presence of ethylenediaminetetraacetic acid (EDTA) as an organic donor. TiO2 films of different thicknesses: (290 ± 40 nm), (440 ± 40) nm, and (850 ± 70) nm, were deposited by CAD according to a reported method [1]. The doping of the films was performed by plasma immersion ion implantation in a N2 environment. For comparison, P-25 TiO2 films of (280 ± 20) nm and (480 ± 30) nm thicknesses were prepared by dip-coating; thicker P-25 films were not stable. All films were grown over a borosilicate glass substrate. Photocatalytic experiments were performed in thermostatted cylindrical glass cells (T = 25 °C) magnetically stirred and irradiated from the top with a HPA 400S lamp (λ > 320 nm, mean UV irradiance 28 W m-2), equipped with an IR filter. 10 mL of a 0.8 mM Cr(VI) and 1 mM EDTA solution at pH 2 (HClO4) were poured into each cell, and 0.25 mL samples were periodically taken for Cr(VI) quantification by the diphenylcarbazide method; at the end of the experiments, a Cr(III)-EDTA complex in solution was determined by direct spectrophotometry [1]. After 5 h of irradiation, Cr(VI) removals of 58% and 85% were obtained with pure and N-doped 290 nm CAD films, respectively, while for pure and N-doped 440 nm CAD films the corresponding removals were 70% and 85%; with the 280 nm and 480 nm P-25 films, Cr(VI) removals were 81% and 88%, respectively. Although thicker CAD films were more efficient (99% of Cr(VI) removal with 850 nm films), no difference could be appreciated between N-doped and undoped films. Cr(VI) evolution could be adjusted to a pseudo-first-order kinetics. In all cases, Cr(III)-EDTA represented 75% of the reduced Cr(VI), the remaining Cr(III) being retained on the TiO2 surface, [1]. The photocatalytic efficiency increased with the thickness of the films. Although P-25 films showed a higher photoactivity than the CAD films of similar thickness, thicker and more active CAD films can be surely obtained in future works. N-doping increased slightly the photocatalytic activity of the thinnest films.Item Photocatalytic NOx removal with TiO2-impregnated 3D-printed PET supports(2023) Binetti Basterrechea, Gian Franco; Montesinos, Victor Nahuel; Quici, NataliaIn this work, the photocatalytic removal of NOx with 3D-printed supports was studied. The technology consisted of a continuous gas flow phase reactor containing a 3D printed PET support impregnated with TiO2 as photocatalyst. The 3D impregnated supports were characterized by diffuse reflectance spectrometry and SEM/EDS. The effect of several key-factors on the removal capacity were studied: type of PET filament (native, BPET vs glycol-modified, PETG), type of TiO2 (P-25 vs Hombikat UV-100), UV-light source (LED vs tubular lamps) and number of deposited TiO2 layers. The highest NO and NOx removal were achieved by only one layer of Hombikat UV-100 over PETG supports, irradiating from both sides of the flat reactor with two sets of black light lamps. This work demonstrate that 3D printing is a reliable and powerful technique for fabrication of photocatalytic reactive supports.Item Photocatalytic CO2 conversion: sol-gel and aerosolization synthesis of CuxO-modified TiO2 over 3D printed supports(2023) Pascual, Julián Ramiro; Altieri, Tamara; Lombardo, María Verónica; Montesinos, Victor Nahuel; Quici, NataliaCuxO-modified TiO2 photocatalysts are powerful materials for conversion of CO2 in methane. However, it is necessary to develop scalable synthesis routes that led to photocatalysts with improved conversion efficiency, elevated photocatalytic activity and low environmental impact. 3D printing facilitates the construction of precise geometrically-controlled reactors in short production times that can speed up the thinking-designing-production cycle of reactors minimizing waste generation. In this work we synthesized CuxO-modified TiO2 photocatalysts following two different routes: (1 ) modification of commercial TiO2 by surface precipitation of Cu2+ (CuxO-TiO2) and (2) one-pot aerosolization of TiO2 and CuxO precursors (CuxO@AerTiO2). The solids were characterized by diffuse reflectance spectroscopy, SEM and XRD. Exploratory experiments for impregnation of photocatalysts in PET monoliths were undertaken. The modification of commercial TiO2 (Aeroxide P25 or Hombikat UV100) was carried out by dropwise addition of 62.9 mL of a 0.05 M Cu2+ solution to 400 mL of a 12.5 g/L of TiO2 suspension in NaOH 0.25 M under continuous stirring. After 4 h, the solid was filtered, washed, dried at 80 °C overnight and, finally, calcinated at 400 °C for 2 h. The effect of copper salt (CuCl2 vs. CuNO3) and Cu loading (0.28, 1 and 5 Cu/Ti At%) was studied. XRD patterns clearly showed the presence of CuO in all cases over the P25 samples, in addition to the anatase and rutile typical signals for the base photocatalyst. When CuCl2 was used as CuxO precursor, well defined nanoparticles of 80 nm where obtained. The synthesis with CuNO3 gave a smooth homogeneous aspect to the solid surface with no distinguishable nanoparticles. The synthesis through aerosolization was based on the one described in the work of Zelcer et al. [1]. Briefly, a solution containing 1.39 g acetylacetone, 1.39 g of glacial acetyc acid, 0.34 g of Ti-iPrOH, 0.0145 g of Cu(NO3)2.3H2O and 0.2 g of Pluronics F127 in 43 mL of MilliQ water was continuously fed to a Büchi B-290 spray drier with a peristaltic pump at a flow rate of 3 mL/min. The liquid was atomized at 220 °C in a two-fluid nozzle with a secondary air-flow of 473 L/h. After collection of the material from the cyclone of the spray drier, the solid was calcined at 440 °C for 4 h. The band-gaps of the synthetized photocatalysts were calculated by the Tauc method being 3.13 eV, 3.17 eV and 3.15 eV for the CuxO-P25, CuxO-UV100 and CuxO@AerTiO2 powders, respectively. Square-based monolith of 3 1.5 3 cm with 15% of PET loading were impregnated by dip-coating in suspensions of 1 – 20 g/L of P25. Once dried at 50°C overnight, all of them were irradiated from one side with a 365 nm UV-LED and the UV-light intensity was measured before and after passing through the impregnated monolith by a 365 nm radiometer. The use of 1 g/L of TiO2 was found as the best option as it absorbs 90% of the UV-light, against the 92.3% absorbed by the monolith impregnated in the 20 g/L suspension. In all cases, the diffuse reflectance spectrum obtained for the Cumodified TiO2 impregnated supports matched the spectrum of the respective powders. The solids synthesized presented promising structural and optical properties and, currently, XRD and SEM analysis are being completed, together with porosimetry for all solids to have broader and comparative information.Item Photocatalytic NOx removal with TiO2-impregnated 3D-printed PET supports(2023-11-20) Binetti Basterrechea, Gian Franco; Montesinos, Victor Nahuel; Quici, NataliaIn this work, we investigated the photocatalytic removal of NOx using 3D-printed supports. Monolithic supports with internal channels were fabricated by Fused Modelling Deposition (FDM) using PET as the filament feedstock. The printing parameters of the supports were optimized to maximize the exposure of the photocatalyst to UV light throughout the monolithic PET printed supports. The removal experiments were carried out in a continuous gas phase flow reactor, which was custom designed in-house incorporating a 3D printed PET support impregnated with TiO2 as photocatalyst. The impregnated and non-impregnated supports were characterized by diffuse reflectance spectrometry, SEM and AFM. The effect of several key-factors on the NOX removal capacity was investigated, including the type of PET filament (native recycled, BPET vs. glycol-modified, PETG), the type of TiO2 (P25 vs Hombikat UV-100), the UV light source (LED vs. tubular lamps), and the number of deposited TiO2 layers. The highest NO and NOx removal were achieved by using PETG supports coated with a single layer of Hombikat UV-100 and irradiating the flat reactor from both sides using two sets of black light lamps. However, the highest selectivity toward nitrate formation was obtained when using P25 under the same experimental conditions. This work demonstrates that 3D printing is a reliable and powerful technique for fabricating photocatalytic reactive supports that can serve as a versatile platform for evaluating photocatalytic performance.Item Propuesta de saneamiento de agua mediante tratamientos fotocatalíticos en Comodoro Rivadavia.(Escuela de Posgrado - Facultad Regional Buenos Aires, 2020-12-14) Leguizamón González, Juliana Andrea; Albarellos, AldoEl presente trabajo se encuentra dividido en dos partes: La primera parte consiste en una investigación de la problemática del agua en Comodoro Rivadavia y las posibilidades de implementar en dicha ciudad la tecnología avanzada de oxidación denominada Fotocatálisis Heterogénea con dióxido de titanio TiO2). La segunda parte es el desarrollo de un plan de negocio de una empresa consultora de tratamientos fotocatalíticos enfocado en el sector farmacéutico: Primera parte: Se hizo una investigación comercial del uso de los tratamientos fotocatalíticos en Comodoro Rivadavia. Se detectaron aplicaciones potenciales en el tratamiento del lago Musters, en la sustitución o combinación de la fotocatálisis heterogénea con TiO2 y el sistema de cloración existente, y en el tratamiento de aguas residuales para ser reutilizadas como agua de riego en proyectos agrícolas. No se encontraron ni proveedores ni proyectos de investigación que sugieran el conocimiento de dicha tecnología. Los usuarios entrevistados manifestaron desconocer qué es y para qué sirve la fotocatálisis heterogénea aplicada a desinfección de aguas. La oferta y demanda de agua de la ciudad superan a la capacidad actual de transformación de contaminantes de la fotocatálisis heterogénea con TiO2; por lo cual se recomienda iniciar proyectos de investigación que validen realmente las posibilidades de uso en los escenarios mencionados. Los clientes potenciales que podrían interesarse por éste tratamiento son la Sociedad Cooperativa de Comodoro Rivadavia (SCPL) y la Municipalidad de Comodoro Rivadavia (MCR); de quienes se intuye preferirían alternativas de tratamientos conocidas y económicas. No obstante, mediante encuestas se determinó que están dispuestos a conocer con mayor detalle dicha tecnología sabiendo que podría ser efectivo en la desinfección de aguas. Se propone que el instrumento mediante el cual podría darse a conocer éstos procesos innovadores sea una empresa consultora especializada en tratamientos fotocatalíticos para apoyar en la inserción de ésta tecnología emergente en procesos reales industriales como estrategia para reducir la brecha entre la investigación y la manufactura en general; con una planificación que contemple un costeo riguroso del proceso de escalamiento industrial y con el desarrollo de un manual de transferencia de tecnología adecuado. Segunda parte: Se desarrolló un plan de negocios para la creación de una empresa consultora de procesos fotocatalíticos. Para comenzar, se transformó la idea de negocio en un modelo de negocio mediante método de canvas “Zen Canvas” de Cho, que es una variación del canvas de Osterwalder y Pigneur. Se determinó que la oportunidad de negocio se encuentra en la realización de investigaciones que hagan un costeo y desarrollen manuales de transferencia de tecnología de los procesos fotocatalíticos para facilitar la transición del laboratorio a la industria. El nicho de mercado elegido fue la eliminación de diclofenac e ibuprofeno en las aguas residuales del sector farmacéutico. La consultora es financiada con recursos propios y recursos de terceros (principalmente subsidios e inversiones “ángeles”). Se encontró que el VPN es de ARS 204.655.567 y un TIR de 221.07%. Palabras clave: Comodoro Rivadavia, Fotocatálisis heterogénea, TiO2, dióxido de titanio, canvas, Zen Canvas, lago Musters, agua potable, aguas residuales, tecnología emergente, escalamiento comercial, manuales de transferencia, costeo de tratamientos fotocataliticos, modelo de negocios, consultoría, procesos avanzados de oxidación.