Ozone as oxidation agent in cyclic activation of biochar

Granular activated carbons were produced from grape seed biochar by cyclic activation with ozone. In each cycle, char was first oxidized by exposure to ozone and then subjected to high temperature in inert atmosphere to desorb oxygen groups formed. The study assessed the influence of operating conditions in the development of porosity, from a starting biochar with narrow microporosity (SBET: 47 m2 g− 1, SDA: 505 m2g− 1) prepared by flash pyrolysis of grape seed at 800 °C. The variables studied were the number of cycles applied and the oxidation and desorption temperatures (250–275 and 850–950 °C, respectively). High oxidation temperatures led to higher burn-off, which was also found to increase with the number of activation cycles. The burn-off needed to achieve a high surface area was lower than in conventional physical activation. After 7–9 activation cycles, activated carbons with SBET higher than 1200 m2 g− 1 and SDA above 1500 m2 g− 1 were obtained. The use of ozone resulted in mainly microporous activated carbons (0.37–0.52 cm3 g− 1) with very low contribution of mesopores (< 0.04–0.07 cm3 g− 1). The mean micropore size increased with the number of activation cycles due to pore widening, while mesopore mean size decreased along the cycles. The activated carbons showed a unique granular morphology with a hollow core and a porous shell, which is maintained even after 10 activation cyclesThe authors greatly appreciatefinancial support from the Spanish Ministerio de Ciencia e Innovación (CTQ2012-32821

Preparation of granular activated carbons from grape seeds by cycles of liquid phase oxidation and thermal desorption

Activation of grape seed char upon successive cycles of liquid phase oxidation followed by high temperature desorption permits a tailored development of porosity. In this work three different oxidants (HNO3, H 2O2, and (NH4)2S2O 8), have been tested and the desorption temperature has been varied within 850-950 C upon 10 activation cycles. A high increase of BET surface area was observed in the first five cycles with HNO3 as oxidizing agent giving rise to values higher than 1200 m2 g- 1 at around 50% burn-off. Activation with H2O2 and (NH 4)2S2O8 led to a significantly lower development of surface area, with 600 and 800 m2 g- 1 respectively at that burn-off. The analysis of the pore size distribution showed that porosity was generated through the creation of new micropores and widening of existing ones upon activation with HNO3 and (NH4) 2S2O8, whereas H2O2 mostly led to the widening of the narrow micropores already existing in the starting char. The activated carbons obtained are essentially microporous, with some small contribution of mesoporosity in the HNO3 series (V micro = 0.69 cm3 g- 1; Vmeso = 0.07 cm3 g- 1). SEM images showed that the activated carbons maintained the granular morphology of the seeds after 10 cycles showing a hollow core structure with a wall thickness of about 200 μmThe authors greatly appreciate the financial support from the Spanish Ministerio de Ciencia e Innovación (CTQ2009-09983

Granular mesoporous activated carbons from waste tires by cyclic oxygen chemisorption-desorption

This document is the accepted manuscript version of a published work that appeared in final form in Industrial and Engineering Chemistry Research, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/ie201499hActivation upon cyclic oxygen chemisorption-desorption has proved to be an efficient way to develop porosity at low burn off from waste tires char. In this work the influence of particle size, desorption temperature, and the number of cycles is studied. Highest values of burnoff and specific surface area (S BET) are obtained for the largest particle diameter (3 mm average) and at intermediate desorption temperature (650 °C). In these conditions S BET values around 500 m 2/g can be achieved at burn-offs of about 30%, and close to 600 m 2/g at around 45% burnoff, with a mean pore size of 10 nm and a micropore volume close to 0.08 cm 3/g. Although the surface area is moderate, the low burnoff and high S BET/burnoff ratio achieved make it possible to maintain initial granular morphology of the particles even after 20 cycles of activationWe greatly appreciate finantial support from the Spanish Ministerio de Educacion y Ciencia through the project CTQ2009-0998

Activation of waste tire char by cyclic liquid-phase oxidation

Activation of waste tire char was performed by successive cycles of liquid-phase oxidation followed by desorption in inert atmosphere at 650 °C. Significant differences in porosity development were found for the three oxidizing agents evaluated: nitric acid > hydrogen peroxide > ammonium persulfate. A linear increase of burn-off with the number of cycles was observed, reaching values between 63 and 90% after 15 activation cycles. Within the range tested, a higher concentration of the oxidizing agent (15 vs 30% v) led to higher burn-off, especially in the case of H2O2, however no differences were observed in terms of BET surface area (S BET) developed per unit of burn-off. SBET values around 750-400 m2/g were obtained by activation with HNO3 and H2O2, respectively. The activated carbons prepared by activation with HNO3 showed much higher mesopore volume (0.47-0.60 cm3/g) and some contribution of microporosity (0.03-15 cm 3/g). The mesopore size distribution in the samples activated with HNO3 (2-7 nm) was displaced to lower values than in the case of H2O2 (4-10 nm). The comparison with cyclic activation with air shows that liquid-phase oxidation provides higher porosity development, especially in the mesopore region but at the expense of higher burn-offThe authors greatly appreciate financial support from the Spanish Ministerio de Ciencia e Innovación (CTQ2009-09983) and the Ministerio de Economía y Competitividad (CTQ2012-32821

Porous structure and morphology of granular chars from flash and conventional pyrolysis of grape seeds

This work studies the influence of the operating conditions used in the pyrolysis of grape seeds on the morphology and textural properties of the chars resulting. Flash and conventional (283Kmin-1 heating rate) pyrolysis have been used within a wide range of temperature (300-1000°C). The effect of a pretreatment for oil extraction has also been studied. The porous structure of the chars was characterized by adsorption of N2 at 77K, Ar at 77K and 87K, and CO2 at 273K and mercury intrusion porosimetry. The morphology was analyzed by scanning electron microscopy. All the materials prepared revealed an essentially microporous structure, with a poor or even negligible contribution of mesopores. Increasing pyrolysis temperature led to higher specific surface areas and lower pore size. The highest specific surface area values occurred within 700-800°C, reaching up to 500m2g-1 with pore sizes in the 0.4-1.1nm range. No significant morphological changes were observed upon carbonization so that the resulting chars were granular materials of similar size than the starting grape seeds. The hollow core structure of the chars, with most of the material allocated at the periphery of the granules can help to overcome the mass transfer limitations of most common (solid or massive) granular activated carbons. The chars showed a good mechanical strength during attrition tests. These chars can be potential candidates for the preparation of granular carbons molecular sieve or activated carbons raw materialsThe authors greatly appreciate financial support from the Spanish Ministerio de Ciencia e Innovación (CTQ2009-09983

Live Demonstration:Neuromorphic Sensory Integration for Combining Sound Source Localization and Collision Avoidance

The brain is able to solve complex tasks in real time by combining different sensory cues with previously acquired knowledge. Inspired by the brain, we designed a neuromorphic demonstrator which combines auditory and visual input to find an obstacle free direction closest to the sound source. The system consists of two event-based sensors (the eDVS for vision and the NAS for audition) mounted onto a pan-tilt unit and a spiking neural network implemented on the SpiNNaker platform. By combining the different sensory information, the demonstrator is able to point at a sound source direction while avoiding obstacles in real time

Proteasome Lid Bridges Mitochondrial Stress with Cdc53/Cullin1 NEDDylation Status

Cycles of Cdc53/Cullin1 rubylation (a.k.a NEDDylation) protect ubiquitin-E3 SCF (Skp1-Cullin1-F-box protein) complexes from self-destruction and play an important role in mediating the ubiquitination of key protein substrates involved in cell cycle progression, development, and survival. Cul1 rubylation is balanced by the COP9 signalosome (CSN), a multi-subunit derubylase that shows 1:1 paralogy to the 26 S proteasome lid. The turnover of SCF substrates and their relevance to various diseases is well studied, yet, the extent by which environmental perturbations influence Cul1 rubylation/derubylation cycles per se is still unclear. In this study, we show that the level of cellular oxidation serves as a molecular switch, determining Cullin1 rubylation/derubylation ratio. We describe a mutant of the proteasome lid subunit, Rpn11 that exhibits accumulated levels of Cullin1-Rub1 conjugates, a characteristic phenotype of csn mutants. By dissecting between distinct phenotypes of rpn11 mutants, proteasome and mitochondria dysfunction, we were able to recognize the high reactive oxygen species (ROS) production during the transition of cells into mitochondrial respiration, as a checkpoint of Cullin1 rubylation in a reversible manner. Thus, the study adds the rubylation cascade to the list of cellular pathways regulated by redox homeostasis

Crecimiento y caracterización de películas delgadas de tio2 y ti1- xfexo2

Titanium dioxide (TiO2) and Fe-doped titanium dioxide (Ti1-xFexO2) thin films were grown on silicon substrates using the magnetron sputtering Rf (13.56 MHz) technique. The relevant growth parameters for the samples (pressure, power, gas mixture ratio, distance between target-substrate, among others) were found. The plasma deposition environment for the ternary films was characterized by optical emission spectroscopy in order to verify and identify the present species which were iron and titanium. The TiO2 films, deposited on silicon substrates [100], showed an amorphous phase while the ternary films showed low crystallinity. After annealing at 800 °C crystalline phases appeared, rutile in binary films and mixed in ternary films.Fil: Galvis, J.. Universidad de Antioquia; ColombiaFil: Ramirez Jimenez, Helena. 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: Montes, J.. Universidad de Antioquia; ColombiaFil: Sanchez, L.. Universidad de Antioquia; ColombiaFil: Beltran, J.. Universidad de Antioquia; ColombiaFil: Barrero, C.. Universidad de Antioquia; ColombiaFil: Morales, A.. Universidad de Antioquia; ColombiaFil: Gomez, J.. Universidad del Quindío; ColombiaFil: Tirado Mejia, L.. Universidad del Quindío; ColombiaFil: Osorio, J.. Universidad de Antioquia; Colombi

Corrosion and tribocorrosion behavior of Ti-Alumina composites

This work focus on the corrosion and wear properties of titanium reinforced with 1% wt. alumina particles, produced by a combination of colloidal techniques and powder metallurgy. The alumina particles were added to control the grain growth of titanium during sintering, and simultaneously to increase hardness and wear resistance. Colloidal techniques permitted a homogeneous dispersion of alumina particles on the surface of fine Ti particles by the formulation of stable aqueous suspensions that were further processed by spray-dry to obtain spherical granules with improved compressibility. Ti-Alumina samples were produced by uniaxial pressing of granules and vacuum sintering leading to materials with homogeneous microstructure, a reduction of grain size higher than 50 % with respect to pure titanium, and a sensible increase in hardness. But the addition of ceramic particles can also have an influence on the corrosion behavior that is one of the most interesting properties of titanium alloys, and on wear resistance, that is one of the drawbacks of Ti. Moreover, the study of simultaneous action of wear and corrosion (tribocorrosion) is an area of highest interest in applications like biomedical or automotive. The corrosion behavior was evaluated by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PP) in NaCl at two concentrations (0.9 % and 3.5 %) and temperatures (37 °C, and room temperature). Tribocorrosion tests were performed using a reciprocating ball-on-plate tribometer where a 10 mm diameter alumina ball was used as counter material, and 10 N normal load was applied during 30 min in the same concentrations and temperatures of NaCl as in the static corrosion test s. The results showed a clear improvement of wear resistance on the composite without reducing the corrosion behavior in both conditions.(undefined)info:eu-repo/semantics/publishedVersio