Diffusion-viscosity decoupling in supercooled glycerol aqueous solutions

The diffusion of ferrocene methanol in supercooled glycerol-water mixtures has been measured over a wide viscosity range, which allowed analyzing the composition dependence of the Stokes-Einstein breakdown (diffusion-viscosity decoupling). The observed decoupling exhibits a common behavior for all studied compositions (glycerol mass fractions between 0.7 and 0.9), determined by the reduced temperature (T/Tg) of the mixtures. This result differs from that reported previously for the diffusion of glycerol in its aqueous solutions, where the reduced temperature for the decoupling decreases with increasing water content. We conclude that the contradictory results are only apparent, and they can be explained by the use of inconsistent extrapolated values of the viscosity of the glycerol-water mixtures in the supercooled region. (Figure Presented).Fil: Trejo González, José Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Longinotti, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Corti, Horacio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Biochar material evaluation through shock electrodialysis phenomenon for sustainable separation devices

The availability of biomass associated with agroindustry residues provides enormous opportunities for new bioproducts applications for sustainable processes. Biochar is a cost-effective carbonaceous material which can serve as raw material to create new separation agents and microdevices for gas purification, water treatment, biomolecule separation, controlled drug delivery, electrochemical reactors, microseparators and many other advanced applications. In this work, we used biochar disks derived from biomass harvest residues as a porous media to study the shock electrodialysis phenomenon. A home-made cell for continuous electrolyte flow including two stainless steel electrodes was used to study this phenomenon. Comparative cyclic voltammetry measurements were performed using the cell in batch mode with 1x10-4 M KCl solution either including or not including the biochar porous media. The difference between both voltammetry profiles showed how the presence of the porous material modified the extension of the plateau zone related to the diffusion-limited current density, which allows to perform shock electrodialysis tests. A set of continuous flow runs considering both distilled water (2.0 ? 6.0 µS/cm) and 1x10-4 M KCl solution (~17 µS/cm) were performed under an applied electric potential previously selected from the voltammetry measurements. The continuous monitoring of the solution ion conductivity in the cell outlet throughout each run provided important insights. The decrease of the outlet ion conductivity when the electric potential was applied to the cell indicated the presence of ion concentration polarization through the biochar porous material. The polarization effect increased when flow velocities and electrolyte concentrations were lower. With a proper engineering design (geometry, thickness and morphology) and considering optimized operating conditions (flow rate, applied voltage and ion concentration), this cost-effective carbonaceous material may play an important role in the development of new separation technologies for water treatment.Fil: Montes, Paula. Universidad Nacional de Tucumán; ArgentinaFil: Antunez, Camila. Universidad Nacional de Tucumán; ArgentinaFil: Trujillo, Matías. Universidad Nacional de Tucumán; ArgentinaFil: Iglesias, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Trejo González, José Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Madrid, Rossana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Avila, Adolfo María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaXXIX Interamerican Congress of Chemical EngineeringTorontoCanadáCanadian Society for Chemical Engineerin

Renewable and Electroactive Biomass-Derived Tubes for CO2Capture in Agroindustrial Processes

Tube-shaped renewable carbon materials were developed to work as separation agents for CO2 capture in agroindustrial and intensive farming facilities. The tubes have electrical properties and moderate CO2 adsorption capacities. These materials can be heated directly through the Joule effect by applying an electric potential between the ends and thus reaching temperatures higher than 473 K in a few seconds with an applied voltage of near 10 V. The tube's temperature can be easily controlled by manipulating the applied voltage, which is of interest for the development and design of CO2 capture processes through electric swing adsorption. The tubular form of the material also provides the alternative to be filled up with adsorbents like zeolite and metal-organic frameworks to produce highly selective structured adsorbents based on renewable carbon materials with the advantage of providing direct Joule heating. These materials were studied as separation agents to be part of cycles like vacuum swing adsorption, electric swing adsorption, and both combined. The tubes were tested through consecutive and repeated adsorption and Joule heating desorption experiments. The dynamics of the tube's temperature and the CO2 gas-phase composition showed consistency and repeatability. The results revealed the robustness and reliability of the biomass-derived tubes to work as separation agents for CO2 capture.Fil: Aráoz, María Emilse. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Marcial, Adrián Facundo. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Trejo González, José Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Avila, Adolfo María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin

The viscosity of glycerol-water mixtures including the supercooled region

The dynamic viscosity of water, glycerol, and its mixtures over a wide range of temperatures, including the supercooled region, was calculated resorting to several predictive approaches and compared to published data. The temperature dependence of the viscosity of the pure components can be described within the experimental error using different empirical equations. However, the best fit is obtained by the Avramov-Milchev equation, taking into account that this equation has only two adjustable parameters. The same model was also used to describe the viscosity of the mixtures over the entire range of temperatures and compositions where experimental data are available and to extrapolate the viscosities of the mixtures at temperatures close to the glass transition. We calculated the viscosities of glycerol-water mixtures, over the entire range of compositions, between (238.15 and 273.15) K. The agreement with experimental data in the stable liquid region is very good, which makes our predictions in the supercooled region fairly reliable. The analysis of the glycerol-water mixtures reveals that, in contrast to that previously found in other aqueous polyol solutions such as sucrose and trehalose, the temperature and composition dependence of the viscosity cannot be described with a scaled Arrhenius equation. At low temperatures, the excess viscosity of the glycerol-water mixtures can be very well described by a regular-like solution coefficient. © 2011 American Chemical Society.Fil: Trejo González, José Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Longinotti, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Corti, Horacio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Comisión Nacional de Energía Atómica; Argentin

Renewable carbon-based materials for enhanced ion concentration polarization in sustainable separation devices

Renewable carbon-based materials derived from sugarcane harvest residues were used as a porous medium to study the enhancement effect of ion concentration polarization as an emerging electrolyte separation concept. A home-made cell for continuous electrolyte flow including two electrodes was used to study this process. A set of continuous flow runs using 0.1 mM KCl solution were performed under applied electric potentials between 0.0-5.0 V. A decrease of the outlet ion conductivity was obtained when the electric potential was applied to the cell. The depletion effect increased when flow velocities were lower and the phenomenon was reversible as the voltage was turned off. A 25 % conductivity drop was achieved for an electrolyte flow rate of 0.7 ccm. The conductivity drop was higher for less permeable porous medium, i.e., tighter biochar porous material. This is an example of how renewable biomass-derived materials can be integrated into the manufacturing of new separation devices.Fil: Montes, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Trejo González, José Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Aráoz, María Emilse. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Iglesias, Gabriela Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Trujillo, Ricardo Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Madrid, Rossana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Avila, Adolfo María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin

Regímenes de bienestar y políticas sectoriales en América Latina

Este libro presenta un resumen de los 15 trabajos emanados del Workshop, en el cual participaron 29 académicos de instituciones de México, España, Argentina y Venezuela. Los autores reflexionan sobre los problemas que ha enfrentado el débil Estado de bienestar en la región, los alcances y limitaciones de la política social de combate a la pobreza, así como las debilidades de los sistemas educativo y de salud en lo que respecta a la resolución de los conflictos sociales que están obligados a atender.Secretaría de Educación Pública - Subsecretaría de Educación Superior - Dirección de Educación Superior Universitaria. Convenio con la SEP: 2017-15-001-017