Adsorption processes for CO2 capture from biogas streams

Tesis doctorial presentada en el Departamento de Energía de la Universidad de Oviedo, Junio 2016[EN] In the current energy scenario, commitment to the reduction of fossil fuel dependency has increased interest in alternative energy sources, one example of which is biogas, whose commercial value has grown remarkably in recent years. The present study deals with the topic of CO2 capture by means of adsorption on solid sorbents. More precisely, it focuses on the separation of CO2 from representative biogas streams (CO2/CH4 mixtures) at different pressures and feed concentrations. Adsorption using solid sorbents is a promising alternative technology to the more widely deployed physical absorption. In this PhD dissertation the use of sustainable low-cost adsorbents produced from cherry stones by means of single-step activation with carbon dioxide and steam is explored. Activation conditions were optimized by applying Response Surface Methodology to study the combined effect of temperature, solid yield and heating rate during activation on CO2 uptake at 25 ˚C and at atmospheric pressure. An experimental design was pursued and the activation conditions that maximize CO2 capture capacity of each activating agent were identified. Activated carbons were then produced on a larger scale for the adsorption tests. Carbons were characterized in terms of texture and chemical composition and CO2 adsorption capacities were evaluated under static conditions, by means of thermogravimetry, and dynamic conditions, in a purpose-built fixed-bed. Single component adsorption isotherms of CO2 and CH4 were measured at different temperatures (30, 50 and 70 ˚C) and up to pressures of 10 bar to screen adsorbents in terms of equilibrium selectivity for the separation of CO2 from CO2/CH4 mixtures. The results indicate that the biomass-based carbons are highly selective, high-capacity CO2 adsorbents. Single component adsorption isotherms were fitted to the Toth and Sips models and the parameters were used to estimate the adsorption equilibrium from binary CO2/CH4 mixtures. From these data an Adsorption Performance Indicator (API) was estimated and the values confirmed the potential of the biomass-based activated carbons for biogas upgrading. The performance of the adsorbents under dynamic conditions was evaluated in a lab-scale fixedbed setup by means of consecutive adsorption-desorption cycles to assess the breakthrough curves of CO2 and CH4. For this purpose, a binary equimolar mixture of CO2 and CH4 was fed into the bed at different pressures (1, 3, 5 and 10 bar) and under isothermal (30 ˚C) conditions. The biomass-based carbons showed a superior performance to a commercial activated carbon, Calgon BPL, which was used as a reference in the present study. The kinetic performance of the adsorbents was also explored by means of transient breakthrough experiments at atmospheric pressure and at 30 ˚C and by feeding CO2/CH4 mixtures of variable compositions into the bed. The experimental data obtained were fitted to kinetic models (pseudo-first order, pseudo-second order and Avrami) and the mechanism involved in the mass transfer during adsorption was analysed by means of diffusion-based models (intra-particle and Boyd). The results indicate that there was more than one mass mass transfer mechanism involved in the adsorption of CO2 from CO2/CH4 on these biomass-based carbons. Moreover, the cherry stone-based carbons showed faster kinetics than the commercial carbon Calgon BPL.[ES] En el escenario energético actual, el compromiso hacia la reducción de la dependencia de los combustibles fósiles ha hecho crecer el interés por la investigación en fuentes de energía alternativas; tal es el caso del biogás, cuyo valor comercial ha aumentado en los últimos años. El presente trabajo se enmarca dentro de la temática de captura de CO2 mediante adsorción con sólidos. En concreto, en la separación de CO2 de corrientes de biogás (CO2/CH4) a diferentes presiones y concentraciones. La adsorción con sólidos se plantea como una tecnología prometedora frente a otros procesos como la absorción física. En esta Tesis Doctoral se propone el uso de adsorbentes sostenibles y de bajo coste, preparados a partir de huesos de cereza mediante activación física en una sola etapa con dos agentes activantes: dióxido de carbono y vapor de agua. La optimización de las condiciones de activación se ha llevado a cabo mediante la aplicación de la Metodología de Superficies de Respuesta, estudiando el efecto combinado de la temperatura, el rendimiento de sólido y la velocidad de calentamiento del proceso de activación sobre la capacidad de captura de CO2 a 25 ˚C y presión atmosférica. Para ello, se ha aplicado un diseño estadístico de experimentos y se han identificado aquellas condiciones que maximizan la capacidad de captura de CO2 para cada uno de los agentes activantes. Una vez identificadas dichas condiciones, los carbones activados se prepararon en cantidad suficiente para realizar estudios de adsorción a mayor escala. Seguidamente, se caracterizaron los adsorbentes química y texturalmente, y se evaluó su capacidad de adsorción de CO2 en condiciones estáticas, por termogravimetría, y dinámicas, en lecho fijo. Se determinaron las isotermas de adsorción de CO2 y CH4 a diferentes temperaturas (30, 50 y 70 ˚C) y hasta 10 bar de presión, con objeto de evaluar la selectividad de los adsorbentes para la separación de CO2 de mezclas CO2/CH4. Los resultados obtenidos indicaron unas selectividades y capacidades de adsorción de CO2 elevadas. Las isotermas se ajustaron a los modelos de Sips y Toth cuyos parámetros de ajuste permitieron estimar el equilibrio de adsorción de una mezcla binaria CO2/CH4. A partir de estos resultados se determinó un indicador de rendimiento (API, acrónimo del inglés Adsorption Performance Indicator) el cual corroboró el potencial de los carbones activados biomásicos para la purificación de biogás. El comportamiento de los adsorbentes en condiciones dinámicas se evaluó en un lecho fijo, mediante ciclos múltiples de adsorción y desorción, obteniendo las curvas de ruptura de CO2 y CH4. Para ello, se trabajó con una mezcla binaria equimolar de CO2 y CH4 a distintas presiones (1, 3, 5 y 10 bar) y a 30 ˚C, como alimentación al lecho. El comportamiento mostrado por los carbones activados preparados a partir de huesos de cereza fue superior al del carbón activado comercial Calgon BPL, utilizado como referencia en este trabajo. Asimismo, se evaluó el comportamiento cinético de los adsorbentes para lo cual se realizaron experimentos dinámicos a presión atmosférica y a 30 ºC alimentando mezclas binarias CO2/CH4 de distinta composición. Los datos experimentales se ajustaron a modelos cinéticos (pseudoprimer orden, pseudo-segundo orden, y Avrami) y se estudió el mecanismo de transferencia de materia durante el proceso de adsorción mediante modelos difusionales (intra-particular y Boyd). Los resultados obtenidos indican que no existe una única etapa controlante en el proceso de adsorción de CO2 de mezclas CO2/CH4 en los adsorbentes biomásicos preparados. Por otro lado, la cinética de adsorción es significativamente más rápida en los carbones activados biomásicos que en el carbón comercial, Calgon BPL.Peer reviewe

Dynamic performance of biomass based carbons for CO2/CH4 separation. Approximation to a PSA process for biogas upgrading

Physical adsorption-based processes such as pressure swing adsorption (PSA) constitute an alternative to selectively adsorb CO2 from biogas streams. There is abundant work regarding the equilibrium of adsorption of pure CH4 and CO2 on different adsorbents. However, to design an adsorption process with a selected adsorbent it is very important to account for its dynamic behavior in a packed-bed. Thus, the performance of two biomass-based activated carbons (CS-CO2 and CS-H2O) previously prepared in our laboratory to separate CO2/CH4 has been evaluated. Full adsorption–desorption cycles were conducted at 30 °C (isothermal conditions) and different pressures (1, 3, 5, and 10 bar) feeding binary CO2/CH4 (50/50 vol %) mixtures to a purpose-built fixed-bed setup. A commercial activated carbon, Calgon BPL, was also evaluated for reference purposes. CO2 equilibrium uptakes were obtained from dynamic breakthrough curves and proved to be maximum at 10 bar (5.14, 4.48, and 4.14 mol kg–1 for CS-CO2, CS-H2O, and Calgon BPL, respectively). However, the CO2/CH4 separation efficiency, according to the difference in breakthrough times between CH4 and CO2, is very limited at 10 bar. A combined analysis of the productivity and purity of CH4 along with CO2 working capacity derived from dynamic experiments indicates that our biomass-based activated carbons would be better candidate materials for the CO2/CH4 separation at a pressure of 5 bar than the commercial activated carbon Calgon BPL.This work has received financial support from the Spanish MINECO (Project ENE2011-23467), 437 co-financed by the European Regional Development Fund (ERDF), and from the Gobierno del 438 Principado de Asturias (PCTI2013-2017, GRUPIN14-079).Peer reviewe

Kinetics of CO2 adsorption on cherry stone-based carbons in CO2/CH4 separations

Most practical applications of solids in industry involve porous materials and adsorption processes. A correct assessment of the equilibrium and kinetics of adsorption is extremely important for the design and operation of adsorption based processes. In our previous studies we focused on the evaluation of the equilibrium of CO2/CH4 adsorption on cherry stone-based carbons. In the present paper the kinetics of adsorption of CO2 on two cherry stone-based activated carbons (CS-H2O and CS-CO2), previously prepared in our laboratory, has been evaluated by means of transient breakthrough experiments at different CO2/CH4 feed concentrations, at atmospheric pressure and 30 °C. A commercial activated carbon, Calgon BPL, has also been evaluated for reference purposes. Three models have been applied to estimate the rate parameters during the adsorption of CO2 on these carbons, pseudo-first, pseudo-second and Avrami´s fractional order kinetic models. Avrami´s model accurately predicted the dynamic CO2 adsorption performance of the carbons for the different feed gas compositions. To further investigate the mechanism of CO2 adsorption on CS-H2O, CSCO2 and Calgon BPL, intra-particle diffusion and Boyd´s film-diffusion models were also evaluated. It was established that mass transfer during the adsorption of CO2 from CO2/CH4 is a diffusion-based process and that the main diffusion mechanisms involved are intra-particle and film diffusion. At the initial stages of adsorption, film diffusion resistance governed the adsorption rate, whereas intra-particle diffusion resistance was the predominant factor in the following stages of adsorption.This work has received financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF), and from the Gobierno del Principado de Asturias (PCTI 2013-2017 GRUPIN14-079). N.A-G. also acknowledges a fellowship awarded by the Spanish MINECO (FPI program), and co-financed by the European Social Fund.Peer reviewe

Signaling through the leukocyte integrin LFA-1 in T cells induces a transient activation of Rac-1 that is regulated by Vav and PI3K/Akt-1

12 p.-8 fig.Integrin LFA-1 is a receptor that is able to transmit multiple intracellular signals in leukocytes. Herein we show that LFA-1 induces a potent and transient increase in the activity of the small GTPase Rac-1 in T cells. Maximal Rac-1 activity peaked 10-15 min after LFA-1 stimulation and rapidly declined to basal levels at longer times. We have identified Vav, a guanine nucleotide exchange factor for Rac-1, and PI3K/Akt, as regulators of the activation and inactivation phases of the activity of Rac-1, respectively, in the context of LFA-1 signaling based on the following experimental evidence: (i) LFA-1 induced activation of Vav and PI3K/Akt with kinetics consistent with a regulatory role for these molecules on Rac-1, (ii) overexpression of a constitutively active Vav mutant induces activation of Rac independently of LFA-1 stimulation whereas overexpression of a dominant-negative Vav mutant blocks LFA-1-mediated Rac activation, (iii) pharmacological inhibition of PI3K/Akt prevented the fall in the activity of Rac-1 after its initial activation but had no effect on Vav activity, and (iv) overexpression of a dominant-negative or a constitutively active Akt-1 induced or inhibited, respectively, Rac-1 activity. Finally, we show that T cells with a sustained Rac activity have impaired capacity to elongate onto ICAM-1. These results demonstrate that down-regulation of the activity of this GTPase is a requirement for the regulation of T cell morphology and motility and highlight the importance of temporal regulation of the signaling triggered from this integrin.This work was supported in part by Grants CICYT SAF 2001–2807 from Ministerio de Ciencia y Tecnología and FIS-01/1367 from Ministerio de Sanidad y Consumo (to C. C.), a fellowship from Comunidad de Madrid (to L. S.-M.), a Formación de Profesorado Universitario predoctoral fellowship from Ministerio de Educación, Cultura y Deporte (to N. S.-S.), and a postdoctoral fellowship from Ministerio de Educación, Cultura y Deporte (to M. D. G.-L.).Peer reviewe

A Telehealth-Based Cognitive-Adaptive Training (e-OTCAT) to Prevent Cancer and Chemotherapy-Related Cognitive Impairment in Women with Breast Cancer: Protocol for a Randomized Controlled Trial

Background: Many women with breast cancer experience a great number of side effects, such as cognitive impairment, during and after chemotherapy that reduces their quality of life. Currently, research focusing on the use of non-pharmacological, and specifically telehealth interventions to prevent or mitigate them has been insufficient. Methods: This protocol describes a randomized controlled trial aimed at studying the preventive effects of a videoconferenced cognitive-adaptive training (e-OTCAT) program (ClinicalTrials.gov NCT04783402). A number of 98 eligible participants will be randomized to one of the following groups: (a) the experimental group receiving the e-OTCAT program during 12 consecutive weeks since the beginning of chemotherapy; and (b) the control group receiving and educational handbook and usual care. The primary outcome will be the cognitive function. Secondary measures will be psychological distress, fatigue, sleep disturbance, quality of life and occupational performance. The time-points for these measures will be placed at baseline, after 12 weeks and six months of post-randomization. Conclusion: This trial may support the inclusion of multidimensional interventions through a telehealth approach in a worldwide growing population suffering from breast cancer, emphasizing the prevention of cognitive impairment as one of the side effects of cancer and its treatments.Spanish Government FPU17/00939 FPU18/03575Instituto de Salud Carlos III FI19/0023

Effectiveness of an intervention for improving drug prescription in primary care patients with multimorbidity and polypharmacy:Study protocol of a cluster randomized clinical trial (Multi-PAP project)

This study was funded by the Fondo de Investigaciones Sanitarias ISCIII (Grant Numbers PI15/00276, PI15/00572, PI15/00996), REDISSEC (Project Numbers RD12/0001/0012, RD16/0001/0005), and the European Regional Development Fund ("A way to build Europe").Background: Multimorbidity is associated with negative effects both on people's health and on healthcare systems. A key problem linked to multimorbidity is polypharmacy, which in turn is associated with increased risk of partly preventable adverse effects, including mortality. The Ariadne principles describe a model of care based on a thorough assessment of diseases, treatments (and potential interactions), clinical status, context and preferences of patients with multimorbidity, with the aim of prioritizing and sharing realistic treatment goals that guide an individualized management. The aim of this study is to evaluate the effectiveness of a complex intervention that implements the Ariadne principles in a population of young-old patients with multimorbidity and polypharmacy. The intervention seeks to improve the appropriateness of prescribing in primary care (PC), as measured by the medication appropriateness index (MAI) score at 6 and 12months, as compared with usual care. Methods/Design: Design:pragmatic cluster randomized clinical trial. Unit of randomization: family physician (FP). Unit of analysis: patient. Scope: PC health centres in three autonomous communities: Aragon, Madrid, and Andalusia (Spain). Population: patients aged 65-74years with multimorbidity (≥3 chronic diseases) and polypharmacy (≥5 drugs prescribed in ≥3months). Sample size: n=400 (200 per study arm). Intervention: complex intervention based on the implementation of the Ariadne principles with two components: (1) FP training and (2) FP-patient interview. Outcomes: MAI score, health services use, quality of life (Euroqol 5D-5L), pharmacotherapy and adherence to treatment (Morisky-Green, Haynes-Sackett), and clinical and socio-demographic variables. Statistical analysis: primary outcome is the difference in MAI score between T0 and T1 and corresponding 95% confidence interval. Adjustment for confounding factors will be performed by multilevel analysis. All analyses will be carried out in accordance with the intention-to-treat principle. Discussion: It is essential to provide evidence concerning interventions on PC patients with polypharmacy and multimorbidity, conducted in the context of routine clinical practice, and involving young-old patients with significant potential for preventing negative health outcomes. Trial registration: Clinicaltrials.gov, NCT02866799Publisher PDFPeer reviewe

Geodivulgar: Geología y Sociedad 2018

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasFALSEsubmitte

GEODIVULGAR: Geología y Sociedad

Fac. de Ciencias GeológicasFALSEsubmitte

Precariedad, exclusión social y diversidad funcional (discapacidad): lógicas y efectos subjetivos del sufrimiento social contemporáneo (III). Innovación docente en Filosofía

El PIMCD Precariedad, exclusión social y diversidad funcional (discapacidad): lógicas y efectos subjetivos del sufrimiento social contemporáneo (III). Innovación docente en Filosofía se ocupa de conceptos que generalmente han tendido a ser eludidos en la enseñanza académica de filosofía. Se trata de la tercera edición de un PIMCD que ha venido recibiendo financiación en las últimas convocatorias PIMCD UCM, de los que se han derivado publicaciones colectivas publicadas por Ediciones Complutense y Siglo XXI