Estudio numérico y experimental de transporte de momentum y masa en sistemas de adsorcion

ELIAS GARCIA HERNANDEZ (2024)

Esta tesis presenta el análisis experimental y numérico de la adsorción de piridina sobre tela de carbón activado en un adsorbedor de lote de tanque agitado en régimen de flujo de transición y turbulento. Se implemento un modelado numérico tridimensional del proceso de adsorción para la identificación de la velocidad y la concentración locales, además de los gradientes de concentración dentro del adsorbedor. Esto representa un costo computacional elevado en comparación con los modelos convencionales aplicados a la adsorción por lote, como es el caso del modelo cinético de Langmuir. Ambos tipos de modelización producen resultados comparables, sin embargo, la ventaja del modelado 3D es una resolución más detallada de las variables físicas asemejándose más a la realidad, y evitando las suposiciones de mezcla perfecta. Para este efecto, se varió la velocidad de agitación dentro del reactor (30-200 RPM) y la concentración inicial de piridina (99 a 487 mg/L). Como resultado se obtuvieron los parámetros cinéticos y de transporte propios de cada modelo. Además, se identificaron las capas limite hidrodinámicas y de flujo masico alrededor del material adsorbente, las cuales siguen la trayectoria de agitación dentro del reactor. Se observo que el mayor flujo masico de piridina tiene lugar alrededor del adsorbente, principalmente en la zona posterior del impulsor respecto a la dirección de la agitación. esta información es muy relevante en la búsqueda y diseño de sistemas adsorbentes más eficientes y efectivos.

This thesis presents the experimental and numerical analysis of the adsorption of pyridine on activated carbon cloth in a stirred tank batch adsorber in transition and turbulent flow regime. A three-dimensional numerical modeling of the adsorption process was implemented for the identification of the local velocity and concentration, as well as the concentration gradients within the adsorber. This represents a high computational cost compared to conventional models applied to batch adsorption, such as the Langmuir kinetic model. Both types of modeling produce comparable results, however, the advantage of the 3D modeling is a more detailed resolution of the physical variables resembling more closely to reality and avoiding the assumptions of prefect mixing. To this effect, the stirring speed inside the reactor (30-200 RPM) and the initial pyridine concentration (99 to 487 mg/L) were varied. As a result, the kinetic and transport parameters specific to each model were obtained. In addition, the hydrodynamic and mass flow boundary layers around the adsorbent material, which follow the agitation path within the reactor, were identified. It was observed that the highest mass flow of pyridine takes place around the adsorbent, mainly in the area behind the impeller with respect to the direction of agitation.

Tesis de doctorado

CIENCIAS SOCIALES

Strong floristic distinctiveness across Neotropical successional forests

Catarina Jakovac Jorge Arturo Meave del Castillo Frans Bongers Susan Letcher JUAN MANUEL DUPUY RADA Daniel Piotto Danaë Rozendaal Marielos Peña-Claros Dylan Craven Braulio Santos Alexandre Siminski Alfredo Fantini Alice Cristina Rodrigues Alma Hernandez-Jaramillo Álvaro Idárraga-Piedrahita André Junqueira Angelica Almeyda Zambrano Bernardus de Jong Bruno X. Pinho Bryan Finegan Carolina Castellanos Castro Daisy Christiane Zambiazi Daisy Dent Daniel Hernán Garcia-Villalobos Deborah Kennard Diego Delgado Eben Broadbent Edgar Ortiz-Malavasi Eduardo A. Pérez-García Edwin Lebrija-Trejos Erika Berenguer Erika Marin-Spiotta Esteban Alvarez_Davila EVERARDO VALADARES DE SÁ SAMPAIO Felipe Melo Fernando Elias Filipe França Florian Oberleitner Francisco Mora Ardila G. Bruce Williamson Gabriel Colletta George Cabral Geraldine Derroire Geraldo Fernandes Hans van der Wal Heitor Mancini Teixeira Henricus F.M. Vester Hernando Garcia Ima Vieira Jaider Jiménez-Montoya Jarcilene Almeida Cortez Jefferson Hall Jerome Chave Jess Zimmerman Jhon Edison Nieto Vargas Joice Ferreira JORGE ENRIQUE RODRIGUEZ VELAZQUEZ Jorge Ruiz Jos Barlow Jose Aguilar Cano JOSE LUIS HERNANDEZ STEFANONI Julien Engel Justin Becknell Kátia Janaina Zanini Madelon Lohbeck Marcelo Tabarelli Marco Antonio Romero Romero Maria Uriarte Maria das Dores Magalhães Veloso Mário do Espírito Santo Masha van der Sande Michiel van Breugel Miguel Martínez-Ramos Naomi Schwartz Natalia Norden Nathalia Pérez-Cárdenas Noel Antonio González_Valdivia PASCAL PETRONELLI Patricia Balvanera Paulo Massoca Pedro Brancalion Pedro Manuel Villa Peter Hietz Rebecca Ostertag René López Camacho Ricardo Cesar Rita Mesquita Robin Chazdon Rodrigo Muñoz Saara DeWalt Sandra Müller Sandra M Duran Sebastião Martins Susana Ochoa-Gaona Susana Rodriguez-Buritica T. Mitchell Aide Tony Vizcarra Bentos Vanessa de Souza Moreno Laura Vanessa Granda William Thomas Whendee Silver YULE NUNES Lourens Poorter (2022)

Forests that regrow naturally on abandoned fields are important for restoring biodiversity and ecosystem services, but can they also preserve the distinct regional tree floras? Using the floristic composition of 1215 early successional forests (≤20 years) in 75 human-modified landscapes across the Neotropic realm, we identified 14 distinct floristic groups, with a between-group dissimilarity of 0.97. Floristic groups were associated with location, bioregions, soil pH, temperature seasonality, and water availability. Hence, there is large continental-scale variation in the species composition of early successional forests, which is mainly associated with biogeographic and environmental factors but not with human disturbance indicators. This floristic distinctiveness is partially driven by regionally restricted species belonging to widespread genera. Early secondary forests contribute therefore to restoring and conserving the distinctiveness of bioregions across the Neotropical realm, and forest restoration initiatives should use local species to assure that these distinct floras are maintained. Copyright © 2022 The Authors, some rights reserved.

Artículo

CONSERVATION ECOSYSTEMS FORESTRY BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ECOLOGÍA VEGETAL ECOLOGÍA VEGETAL