Influence of the anodizing process variables on the acidic properties of anodic alumina films

In the present work, the effect of the different variables involved in the process of aluminum anodizing on the total surface acidity of the samples obtained was studied. Aluminum foils were treated by the electro-chemical process of anodic anodizing within the following variable ranges: concentration=1.5-2.5 M; temperature=303-323 K; voltage=10-20 V; time=30-90 min. The total acidity of the samples was characterized by two different methods: acid-base titration using Hammet indicators and potentiometric titration. The results showed that anodizing time, temperature and concentration were the main variables that determined the surface acid properties of the samples, and to a lesser extent voltage. Acidity increased with increasing concentration of the electrolytic bath, whereas the rest of the variables had the opposite effect. Theresults obtained provide a novel tool for variable selection in order to use synthetized materials as catalytic supports, adding to previous research based on the morphology of alumina layers.Fil: Boldrini, Diego Emmanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Tonetto, Gabriela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Morphological changes evaluation by transmission electron microscopy (TEM) of mesoporous catalyst employed in pirolisis of biomass

Durante los procesos de pirólisis de biomasa se producen tres fracciones: una sólida, otra liquida y una gaseosa. En algunos casos, se emplean catalizadores en contacto con la biomasa, para optimizar la degradación de la materia orgánica. A fin de evaluar los posibles cambios morfológicos del catalizador durante el proceso de pirólisis se suele utilizar Microscopía Electrónica de Transmisión (TEM). En este trabajo se presenta un estudio del tamaño de poro y espesor de pared, del catalizador Cu/SBA15 antes y después de la reacción de pirólisis. A partir de los tamaños observados, se determinó que el catalizador no sufre cambios morfológicos durante el proceso de pirólisis, pudiéndose inferir la posible reutilización del mismo en sucesivos procesos. Este aspecto se alinea con los principios de la química verde.In pyrolysis of biomass process: solid, liquid and gas products are obtained. To optimize the organic material degradation, a variety of catalysts are employed. Morphological changes in the catalysts during the pyrolysis reaction are evaluated by Transmission Electron Microscopy (TEM) technique. In this work, a pore and pore wall sizes, before and after pyrolysis process, of a Cu/SBA-15 catalysts are characterized. From results it is observed that the catalyst not present morphological changes in the pyrolysis of biomass, indicating the possible re-use of catalyst in similar succesive processes.Fil: Casoni, Andrés Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca; ArgentinaFil: Volpe, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentin

Morphological and tribological analysis of synthetic and commercial sulfures

Lubrication reduces friction between two surfaces that slide over each other and prevents weldingunder high load conditions. Many lubricant bases enhance their applications by the addition ofadditives. Among them, extreme pressure (EP) additives provide properties that can withstand highload conditions, high temperature and high sliding speeds because they provide a low friction or wearinterface to make contact between the metal parts more efficient [1]. The addition of additives enhanceslubricants applications by providing specific properties suitable for enduring conditions.In this work, the morphology and tribological behavior of bismuth sulfides (Bi2S3) and molybdenumsulfides (MoS2) nanoparticles obtained by solvotermal synthesis and those used in commercialadditives were compared.Fil: Müller, Camila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Avila, Ana Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Bahía Blanca. Unidad de Adm.territorial; ArgentinaFil: Denehy, Mariana. Universidad Nacional del Sur; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Bahía Blanca. Unidad de Adm.territorial; ArgentinaFil: Ciolino, Andrés Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin

Caracterización de tamaños de partícula: comparación entre difracción laser (ld) y microscopía electrónica de barrido (sem)

Two of the most significant properties of particles are size and shape; they often have direct influence on the materials behavior. Since the particulate systems are constituted by 3D particles of different size, the characterization of this property has to be given by a particle size distribution (PSD) . Among the most popular techniques for PSDs measurement, the image analysis (IA) presents some disadvantages: sampling errors, the analysis of only hundred or a few thousand particles to represent the whole population, the use a 2-D projected image of a 3-D particle and long analysis times. In contrast, the laser diffraction technique allows fast particulate systems characterization, processes a high number of particles per assay and provides highly reproducible results. However, LD provides no details about the particle morphology. Both techniques can be considered complementary, however several data interpretation problems appear whe n the results are compared. To do so, it is necessary to understand the meaning of the size descriptors given by each technique and under which conditions the comparison of results from different size analyzers can be done. In this sense, this work explores first the number of particles required to obtain reproducible PSDs by SEM. Then, it presents a comprehensive characterization of PVC particles by assessing a set of size and shape descriptors. The PSDs obtained by IA-SEM and LD were mathematically transformed to be compared. Finally, IA-SEM data was used to evaluate the convenience of using more than one size descriptor to represent the particles volume.Fil: Hegel, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); ArgentinaFil: Jones, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca; ArgentinaFil: Cabrera, Fernanda Anabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca; ArgentinaFil: Bucala, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentin

Effect of the Synthesis Method of MgAl2O4 and of Sn and Pb Addition to Platinum Catalysts on the Behavior in n-Butane Dehydrogenation

The MgAl2O4 spinels, synthesized by using two different methods (ceramic and coprecipitation), show very low acidity and good dispersion capacity of the metallic phase, these properties being suitable for the use of these materials as supports. However, MgAl2O4 cer displays higher strong acidity than MgAl2O4 cop which seems to influence the metal-support interaction, since Pt/MgAl2O4 cer catalyst shows higher metallic dispersion, lower metal particle sizes, and better catalytic behavior than the Pt/MgAl2O4 cop one. The Sn addition to Pt/ MgAl2O4 improves the performance in the n-butane dehydrogenation process, increasing the activity, stability, and selectivity to butenes. This behavior is due to the presence of important Pt-Sn interactions, mainly in bimetallic catalysts supported on MgAl2O4 cer. On the other hand, the Pb addition to monometallic catalysts does not enhance the catalytic performance in dehydrogenation. This behavior is in agreement with the characterization results of metallic phase that indicate important blocking effects in PtPb/MgAl2O4 cer catalysts, and segregation effects in PtPb/MgAl2O4 cop. In conclusion, the ceramic method of MgAl2O4 preparation provides the best support for PtSn catalysts in n-butane dehydrogenation reaction.Fil: Bocanegra, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Scelza, Osvaldo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: de Miguel, Sergio Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Changes in particle area measurements due to SEM accelerating voltage and magnification

Scanning electron microscopy (SEM) images of polymer blends followed by digital image analysis is a rapid and easy method for the measurement of particle size and dispersion. The particle size determination is done with appropriate off-line image analysis software. However, it is necessary to understand how machine parameters involved in the formation of the SEM image influence area measurements of morphological features. In this work, the influence of the accelerating voltage used during image acquisition was examined with standard samples and with polymer blend samples. A systematic study centered on two mutually exclusive assumptions of area variation or no area variation with accelerating voltage was carried out. The off-line image analysis software was then calibrated according to the assumptions. The main conclusion of this study was that kV has an important influence on area measurement in SEM images. This effect was observed for different standard materials (metallic and polymeric) and for the range of magnifications used. The higher the accelerating voltages, the greater the error at high magnification for polymer samples. As the beam energy increases, the primary electrons penetrate more deeply into the solid specimen, producing low-resolution signals. These signals degrade the image and surface details, which became less well defined. Therefore, images of polymer samples must be taken at lower accelerating voltages so the desired surface details can be imaged clearly. To avoid area measurement errors, particle measurement must be done with the calibration of the off-line image analysis software corresponding to the accelerating voltage and magnification used for the acquired images.Fil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Básicas y Aplicadas "Bahía Blanca"(I); ArgentinaFil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentin

Determinación de la Concentración Superficial de Cobre en Catalizadores Soportados a partir de Microscopía (TEM)

Una posible aplicación de los catalizadores de cobre soportados es su empleo en reacciones de hidrogenación selectiva de compuestos a,b-insaturados. En dichas reacciones, el interés se centra en encontrar catalizadores capaces de hidrogenar selectivamente el grupo carbonilo de los compuestos, dejando intacto el enlace olefínico y así obtener alcoholes insaturados. La determinación del tamaño de las partículas de cobre (d) es sumamente importante, dado que la selectividad hacia los alcoholes insaturados depende de dicho parámetro.Fil: Gutierrez, Victoria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Volpe, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Investigation On Pd/SeO2/SiO2 For α-Pinene Oxidation. Characterization by Transmission Electron Microscopy (TEM)

To selectively obtain myrtenal, it is proposed to design a heterogeneous catalyst selective, active, stablewith low selenium load, reusable and efficient to produce the expected aldehyde. In this work, aPd/SeO2/SiO2 catalyst was prepared and tested for the allylic oxidation reactions of α-pinene toselectively obtain a good yield to the desired myrtenal product. To do this, we rely on the selectivity ofSeO2 and the oxidative capacity of Pd. The catalyst is made up of Pd nanoparticles supported on SeO2modified silica [7]. The Pd/SeO2/SiO2 catalyst characterization was carried out mainly by TransmissionElectron Microscopy (TEM) and also by XRD, FTIR, and XPS. TEM study was performed fordetermining Pd particle size both over fresh and used catalyst.Fil: Musso, Florencia Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Volpe, María Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Faraoni, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Bahía Blanca. Unidad de Adm.territorial; Argentin

PMMA-modified divinylester/styrene resins: Phase diagrams and morphologies

Binary and ternary experimental cloud-point curves (CPCs) for systems formulated with a low molar mass synthesized divinylester (DVE) resin, styrene (St), and poly(methyl methacrylate) (PMMA) were determined. The CPCs results were analyzed with the Flory-Huggins (F-H) thermodynamic model taking into account the polydispersity of the DVE and PMMA components, to calculate the different binary interaction parameters and their temperature dependences. The St-DVE system is miscible in all the composition range and down to the crystallization temperature of the St; therefore, the interaction parameter expression reported for a higher molar mass DVE was adapted. The interaction parameters obtained were used to calculate the phase diagrams of the St-PMMA and the DVE-PMMA binary systems and that of the St-DVE-PMMA ternary sys-tern at three different temperatures. Quasiternary phase diagrams show liquid-liquid partial miscibility of the StPMMA and DVE-PMMA pairs. At room temperature, the St-DVE-PMMA system is miscible at all compositions. Final morphologies of PMMA-modified cured St-DVE materials were generated by polymerization-induced phase separation (PIPS) mechanism from initial homogeneous mixtures. SEM and TEM micrographs were obtained to analyze the generated final morphologies, which showed a direct correlation with the initial miscibility of the system.Fil: Schroeder, Walter Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Regional de Investigaciones Básicas y Aplicadas "Bahia Blanca"(i); ArgentinaFil: Aranguren, Mirta Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Borrajo Fernandez, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin