Simulation of the fractionation of biomass by hydrothermal processes with sub and supercritical water

El trabajo realizado dentro de esta tesis se centra en el desarrollo de modelos cinéticos para la revalorización de biomasa mediante 3 de los procesos más estudiados: fraccionamiento hidrotermal, pirólisis y extracción con fluidos supercríticos. De igual modo, se busca que estos modelos puedan ser utilizados por cualquier persona interesada en ellos. Por lo que, el desarrollo de un entorno amigable para la simulación de dichos procesos es también uno de los objetivos a cumplir. Para el desarrollo de los modelos se procedió al planteamiento de balances de materia no estacionarios (distribuidos o globalizados, según el sistema) a todas las especies involucradas en cada proceso. Dichos balances fueron resueltos mediante una interfaz en Excel, dando lugar a una buena reproducción de los experimentos llevados a cabo en planta piloto y en laboratorio.Departamento de Ingeniería Química y Tecnología del Medio AmbienteDoctorado en Ingeniería Química y Ambienta

Modeling Biosorption Of Cadmium, Zinc And Lead Onto Native And Immobilized Citrus Peels In Batch And Fixed Bed Reactors

Thesis (Ph.D.) University of Alaska Fairbanks, 2012Biosorption, i.e., the passive uptake of pollutants (heavy metals, dyes) from aqueous phase by biosorbents, obtained cheaply from natural sources or industrial/agricultural waste, can be a cost-effective alternative to conventional metal removal methods. Conventional methods such as chemical precipitation, membrane filtration or ion exchange are not suitable to treat large volumes of dilute discharge, such as mining effluent. This study is a continuation of previous research utilizing citrus peels for metal removal in batch reactors. Since fixed bed reactors feature better mass transfer and are typically used in water or waste water treatment using ion-exchange resins, this thesis focuses on packed bed columns. A number of fixed bed experiments were conducted by varying Cd inlet concentration (5-15 mg/L), bed height (24-75 cm) and flow rate (2-15.5 ml/min). Breakthrough and saturation uptake ranged between 14-29 mg/g and 42-45 mg/g respectively. An empty bed contact time of 10 minutes was required for optimum column operation. Breakthrough curves were described by mathematical models, whereby three popular models were shown to be mathematically identical. Citrus peels were immobilized within an alginate matrix to produce uniform granules with higher uptake capacity than raw peels. All breakthrough curves of native and immobilized peels were predicted using external and intra-particle mass transfer resistances from correlations and batch experiments, respectively. Several analogous mathematical models were identified; other frequently used models were shown to be the approximate derivatives of a single parent model. To determine the influence of competing metals, batch and fixed bed experiments were conducted in different binary combinations of Pb, Cd, Zn and Ca. Equilibrium data were analyzed by applying competitive, uncompetitive and partially competitive models. In column applications, high affinity Pb replaced previously bound Zn and Cd in Pb-Zn and Pb-Cd systems, respectively. However, the Cd-Zn system did not show any overshoot. Calcium, which is weakly bound, did not affect target metal binding as much as other metals. Saturated columns were desorbed with 0.1 N nitric acid to recover the metal, achieving concentration factors of 34-129. Finally, 5 g of citrus peels purified 5.40 L mining wastewater

Adsorption and diffusion of gases in Cu-BTC

Ph.DDOCTOR OF PHILOSOPH

Process development for fine chemicals (Acetaldehyde Dimethylacetal) synthesis

Tese de doutoramento. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 200