O presente trabalho teve como objetivo verificar a potencialidade do óleo de macaúba como matéria-prima para síntese de biodiesel pela rota enzimática. Utilizou-se como proposta a transesterificação do óleo de macaúba com etanol mediada pela enzima lipase em fluxo contínuo empregando reator de leito fixo, visando obter amostras de biodiesel com propriedades adequadas à sua utilização como biocombustível. A enzima selecionada para desenvolvimento experimental foi a lipase microbiana de Burkholderia cepacia imobilizada em suporte híbrido não comercial (SiO2-PVA). Foram testados reatores de leito fixo de um estágio e dois estágios. A primeira etapa do trabalho foi direcionada para testes visando avaliar a influência da razão entre a altura (l) e o diâmetro (d) do reator de leito fixo na etanólise do óleo de macaúba. As reações foram operadas continuamente por 20 dias, utilizando óleo: etanol numa razão molar de 1:12 na ausência de solvente e tempo espacial de 14h. Dois reatores foram testados: Reator A (l = 55 mm e d = 15 mm) e Reator B (l = 210 mm e d = 14 mm), apresentando relação geométrica (l/d) de 3,7 e 15, respectivamente. Os dados obtidos indicaram influência das dimensões da coluna empacotada na produção de biodiesel e nas condições testadas, a maior razão altura/ diâmetro não interferiu na transferência de massa do fluido através da coluna. O melhor desempenho foi obtido no sistema experimental que empregou o reator B, atingindo 89,7 ± 4,8% de rendimento e 40,4 ± 2,2 mgéster.gmeio -1.h--1 de produtividade. Na sequência o trabalho foi direcionado para a execução de testes empregando reatores de leito fixo (Reator B) duplo estágio incorporando uma coluna empacotada com resina catiônica (Lewatit® GF 202) para remover o glicerol formado e proporcionar um incremento na formação de ésteres de etila em relação ao primeiro estágio. O desempenho do reator foi avaliado para diferentes tempos espaciais (10 a 16h), mantendo fixas as demais condições operacionais (substrato constituído de óleo de macaúba e etanol na razão molar óleo: etanol de 1:12 e temperatura de 50 ºC). O funcionamento do sistema foi comprovado quantitativamente para tempos espaciais no sistema igual a 16h, resultando em valores médios de produtividade de 36,7 ??2,4 mgéster.gmeio -1.h-1com perdas mínimas de matéria-prima (rendimento de transesterificação = 96,3 ??2,1%), sem redução de eficiência durante 25 dias de operação. As amostras de biodiesel purificadas apresentaram baixos teores de monoacilgliceróis (3,8%) ausência de diacilgliceróis e viscosidade cinemática média de 5,8 ± 0,3 mm2.s-1, atendendo as normas vigentes pela resolução ANP n°14/2012, que estabelece viscosidade cinemática do B100 na faixa entre 3,0 - 6,0 mm2.s-1. O biocatalisador foi estável quanto suas características morfológicas e catalíticas, revelando tempo de meia-vida de 423 h. Desta forma, a configuração do sistema reacional constituído por reator de leito fixo duplo estágio com a remoção simultânea de glicerol tem grande potencial para atingir elevado rendimento de transesterificação, aumentando a produtividade de biodiesel e consequentemente diminuindo o custo do processo industrial. Em geral, os resultados foram promissores e mostraram o potencial do óleo de macaúba para ser usado como matéria-prima para a produção de biodiesel em fluxo contínuo. / The present study aimed at assessing the potential of macaw palm oil as a raw material for the synthesis of biodiesel by enzymatic route. The proposed experimental was to develop a process that was able to transesterify the macaw palm oil with ethanol by immobilized lipase in packed bed reactor under continuous flow, in order to obtain biodiesel having suitable properties to be used as a fuel. The enzyme chosen for the development of this work was the microbial lipase from Burkholderia cepacia immobilized on non-commercial hybrid matrix SiO2-PVA. Single and two stages packed bed reactors were tested. Initially the influence of the reactor dimensions and ratio between height (l) and diameter (d) in the performance of the ethanolysis of macaw palm oil was assessed. Tests were carried out using two reactors (A and B) having different geometric relations: Reactor A (l = 55 mm and d = 15 mm) and Reactor B (l = 210 mm and d = 14) which corresponded to height/diameter (l/d = 3.7 and l/d = 15), respectively. Runs were performed continuously for 20 days using substrate containing oil to ethanol molar ratio of 1:12 in a solvent-free system and fixed space time of 14h. Data suggested that the dimensions of the packed column had a slight influence on the biodiesel production and under the conditions tested, the highest relation (l/d = 15) did not affect the fluid mass transfer throughout the reactor column. Under these conditions runs carried out in the reactor B provided average yields of 89.7 ± 4.8% and productivities of 40.4 ± 2.2 mgester?g-1?h-1. Following this, a two-stage packed bed reactor incorporating a column with cationic resin (Lewatit® GF 202) to remove the glycerol formed as by-product was used. The reactor performance was quantified for four different flow rates corresponded to spatial times from 10 to 16 h. For each condition, the influence of spatial times in the ethyl esters formation, transesterification yields and productivities were determined. The reactor operation was demonstrated for spatial time igual to 16 h, attaining ethyl ester formation of 58.1?2.1 wt%, transesterification yields of 96.3 ??2.1% and productivities of 36.7 ??2.4 mgester?g-1?h-1 with no significant reduction in the efficiency during 25 days. The purified samples showed residual levels of monoglycerides (3.8 wt %), absence of diglycerides and average viscosity values of 5.8 mm2/s which can be considered appropriated according to Brazilian resolution ANP n° 14/2012. The immobilized lipase on SiO2-PVA was found to be stable regarding its morphological and catalytic characteristics, showing half-life time (t1/2) higher than 423 h. Therefore, the continuous packed-bed reactor connected in series with simultaneous glycerol removal has a great potential to attain high level of transesterification yields, raising biodiesel productivity, consequently decreasing industrial process cost. Overall, the results were promising and showed the potential of macaw palm oil to be used as feedstock for biodiesel production under continuous flow.

O desenvolvimento industrial tem, como conseqüência, a maior geração de resíduos, muitos deles tóxicos aos seres vivos. Dentre esses, benzeno, tolueno e xilenos (BTX), derivados do petróleo, estão contaminando aqüíferos por acidentes no transporte e no armazenamento. Por esse motivo, diversas pesquisas têm sido realizadas buscando formas de biodegradar BTX. Esses trabalhos indicam que os principais fatores que podem influenciar a degradação biológica dos BTX são temperatura, pH, disponibilidade de nutrientes, concentração de tóxicos e diversidade de microrganismos. Visando contribuir com o estudo desses fatores, este trabalho teve por objetivo avaliar a influência do inóculo e de aceptores de elétrons no processo de degradação anaeróbia de BTX. Neste trabalho três inóculos foram pesquisados: 1- biomassa proveniente de reator anteriormente submetido à mistura de gasolina comercial e água; 2- biomassa proveniente de reator da estação de tratamento de esgoto da USP - São Carlos; 3- biomassa proveniente de reator tratando água residuária de abatedouro de aves. Os resultados obtidos comprovaram que a origem do inóculo foi fundamental na degradação anaeróbia de BTX, pois os inóculos apresentaram diferentes períodos de adaptação e porcentagens de degradação do tóxico. Depois de 93 dias de operação os inóculos 1, 2 e 3 apresentaram eficiência de remoção de BTX da ordem de 57%, 83% e 90%, respectivamente. O reator com o inóculo 3 foi submetido a condições metanogênica, sulfetogênica com presença e ausência de Ferro (III). Os resultados demonstraram que a degradação dos BTX foi influenciada pelas diferentes condições adotadas. A adição de Fe (III) melhorou a degradação dos BTX, do reator sob condições sulfetogênicas. / The industrial development has increased the generation of residues. Some of them are toxics and impact the environment. Benzene, toluene and xylenes (BTX), petroleum sub products, are examples of such toxic compounds. These compounds may contaminate aquifers as a result of accidents during transportation or of leakages of storage tanks. Several factors are reported to affect the biodegradation of BTX, such as: temperature, pH, availability of nutrients, concentration of toxics and diversity of microorganisms. This research aimed to study some of these factors, such as different inoculum sources and different electrons acceptors during BTX degradation processes in an horizontal-flow anaerobic immobilized biomass (HAIB) reactor. In this research three inocula were studied: 1- an adapted microbial community for BTX degradation; 2 - microorganisms collected from a pilot-scale UASB reactor treating domestic wastewater; and 3 - Microorganisms collected from an UASB treating poultry slaughterhouse industry wastewater. The results have shown that the inoculum sources were fundamental to the adaptation period for the toxic biodegradation, producing different BTX removal efficiencies. After 93 days of operation, the inocula 1, 2 and 3 showed BTX removal efficiency of 57, 83 and 90%, respectively. The inoculum 3 was submitted to conditions of methanogesis and sulfetogenesis in the presence and absence of Fe (III). The results demonstrated that BTX degradation was affected by the different conditions adopted, showing that the addition of Fe (III) improved biodegradation in the reactor under sulfate reduction condition.

The deformation behaviour and twinning mechanisms of commercially pure titanium alloys were investigated using complementary diffraction techniques and crystal plasticity modelling. The main motivation for conducting this investigation was to improve understanding of the deformation of titanium to help achieve the long term aim of reducing manufacturing and design costs. The deformation behaviour was characterised with tension, compression and channel die compression tests for three important variables: orientation; temperature from 25 C to 600 C; and composition for two contrasting alloys, CP-G1 and CP-G4. The experimental data used to characterise the behaviour and determine the mechanisms causing it were: textures determined by X-ray diffraction; twin area fractions for individual modes determined using electron back-scatter diffraction; and lattice strains measured by neutron diffraction. A strong effect of the orientation–stress state conditions on the flow curves (flow stress anisotropy) was found. The propensity for prism hai slip was the dominant cause of the behaviour – samples that were more favourably oriented for prism hai slip had lower flow stresses. Twinning was the most significant secondary deformation mode in the CP-G1 alloy but only had a minor effect on flow stress anisotropy in most cases. In the CP-G4 alloy twinning generally did not play a significant role indicating that hc + ai slip modes were significant in this alloy. Differences in the flow stress anisotropy between the two alloys were found to occur largely in the elasto-plastic transition and initial period of hardening. Modelling results indicated that larger relative resolved shear stress values for secondary deformation modes in the higher purity alloy increased the initial anisotropy. Decreasing flow stresses with increasing temperature were largely caused by a decrease in the critical resolved shear stress (CRSS) values for slip, but also by a decrease in the Hall-Petch parameter for slip. The propagation of twinning was found to be orientation dependent through a Schmid law in a similar way to slip – it was activated at a CRSS and hardened so that an increasing resolved shear stress was required for it to continue operating. The CRSS values determined for the individual twin modes were – 65MPa, 180MPa, 83MPa for {1012}, {1122} and {1011} twinning, respectively. Further, twinning was found to be temperature insensitive except when the ability to nucleate twins posed a significant barrier (for {1011} twinning). Also, the CRSS for {1012} twinning was clearly shown to increase with decreasing alloy purity. A thorough method for determining crystal plasticity modelling parameters based on experimental data was formulated. Additionally, twinning was modelled in a physically realistic manner influenced by the present findings using the visco-plastic self-consistent (VPSC) model. In particular: the activity of twinning decreased in a natural way due to greater difficulty in its operation rather than through an enforced saturation; and hardening or softening due to changes in orientation and dynamic Hall-Petch hardening were important. The rigorous modelling procedure gave great confidence in the key experimental findings.

Lobjet du présent travail est létude expérimentale et théorique de lhydrodynamique des écoulements dans des colonnes à garnissage et, plus particulièrement, lanalyse par tomographie à rayons X de la distribution spatiale des phases liquide et solide dans des lits fixes parcourus par un écoulement de liquide. La distribution des phases est observée à différents niveaux, depuis léchelle locale jusquà léchelle de la colonne dans son ensemble. Lintroduction permet tout dabord de rappeler les principales applications industrielles des colonnes à garnissage, ainsi que les caractéristiques particulières associées à chacune dentre elles. Lhydrodynamique des écoulements dans ce type dappareils résulte de phénomènes extrêmement complexes, intervenant à une échelle très petite. Cet état de choses a poussé les chercheurs à développer des modèles de plus en plus détaillés, dont la validation requiert une connaissance de plus en plus fine de la répartition des phases au sein des lits fixes. Lobtention de mesures à une échelle très locale savère donc indispensable. Après un bref rappel des différentes techniques de mesure plus ou moins locales qui ont été appliquées, dans le passé, à létude des écoulements dans des colonnes à garnissage, lensemble des techniques tomographiques, ainsi que leurs principaux champs dapplication sont présentés. Parmi ces applications, la tomographie à rayons X semble particulièrement bien adaptée, car elle permet daccéder à une cartographie complète de la distribution spatiale des différentes phases présentes dans une colonne à garnissage de relativement grandes dimensions. Le chapitre I présente en détail les bases de la technique expérimentale utilisée. La tomographie consiste à reconstruire limage dune section droite dun objet à partir de données de transmission, obtenues en illuminant cet objet sous un grand nombre dangles différents. Lalgorithme permettant de reconstruire les images à partir des données de projection est lalgorithme de rétro-projection filtrée, adapté à la géométrie du dispositif de radiographie (faisceau plan angulaire et détecteurs colinéaires équidistants). Cet algorithme, qui est le plus utilisé en pratique, a dû être modifié pour tenir compte dimperfections géométriques existant au niveau du dispositif de mesure. Le chapitre II décrit linstallation expérimentale, qui comprend le tomographe à rayons X, la colonne à garnissage et leurs éléments périphériques respectifs. Le tomographe consiste en un dispositif de radiographie (source de rayons X et détecteur linéaire) fixé sur un manipulateur. Le pilotage de linstallation, ainsi que lacquisition des données expérimentales sont réalisés grâce à un pupitre de commande et à un P.C. Le dispositif de tomographie permet de réaliser des images de sections droites dune colonne à garnissage, irriguée grâce à un dispositif dalimentation et dévacuation des fluides. Après une description relativement détaillée de tous ces éléments, le mode opératoire suivi pour la réalisation des différentes mesures expérimentales est présenté. Dans les chapitres III à V sont regroupés les différents résultats expérimentaux, ainsi que les discussions et commentaires sy rapportant. Le chapitre III présente les différents essais réalisés en vue de valider le dispositif de tomographie. Dans ce but, des objets de forme et de taille connues ont été radiographiés. La confrontation des images reconstruites et des objets originaux permet deffectuer cette validation, mais également dapprécier la résolution de la technique tomographique de mesure. Le chapitre IV expose les résultats obtenus sur base des images de sections droites de la colonne sèche. Dans un premier temps, les différentes opérations effectuées sur les images, après leur reconstruction, sont décrites. Ces opérations ont pour but de donner une signification physique réelle aux valeurs des pixels composant les images, mais également daméliorer la représentation graphique de ces dernières. Une des premières grandeurs calculées sur les sections reconstruites est la fraction de vide de lempilage. Les valeurs de porosité ainsi calculées sont comparées à dautres valeurs obtenues expérimentalement, ainsi quaux valeurs annoncées par les fabricants dempilages. Une dimension caractéristique, propre à chacun des types dempilage, est ensuite calculée grâce à lapplication de différentes méthodes comme lanalyse de lentropie de configuration, lanalyse de la distribution de la fraction de solide ou encore lanalyse de la fonction dautocorrélation. La dimension caractéristique ainsi déterminée permet daccéder à la taille des cellules élémentaires susceptibles de représenter la morphologie de la phase solide dans le cadre dune modélisation des phénomènes hydrodynamiques intervenant au sein du lit fixe. Après une brève conclusion récapitulative, la dernière partie du chapitre IV est consacrée à la visualisation des différentes échelles caractéristiques présentes dans les images analysées. Le chapitre V décrit les résultats obtenus sur base des images de sections droites de la colonne irriguée. Dans un premier temps, les images obtenues sur des sections irriguées font lobjet dune analyse purement qualitative. Cette analyse permet dobserver linfluence exercée par le distributeur de liquide sur la distribution du liquide au sein de sections droites situées à différentes hauteurs au sein de la colonne, pour différentes valeurs du débit de liquide. Elle permet également dobserver la corrélation existant entre les distributions des phases liquide et solide au sein de la colonne. Ensuite, les valeurs globales de la rétention de liquide calculées sur base des valeurs des pixels composant les images reconstruites sont confrontées à des valeurs de rétention obtenues par dautres méthodes, expérimentales ou théoriques, afin de valider les résultats obtenus par tomographie. Dans ce but, des comparaisons sont effectuées avec des résultats expérimentaux présentés dans la littérature, avec des valeurs de rétentions mesurées par essais de traceur, ainsi quavec des valeurs calculées grâce à des corrélations proposées dans la littérature et plus particulièrement grâce à la corrélation issue dun modèle découlement en canaux. Un modèle hydrodynamique basé sur une approche probabiliste est ensuite utilisé pour modéliser lhydrodynamique au sein de la colonne à garnissage. Cette approche permet non seulement de rendre compte de lévolution des valeurs globales de la rétention de liquide, mais également de modéliser la distribution des valeurs locales de la vitesse du liquide dans les différentes sections de la colonne à garnissage. Pour terminer, la conclusion résume lensemble des résultats issus de la présente étude, avant de lancer quelques pistes pour des travaux de recherche à venir.

Crystallographic texture in polycrystalline materials are known to play an important role in tailoring suitable properties for various technological applications. In addition, the evolution of texture provides a profound basis to develop scientific understanding of physical processes occurring in the material during deformation and annealing. Between the two, the understanding of deformation texture is much broader. However, certain issues pertaining to the evolution of deformation texture evolution are yet to be explored or not uniquely agreed upon. A few notable examples are the effects of extreme grain sizes and strain rates. Moreover, most of the studies are pertaining to single phase metals and alloys. While many engineering alloys consist of two phase microstructures, the effect of second phase in the microstructure on the evolution of texture in the individual phases has not been studied in a comprehensive manner. The present thesis is an attempt to addresses these issues in a more generic manner. The studies have been specifically aimed at examining the aforesaid issues in the close packed Face Centre Cubic (FCC) and Hexagonal Close Packed (HCP) metals and alloys. In brief, this thesis addresses the following problems pertaining to deformation texture: (i) the effect of extreme grain sizes, (ii) the effect of extreme strain rates and (iii) the effect of a second ductile phase. Chapter 1 of the thesis gives a detailed survey of literature pertaining to the evolution of deformation textures in different metals and alloys, while chapter 2 includes the details of the experimental techniques and simulation procedures, which are mostly common for the entire work. The issue of grain size is addressed in chapter 3. In the present investigation, the evolution of deformation texture in nickel (FCC) and titanium (HCP) with the extreme grain sizes (nanometre and millimetre) has been studied. Nanocrystalline nickel with the grain size ~ 20 nm was obtained by pulse electro-deposition while the other extreme of the grain size in nickel was obtained by annealing of a cold rolled sheet at 1373 K. The rolling texture in nanocrystalline nickel had a higher volume fraction of Brass component than in nickel with normal grain size. These results have been explained on the basis of inhibition of cross slip in small grain sizes and the operation of planar slip. This has been validated by viscoplastic self-consistent simulations. The texture of coarse grain nickel samples (typified as oligocrystalline, owing to the lesser number of grains in the thickness direction) also had higher Brass component like the nanocrystalline sample. A detailed analysis was performed by examining misorientation development in the grain interior and in the vicinity of the grain boundaries. The similarity at the two extreme length scales has been explained on the basis of lower “Grain Boundary Affected Zone” at the extreme length scales. To examine the effect of grain size in the case of HCP materials, commercially pure titanium with ultra-fine (500 nm) and normal grain size (~50 μm), was investigated. A monotonic evolution of texture was observed in the former, which has been attributed to the absence of twinning, a situation that could arise due to the lack of coordinated movement of twinning partials in the sub-micron grain size regime. Thus, a reasonable understanding of the evolution of deformation texture in hitherto unexplored regime of grain sizes was developed for the two materials. The chapter 4 of the thesis is dedicated to the study of strain rate effects in both FCC and HCP materials. The issue of strain rate has been addressed by two ways: (a) deforming the materials at extreme strain rates, namely 10-3 s-1 to 10+3 s-1 under compression up to a reasonable strain, and (b) deforming the materials under torsion within a reasonable range of strain rates, but up to large strains. In this case, in addition to nickel, copper was also investigated owing to the different strain hardening behaviour of the two materials. The compression texture in nickel and copper was characterized by the presence of <101> component at low strain rates. At high strain rate, ~10+3 s-1, there was a decrease in the intensity of the <101> component for nickel but it strengthened for copper. This has been explained on the basis of continuous dynamic recrystallization in copper. The torsion texture evolution in nickel and copper was similar at low strain rate (10-3 s-1) and was characterized by the presence of important shear texture components. At high strain rate (1 s-1), texture weakened for nickel, while for copper a rotated cube component was observed which has been attributed to dynamic recrystallization. The effect of strain rate was studied more comprehensively in hexagonal titanium by adding one more variable, that is, the initial texture. Extreme strain rates were imparted using static and dynamic compression tests. It was found that different initial textures led to different mechanical response in terms of yield strength and strain hardening as well as microstructural response in terms of twin fractions. The samples deformed at high strain rate showed increased twinning that led to some scatter in the texture components compared to low strain rate deformed samples. VPSC simulations were able to successfully capture the evolution of texture as well as microstructural evolution in terms of twin activity in the deformed samples at the extreme strain rates. Torsion tests on titanium at different strain rates indicated evolution of inhomogeneous nature of fibre texture components with increase in strain rate. Thus, weakening of texture was observed irrespective of the strain path (compression or torsion) and crystal structure (FCC or HCP) unless additional restoration mechanism like recrystallization (continuous or discontinuous) intervened. In chapter 5, the evolution of rolling texture in two phase FCC + BCC (Ni-Fe-Cr alloys) and HCP + BCC (Ti-13Nb-13Zr ) alloys has been studied. This study was aimed at examining the effect of second deforming phase on the texture evolution in the primary phase. The effect of various parameters like volume fraction and morphology of the second phase on deformation texture evolution was studied experimentally as well as by VPSC simulations. A reduction in the Brass component of texture was observed in the austenite phase due to the presence of harder ferrite phase while a characteristic rolling texture evolved in the ferrite phase. It has been established that the softer austenite phase carried maximum strain at low volume fractions of ferrite while the harder ferrite phase carried the maximum strain at higher volume fractions of ferrite. In case of the two phase HCP+BCC alloy Ti-13Nb-13Zr, both the hexagonal α and the cubic β phases showed a characteristic rolling texture irrespective of two different morphologies. For both the equiaxed and colony microstructures, the softer β phase carried the maximum strain. VPSC simulations were able to model the deformation texture evolution as well as microstructural parameters like strain partitioning and twin fraction satisfactorily for both the microstructural conditions. It was found that the deformation mechanism in one phase could be affected by the presence of the second phase and that a characteristic change in deformation texture could be produced in the presence of the second phase. Thus, a comprehensive perspective has been developed pertaining to the evolution of texture in FCC and HCP phases in the presence of a second ductile phase. The overall findings of the three investigations carried out for the thesis are summarised in chapter 6.

In this work, flow through synthetic arrangements of contacting spheres is studied as a model problem for porous media and packed bed type flows. Direct numerical simulations are performed for moderate pore Reynolds numbers in the range, 10 ≤ Re ≤ 600, where non-linear porescale flow features are known to contribute significantly to macroscale properties of engineering interest. To first choose and validate appropriate computational models for this problem, the relative performance of two numerical approaches involving body conforming and non-conforming grids for simulating porescale flows is examined. In the first approach, an unstructured solver is used with tetrahedral meshes, which conform to the boundaries of the porespace. In the second approach, a fictitious domain formulation (Apte et al., 2009. J Comput. Phys. 228 (8), 2712-2738) is used, which employs non-body conforming Cartesian grids and enforces the no-slip conditions on the pore boundaries implicitly through a rigidity constraint force. Detailed grid convergence studies of both steady and unsteady flow through prototypical arrangements of spheres indicate that for a fixed level of uncertainty, significantly lower grid densities may be used with the fictitious domain approach, which also does not require complex grid generation techniques. Next, flows through both random and structured arrangements of spheres are simulated at pore Reynolds numbers in the steady inertial ( 10 ≲ Re ≲ 200) and unsteady inertial (Re ≈ 600) regimes, and used to analyze the characteristics of porescale vortical structures. Even at similar Reynolds numbers, the vortical structures observed in structured and random packings are remarkably different. The interior of the structured packings are dominated by multi-lobed vortex rings structures that align with the principal axes of the packing, but perpendicular to the mean flow. The random packing is dominated by helical vortices, elongated parallel to the mean flow direction. The unsteady dynamics observed in random and structured arrangements are also distinct, and are linked to the behavior of the porescale vortices. Finally, to investigate the existence and behavior of transport barriers in packed beds, a numerical tool is developed to compute high resolution finite-time Lyapunov exponent (FTLE) fields on-the-fly during DNS of unsteady flows. Ridges in this field are known to correspond to Lagrangian Coherent Structures (LCS), which are invariant barriers to transport and form the skeleton of time dependent Lagrangian fluid motion. The algorithm and its implementation into a parallel DNS solver are described in detail and used to explore several flows, including unsteady inertial flow in a random sphere packing. The resulting FTLE fields unambiguously define the boundaries of dynamically distinct porescale features such as counter rotating helical vortices and jets, and capture time dependent phenomena including vortex shedding at the pore level. / Graduation date: 2013

During the last few decades, concerns about water shortages and pollution have increased. Consequently, environmental legislations and regulations for wastewater discharge have been issued. The objective of this work was to contribute in developing an efficient dsorbent for removing heavy metal ions from wastewater. The thesis focused on evaluating amine-modified SBA-15 as copper and other heavy metal ions adsorbent, by determining a variety of adsorptive properties with the aim of gaining a deep understanding of its behavior and to outline its advantages and limitations. The influence of synthesis conditions on the mesostructural stability of the resultant materials after different water treatments was systematically investigated. N2 adsorption results indicated that the material prepared via co-condensation and aged at 100 ºC was not stable and lost its ordered mesoporous structure after contacting water even at room temperature. Aging at 130 ºC and addition of inorganic salts resulted in materials that maintained their mesporous structure under different water treatments. The material synthesized in the presence of KCl was used as adsorbent for the rest of the thesis work. It was shown that the structural collapse observed in amine-modified SBA-15 prepared by conventional method when contacted with aqueous solutions is associated with the drying process, and not the treatment itself. This structural collapse was avoided by replacing water with more volatile liquids such as acetone, before drying. Amino-functionalized SBA-15 was tested for the removal of copper ions from aqueous solutions under different temperatures, pH, initial concentrations and agitation speeds. The obtained results indicated that the amino-functionalized SBA-15 was very efficient and equilibrium was achieved in less than 30 min at room temperature. The adsorption capacity increased dramatically with increasing temperature, initial copper concentration and pH. Under suitable conditions, the material exhibited high adsorption capacity even at very low copper concentration. To further investigate the effect of dsorption parameters, a 24 factorial design experiments were used to screen the factors affecting the copper removal efficiency. All the parameters main effects were significant within a 95 % confidence level. Surface composite design was used to develop a reliable model representing the adsorption process. The statistical tests used proved the adequacy of the second order model. Optimization of the factors levels was carried out and the recommended optimum conditions are: copper concentration of 20 mg/L, adsorbent/solution ratio of 1.57 g/L, pH of 6.5, and T = 294 K with 95% copper removal. The effect of regeneration conditions was investigated after three adsorption–desorption cycles, under different batchwise regeneration conditions. Using a composite surface design methodology, the effect of the regeneration conditions on the performance of the adsorbent was investigated. It was found that all the studied parameters have a statistically significant influence on the working dsorption capacity. With respect to structural properties and amine content, none of the factors was found to be significant. Regeneration using EDTA was found to be more efficient than acid treatment. Amino-functionalized SBA-15 was studied as potential absorbent for Cd2 +, Co2 +, Cu2 +, Zn2 +, Pb2 +, Ni2 +, Al3+ and Cr3 +. The adsorption capacity and selectivity of the material were investigated in single and multi-metal solutions. Using very dilute solutions, i.e., 10 ppm, more than 95% of cations were removed, except for Co2+ and Cr3 +, indicatingthe high sensitivity of the current adsorbent. The adsorption capacities in multi-metal solutions were lower than in single-metal ones because of competition between metallic elements for the amine groups. The adsorbent was not affected in the presence of sodium, potassium, and calcium, indicating that the ionic strength does not affect the adsorption properties. Application of this material to remove copper in tap water, river water, and electroplating wastewater was shown to be successful. Dynamic experiments were carried out on the adsorption of copper ions in a laboratory packed-bed of amine-modified SBA-15. Breakthrough curves were analyzed at different flowrates and after two adsorption-desorption cycles. Furthermore, a model based on mass balance was developed and tested for predicting the breakthrough curves under different experimental conditions used. The results suggested that the developed model was in good agreement with the experimental data. Bed regeneration was performed by circulating 0.2 M EDTA solution through the column for 30 min. Résumé Durant les quelques dernières décennies, les préoccupations concernant les pénuries d'eau et la pollution en général ont augmenté. Par conséquent, des législations et des réglementations environnementales pour les rejets d'eaux usées ont été introduites. L'objectif de ce travail était de contribuer au développement d'un adsorbant efficace pour éliminer les ions de métaux lourds des eaux usées. Cette thèse porte sur l'évaluation de SBA-15 modifiée avec des amines comme adsorbant pour le cuivre et d'autres ions de métaux lourds par la détermination d'une multitude de propriétés d'adsorption dans le but d'acquérir une profonde compréhension de son comportement et d’identifier ses avantages et ses limites. L'influence des conditions de synthèse sur la stabilité des matériaux mésoporeux obtenus après différents traitements a été étudié de façon systématique. Les résultats d'adsorption de N2 ont indiqué que le matériel préparé par co-condensation et vieilli à 100 °C n'était pas stable et a perdu sa structure mésoporeuse ordonnée après avoir été en contact avec l'eau même à température ambiante. Le vieillissement à 130 °C, avec ajout de sels inorganiques, a abouti à des matériaux qui ont maintenu leur structure mésoporeuse sous différents traitements en présence d'eau. Le matériau synthétisé en présence de KCl a été utilisé comme adsorbant pour le reste du travail de cette thèse. Il a été démontré que l'effondrement de la structure observé dans la SBA-15 modifiée aux amines, préparée par la méthode conventionnelle en contact avec des solutions aqueuses est associé avec le processus de séchage, et non le traitement lui-même. Cet effondrement de structure a été évité en remplaçant l'eau avec des liquides plus volatils tels que l'acétone, avant le séchage. La SBA-15 amino-fonctionnalisée a été testée pour l'élimination des ions de cuivre des solutions aqueuses à différentes températures, pH, concentrations initiales et vitesses d'agitation. Les résultats obtenus ont indiqué que la SBA-15 amino-fonctionnalisée était très efficace et l'équilibre a été atteint en moins de 30 min à température ambiante. La capacité d'adsorption a considérablement augmenté avec la température, la concentration initiale de cuivre et le pH. Sous des conditions appropriées, le matériau a manifesté une grande capacité d'adsorption, même à des concentrations très faibles en cuivre. Afin d’étudier l'effet des paramètres d'adsorption, un plan factoriel de 24 expériences a été utilisé pour dépister les facteurs affectant l'efficacité d'élimination du cuivre. Tous les effets principaux des paramètres étaient importants à 95% de niveau de confiance. La méthodologie de la surface composite a été utilisée pour développer un modèle fiable qui représente le processus d'adsorption. Les tests statistiques utilisés ont prouvé la pertinence du modèle de second ordre. L’optimisation des niveaux des facteurs a été effectuée et les conditions optimales recommandées sont: la concentration en cuivre de 20 mg/L, le rapport adsorbant/solution de 1.57 g/L, pH de 6.5 et T = 294 K pour l'élimination de 95% de cuivre. L'effet des conditions de régénération a été étudié après trois cycles d'adsorption-désorption, sous différentes conditions de régénération. En utilisant la méthodologie de la surface composite, l'effet des conditions de régénération sur la performance de l'adsorbant a été étudié. Il a été constaté que tous les paramètres étudiés ont une influence statistiquement significative sur la capacité de travail d'adsorption. En ce qui concerne les propriétés structurelles et la teneur en amine, aucun des facteurs n’a été jugé significatif. La régénération à l'aide d'EDTA a été jugée plus efficace que le traitement acide. La SBA-15 amino-fonctionnalisée a été étudiée comme absorbant potentiel de Cd2+, Co2+, Cu2+, Zn2+, Pb2+, Ni2+, Al3+ and Cr3+. La capacité d'adsorption et la sélectivité du matériau ont été étudiées dans des solutions mono- et multi-métalliques. En utilisant des solutions très diluées, soit 10 ppm, plus de 95% de cations ont été enlevés, sauf pour le Co2+ et Cr3+, indiquant la forte sensibilité de l'adsorbant. Les capacités d'adsorption dans les solutions multi-métalliques étaient inférieures à celles des solutions mono-métalliques en raison de la concurrence entre les éléments métalliques pour les groupes amine. L'adsorbant n'a pas été affecté par la présence de sodium, de potassium et de calcium, ce qui indique que la force ionique n'affecte pas les propriétés d'adsorption. L’usage avec succès de ce matériau pour éliminer le cuivre dans l'eau de robinet, l’eau de rivière et les eaux usées de galvanoplastie a été démontré. Des expériences dynamiques ont été réalisées sur l'adsorption des ions de cuivre par la SBA-15 amine-modifiée sur une colonne à lit fixe de laboratoire. Les courbes de perçage ont été analysées à des débits différents et après deux cycles d'adsorption-désorption. De plus, un modèle basé sur le bilan de matière a été développé et testé pour prédire les courbes de perçage sous les différentes conditions expérimentales utilisées. Les résultats suggèrent que le modèle développé est en bon accord avec les données expérimentales. La régénération du lit a été réalisée en faisant circuler une solution EDTA à 0.2 M à travers la colonne pendant 30 min.

The physiological benefits of flaxseed against pathological disturbances, such as cancers and heart diseases, are mainly attributed to its high lignan content. This study (Experiment 1) examined the application of pressurized low polarity water (PLPW) for extraction of lignans, proteins and carbohydrates from defatted flaxseed meal. Key processing conditions included temperature (130, 160, 190°C), solvent pH (4, 6.5 and 9), solvent to solid ratio (S/S) (90, 150 and 210 mL/g) and introduction of co-packing material (0 and 3 g glass beads). The addition of 3 g glass beads as co-packing material facilitated extraction by enhancing surface contact between the liquid and solid thus shortening extraction time. Elevated temperature accelerated the extraction rate by increasing the solid diffusion coefficient thereby reducing the extraction time. The maximum yield of lignans (99 %) was obtained at temperatures ranging from 160°C to 190°C, with solvent volume of 180 mL (90 mL/g meal) at pH 9. Optimal conditions for protein extraction (70 %) were pH 9, extraction volume of 420 mL (210 mL/g meal) and 160°C. Total carbohydrates yield was maximized at 50% recovery at pH 4 and 160°C with 420 mL solvent (210 mL/g meal). Increased temperature accelerated extraction, thus reducing solvent volume and time to reach equilibrium. For the extraction of proteins, however, a temperature of 130-160°C is recommended, as proteins are vulnerable to thermal degradation due to heat decomposition. The effects of flow rate and geometric dimensions for extraction of lignans and other flaxseed meal bioactives were further investigated in Experiment 2, based on the variables optimized in the previous experiment. Defatted flaxseed meal was extracted with pH 9 buffered water with meal to co-packing glass beads ratio of 1:1.5 at 5.2 MPa (750 psi) and 180°C. The aqueous extracts were analyzed for lignan, protein and carbohydrate using HPLC and colorimetric methods. The optimal extraction yields for lignan, protein and carbohydrate were found at flow rates of 1 to 2 mL/min with bed depth between 20 and 26 cm and a S/S ratio of 40 to 100 mL/g. The combination of low flow rate and high bed depth allowed the use of lower S/S ratio with reduced total solvent volume consumption. This study also evaluated the mass transfer kinetics governing the process of lignan extraction from flaxseed meal in a fixed bed extraction cell. Diffusion of solute into the continuously flowing solvent was mainly responsible for the mass transfer mechanism as flow rate did not increase proportionally with the yield and rate of extraction. The extraction kinetics were studied on the basis of two approaches: Fick’s diffusion equation and a two-site exponential kinetic model. The proposed two-site exponential kinetic model corresponding to the two-stage extraction (rapid and slow phases) successfully described the experimental data. Diffusivities attained from Fick’s diffusion model ranged from 2 x 10-13 to 9 x 10-13 m2s-1 while mass transfer coefficients were between 4.5 x 10-8 and 2.3 x 10-7 ms-1 for extraction of lignans at 180°C, pH 9 with 1:1.5 meal to co-packing material ratio. / February 2007

During the last few decades, concerns about water shortages and pollution have increased. Consequently, environmental legislations and regulations for wastewater discharge have been issued. The objective of this work was to contribute in developing an efficient dsorbent for removing heavy metal ions from wastewater. The thesis focused on evaluating amine-modified SBA-15 as copper and other heavy metal ions adsorbent, by determining a variety of adsorptive properties with the aim of gaining a deep understanding of its behavior and to outline its advantages and limitations. The influence of synthesis conditions on the mesostructural stability of the resultant materials after different water treatments was systematically investigated. N2 adsorption results indicated that the material prepared via co-condensation and aged at 100 ºC was not stable and lost its ordered mesoporous structure after contacting water even at room temperature. Aging at 130 ºC and addition of inorganic salts resulted in materials that maintained their mesporous structure under different water treatments. The material synthesized in the presence of KCl was used as adsorbent for the rest of the thesis work. It was shown that the structural collapse observed in amine-modified SBA-15 prepared by conventional method when contacted with aqueous solutions is associated with the drying process, and not the treatment itself. This structural collapse was avoided by replacing water with more volatile liquids such as acetone, before drying. Amino-functionalized SBA-15 was tested for the removal of copper ions from aqueous solutions under different temperatures, pH, initial concentrations and agitation speeds. The obtained results indicated that the amino-functionalized SBA-15 was very efficient and equilibrium was achieved in less than 30 min at room temperature. The adsorption capacity increased dramatically with increasing temperature, initial copper concentration and pH. Under suitable conditions, the material exhibited high adsorption capacity even at very low copper concentration. To further investigate the effect of dsorption parameters, a 24 factorial design experiments were used to screen the factors affecting the copper removal efficiency. All the parameters main effects were significant within a 95 % confidence level. Surface composite design was used to develop a reliable model representing the adsorption process. The statistical tests used proved the adequacy of the second order model. Optimization of the factors levels was carried out and the recommended optimum conditions are: copper concentration of 20 mg/L, adsorbent/solution ratio of 1.57 g/L, pH of 6.5, and T = 294 K with 95% copper removal. The effect of regeneration conditions was investigated after three adsorption–desorption cycles, under different batchwise regeneration conditions. Using a composite surface design methodology, the effect of the regeneration conditions on the performance of the adsorbent was investigated. It was found that all the studied parameters have a statistically significant influence on the working dsorption capacity. With respect to structural properties and amine content, none of the factors was found to be significant. Regeneration using EDTA was found to be more efficient than acid treatment. Amino-functionalized SBA-15 was studied as potential absorbent for Cd2 +, Co2 +, Cu2 +, Zn2 +, Pb2 +, Ni2 +, Al3+ and Cr3 +. The adsorption capacity and selectivity of the material were investigated in single and multi-metal solutions. Using very dilute solutions, i.e., 10 ppm, more than 95% of cations were removed, except for Co2+ and Cr3 +, indicatingthe high sensitivity of the current adsorbent. The adsorption capacities in multi-metal solutions were lower than in single-metal ones because of competition between metallic elements for the amine groups. The adsorbent was not affected in the presence of sodium, potassium, and calcium, indicating that the ionic strength does not affect the adsorption properties. Application of this material to remove copper in tap water, river water, and electroplating wastewater was shown to be successful. Dynamic experiments were carried out on the adsorption of copper ions in a laboratory packed-bed of amine-modified SBA-15. Breakthrough curves were analyzed at different flowrates and after two adsorption-desorption cycles. Furthermore, a model based on mass balance was developed and tested for predicting the breakthrough curves under different experimental conditions used. The results suggested that the developed model was in good agreement with the experimental data. Bed regeneration was performed by circulating 0.2 M EDTA solution through the column for 30 min. Résumé Durant les quelques dernières décennies, les préoccupations concernant les pénuries d'eau et la pollution en général ont augmenté. Par conséquent, des législations et des réglementations environnementales pour les rejets d'eaux usées ont été introduites. L'objectif de ce travail était de contribuer au développement d'un adsorbant efficace pour éliminer les ions de métaux lourds des eaux usées. Cette thèse porte sur l'évaluation de SBA-15 modifiée avec des amines comme adsorbant pour le cuivre et d'autres ions de métaux lourds par la détermination d'une multitude de propriétés d'adsorption dans le but d'acquérir une profonde compréhension de son comportement et d’identifier ses avantages et ses limites. L'influence des conditions de synthèse sur la stabilité des matériaux mésoporeux obtenus après différents traitements a été étudié de façon systématique. Les résultats d'adsorption de N2 ont indiqué que le matériel préparé par co-condensation et vieilli à 100 °C n'était pas stable et a perdu sa structure mésoporeuse ordonnée après avoir été en contact avec l'eau même à température ambiante. Le vieillissement à 130 °C, avec ajout de sels inorganiques, a abouti à des matériaux qui ont maintenu leur structure mésoporeuse sous différents traitements en présence d'eau. Le matériau synthétisé en présence de KCl a été utilisé comme adsorbant pour le reste du travail de cette thèse. Il a été démontré que l'effondrement de la structure observé dans la SBA-15 modifiée aux amines, préparée par la méthode conventionnelle en contact avec des solutions aqueuses est associé avec le processus de séchage, et non le traitement lui-même. Cet effondrement de structure a été évité en remplaçant l'eau avec des liquides plus volatils tels que l'acétone, avant le séchage. La SBA-15 amino-fonctionnalisée a été testée pour l'élimination des ions de cuivre des solutions aqueuses à différentes températures, pH, concentrations initiales et vitesses d'agitation. Les résultats obtenus ont indiqué que la SBA-15 amino-fonctionnalisée était très efficace et l'équilibre a été atteint en moins de 30 min à température ambiante. La capacité d'adsorption a considérablement augmenté avec la température, la concentration initiale de cuivre et le pH. Sous des conditions appropriées, le matériau a manifesté une grande capacité d'adsorption, même à des concentrations très faibles en cuivre. Afin d’étudier l'effet des paramètres d'adsorption, un plan factoriel de 24 expériences a été utilisé pour dépister les facteurs affectant l'efficacité d'élimination du cuivre. Tous les effets principaux des paramètres étaient importants à 95% de niveau de confiance. La méthodologie de la surface composite a été utilisée pour développer un modèle fiable qui représente le processus d'adsorption. Les tests statistiques utilisés ont prouvé la pertinence du modèle de second ordre. L’optimisation des niveaux des facteurs a été effectuée et les conditions optimales recommandées sont: la concentration en cuivre de 20 mg/L, le rapport adsorbant/solution de 1.57 g/L, pH de 6.5 et T = 294 K pour l'élimination de 95% de cuivre. L'effet des conditions de régénération a été étudié après trois cycles d'adsorption-désorption, sous différentes conditions de régénération. En utilisant la méthodologie de la surface composite, l'effet des conditions de régénération sur la performance de l'adsorbant a été étudié. Il a été constaté que tous les paramètres étudiés ont une influence statistiquement significative sur la capacité de travail d'adsorption. En ce qui concerne les propriétés structurelles et la teneur en amine, aucun des facteurs n’a été jugé significatif. La régénération à l'aide d'EDTA a été jugée plus efficace que le traitement acide. La SBA-15 amino-fonctionnalisée a été étudiée comme absorbant potentiel de Cd2+, Co2+, Cu2+, Zn2+, Pb2+, Ni2+, Al3+ and Cr3+. La capacité d'adsorption et la sélectivité du matériau ont été étudiées dans des solutions mono- et multi-métalliques. En utilisant des solutions très diluées, soit 10 ppm, plus de 95% de cations ont été enlevés, sauf pour le Co2+ et Cr3+, indiquant la forte sensibilité de l'adsorbant. Les capacités d'adsorption dans les solutions multi-métalliques étaient inférieures à celles des solutions mono-métalliques en raison de la concurrence entre les éléments métalliques pour les groupes amine. L'adsorbant n'a pas été affecté par la présence de sodium, de potassium et de calcium, ce qui indique que la force ionique n'affecte pas les propriétés d'adsorption. L’usage avec succès de ce matériau pour éliminer le cuivre dans l'eau de robinet, l’eau de rivière et les eaux usées de galvanoplastie a été démontré. Des expériences dynamiques ont été réalisées sur l'adsorption des ions de cuivre par la SBA-15 amine-modifiée sur une colonne à lit fixe de laboratoire. Les courbes de perçage ont été analysées à des débits différents et après deux cycles d'adsorption-désorption. De plus, un modèle basé sur le bilan de matière a été développé et testé pour prédire les courbes de perçage sous les différentes conditions expérimentales utilisées. Les résultats suggèrent que le modèle développé est en bon accord avec les données expérimentales. La régénération du lit a été réalisée en faisant circuler une solution EDTA à 0.2 M à travers la colonne pendant 30 min.

In this diploma work, the absorption of CO2 in different liquid solutions was studied by gas absorption in a randomly packed column. To characterize the absorption a few experiments with SO2 absorption were made.The report has resulted due to the large amounts of carbon dioxide released into the atmosphere, mainly from fossil-fired power plants. To reduce these emissions, carbon dioxide can be separated from flue gas by different techniques such as CO2 absorption with ammonia. The work consists of a theoretical and a laboratory part of measurements and calculations. In the experimental part a system of absorption and associated test equipment was constructed. Different liquid solutions of pure water, potassium carbonate solution and ammonia in various concentrations were used to catch carbon dioxide by countercurrent absorption. Also SO2 was absorbed in the potassium carbonate solution to determine the gas film constant. The absorption efficiency of CO2 ranged from a few percent in the experiment with water to up to 7% with potassium carbonate solution. The CO2 absorption of ammonia varied with concentration and gave a separation of between 12 and 94%. Ammonia tests were made at both 10 and 20 °C. In general, a higher CO2-capture at 20 °C was obtained as confirmed by theory. / I detta examensarbete har absorptionseffektivitet av CO2 hos olika vätskelösningar undersökts genom gasabsorption i en slumpmässigt packad kolonn. För att karakterisera absorptionen absorberades även SO2 i några experiment. Rapporten är utförd med anledning av de stora mängder koldioxid som släpps ut i atmosfären, främst från fossileldade kraftverk. För att minska dessa utsläpp kan koldioxiden avskiljas från rökgaserna genom olika tekniker t.ex. genom CO2-absorption med ammoniak. Arbetet består av en teoridel och en laborativ del med mätningar och beräkningar. I den experimentella delen konstruerades ett system med en absorptionskolonn och tillhörande mätutrustning. Olika vätskelösningar bestående av rent vatten, kaliumkarbonatlösning och ammoniak i olika koncentrationer användes till att ta upp koldioxid genom motströms absorption. Även SO2 absorberades i kaliumkarbonatlösning för att bestämma gasfilmkonstanten. Absorptionsgraden av CO2 varierade från några få procent i försöket med vatten upp till 7 % med kaliumkarbonatlösningen. CO2-absorptionen av ammoniak varierade med koncentrationen och gav en avskiljning på mellan 12 och 94 %. Ammoniakförsöken gjordes med både vid 10 och 20 °C. Generellt erhölls en bättre CO2-avskiljning vid 20°C, vilket bekräftas av teorin.