Woven textile fabrics were designed and constructed from hydrophilic and hydrophobic spun yarns to give planar substrates containing amphiphilic microchannels with defined orientations and locations. Polypropylene fibers were spun to give hydrophobic yarns, and the hydrophilic yarns were spun from a poly(ethylene terephthalate) copolyester. Water wicking rates into the fabrics were measured by video microscopy and longitudinal wicking tests from single drops and from reservoirs. Intra-yarn microchannels in the hydrophilic polyester yarns were shown to selectively transport aqueous fluids, with the flow path governed by the placement of the hydrophilic yarns in the fabric. Simultaneous wicking of an aqueous and hydrocarbon fluid into the hydrophilic and hydrophobic microchannels of an amphiphilic fabric was successfully demonstrated. The high degree of interfacial contact and micron-scale diffusion lengths of such co-flowing immiscible fluid streams inside amphiphilic fabrics suggest potential applications as highly scalable and affordable microcontactors for industrial liquid-liquid extractions. The efficiency of liquid-liquid extractions carried out with the amphiphilic fabrics was evaluated. Solvent extraction efficiencies were shown to reach up to ~98%.

D. Tech. Chemical, Metallurgical and Materials Engineering / This study provides experimental data and new perspectives on selective precipitation of platinum group metals (PGMs) in the presence of base metals while at the same time reviewing the mass transfer characteristics and models associated with metal sulphides precipitation in liquid-liquid and gas-liquid systems. In this study, the objective was to investigate and validate the concept of selective precipitation of platinum from chloride media using sulphur-bearing liquids or gases.

A computational fluid dynamics model has been developed to examine the separation of an oil film from a spherical oil-coated particle falling through quiescent water due to gravity. Using this model, the separation process was studied as a function of the viscosity ratio of oil to water, R, and the ratio of viscous forces to surface tension, represented by the Capillary number Ca. The governing equations of this flow-induced motion are derived in a non-inertial spherical coordinate system, and discretized using a finite volume approach. The Volume-of-Fluid method is used to capture the oil/water interface. The model predicts two mechanisms for oil separation: at R less than 1, the shear difference between the particle/oil interface and the oil/water interface is not significant and Ca determines whether separation occurs or not; at R larger than 1, the shear difference is considerable, and the Ca effect becomes less dominant.

A computational fluid dynamics model has been developed to examine the separation of an oil film from a spherical oil-coated particle falling through quiescent water due to gravity. Using this model, the separation process was studied as a function of the viscosity ratio of oil to water, R, and the ratio of viscous forces to surface tension, represented by the Capillary number Ca. The governing equations of this flow-induced motion are derived in a non-inertial spherical coordinate system, and discretized using a finite volume approach. The Volume-of-Fluid method is used to capture the oil/water interface. The model predicts two mechanisms for oil separation: at R less than 1, the shear difference between the particle/oil interface and the oil/water interface is not significant and Ca determines whether separation occurs or not; at R larger than 1, the shear difference is considerable, and the Ca effect becomes less dominant.

No description available.

Thesis (Ph.D. (Pharmaceutical Chemistry)--North-West University, Potchefstroom Campus, 2009.

Thesis (Ph.D. (Pharmaceutical Chemistry)--North-West University, Potchefstroom Campus, 2009.

Lorsque des champs électriques sont appliqués à des mélanges eau-huile, les petites gouttelettes d'eau sont attirées entre elles et se regroupent en gouttes plus grosses. Ce processus d’électrocoalescence rend plus efficace la séparation huile-eau par sédimentation.Des données expérimentales sur l’électrocoalescence de très petites gouttelettes sont nécessaires pour améliorer la compréhension de la dynamique de l'interface eau-huile et pour valider les modèles numériques. La configuration simple étudiée dans ce travail de thèse concerne une petite paire de gouttelettes tombant dans une cuve d'huile modèle et soumise à un champ électrique aligné avec l’axe de symétrie des gouttes et la gravité.La première partie du travail a consisté à générer de façon contrôlée d’une paire de très petites gouttelettes (dans la gamme de diamètres 20-200 microns) alignée avec le champ électrique. La génération de goutte à la demande, par méthode éléctrohydrodynamique (EHD) a été améliorée pour un meilleur contrôle du diamètre et de la charge électrique des gouttelettes injectées à partir d'une aiguille métallique unique. Ceci a été obtenu en appliquant à un ménisque d'eau pendant à l’extrémité de l’aiguille des impulsions électriques de forme optimisée.La caractérisation électrique et hydrodynamique des paires de gouttelettes et leur coalescence sont alors principalement déduites de l'analyse des vitesses de chute, avec et sans application d’un champ électrique à courant continu. Des données complètes de positions des gouttelettes et de leur vitesse en fonction du temps sont déduites de prises de vues vidéo. Une attention particulière a été accordée aux visualisations de très petites gouttelettes tombant à petites vitesses, associant des angles multiples de prise de vue, de forts zooms et des vidéos à grande vitesse.La modélisation des différents termes d'interactions hydrodynamiques et électrostatiques entre les gouttelettes permet de déduire des vitesses enregistrées leur masse charge électrique respectives. Quand se produit une coalescence des deux gouttelettes, un enregistrement de la vitesse de la gouttelette résultante, avec et sans tension électrique appliquée, permet de contrôler la conservation de la masse et de la charge électrique, et la validation du procédé.Un premier ensemble de données est constitué d'environ 70 cas différents, avec différentes paire des gouttelettes (dans une plage de diamètre limitée de façon à ce que les vitesses de chute soient comprises entre 0,1 et 0,3 mm/s) et en faisant varier la tension appliquée à courant continu ou alternatif. L'analyse des résultats et des incertitudes expérimentales et un exemple de comparaison possible avec des simulations numériques utilisant le logiciel Comsol Multiphysics ™, permettent d'effectuer des recommandations pour les travaux futurs.Ce travail a été financé par le projet “Fundamental understanding of electrocoalescence in heavy crude oils”; coordonné par SINTEF Energy Research. Le projet a été soutenu par The Research Council of Norway, dans le cadre du contrat n °: 206976 / E30, et par les partenaires industriels suivants: Wärtsilä Oil & Gas Systems AS, Petrobras et Statoil ASA. / When electric fields are applied in oil-water mixtures small water droplets are attracted to others and merge in larger drops. This electrocoalescence process makes more efficient the oil-water separation by sedimentation.Experimental data on the electrocoalescence of very small droplets will be useful to improve the understanding of the dynamics of water-oil interface and to validate numerical models. The simple configuration studied consists in a small droplet pair falling in stagnant model oil, under electric field aligned with the symmetry axis of the droplet pair and the direction of gravity.First part of the work consisted in the well-controlled generation of very small droplet pair (range 20-200 microns) aligned with electric field. Droplet-on-Demand generation by EHD method was improved for a better control of the diameter and electric charge of droplets injected from a single metallic needle. This was obtained by applying to a pendant water meniscus optimized multistage high voltage electric pulses.Electrical and hydrodynamic characterization of the droplet pairs and their coalescence are then mainly deduced from the analysis of falling velocities, with and without applied DC electric field. A complete data set of droplet position and velocity is deduced from video. A special attention was paid to the visualizations of very small droplet and small falling velocities, involving multiple angle of view, strong zooming and high speed video.Modelling the different terms of hydrodynamic and electrostatic interactions between droplets allows deducing from the recorded velocities their respective mass and electric charge. When coalescence occurs, a record of the resulting single droplet velocity, with and without applied voltage, allows controlling the mass and charge conservations and validating the method.A first data set was constituted of about 70 different cases, with varying droplets pair (with a limited diameter range to remain with falling velocities between 0.1 and 0.3 mm/s) and varying applied DC or AC voltage. Analyses of the results and experimental uncertainties, and example of possible comparison with numerical simulations using Comsol Multiphysics™ software, allow performing some recommendations for future work.This work was funded by the project “Fundamental understanding of electrocoalescence in heavy crude oils”; co-ordinated by SINTEF Energy Research. The project was supported by The Research Council of Norway, under the contract no: 206976/E30, and by the following industrial partners: Wärtsilä Oil & Gas Systems AS, Petrobras and Statoil ASA.

Although the interest in vegetable oils as feedstock for biofuel production is not a recent issue, this took great impetus by the need to have alternative energy sources to the use of oil and oil products, with a search for new sources of vegetable oil. The chichá (sterculia striata) is a large tree that measures 8-25 meters high, it is found in the Brazilian Atlantic Forest and it has fast growing, resistance to low temperatures and different altitudes. The seeds are cylindrical and flat with a black fur that comes off as dries. It has up to 42%almond oil, being a potential candidate for obtaining oil in Brazil. In recent years, many researches have been developed in order to make the production of biodiesel, by ethylic route, technically and economically viable. In this point, much has been done with respect to reactional aspects of this process. However, little researches have been done in order to solve problems related to separation and purification steps. Knowing the phase behavior of the systems is vital for the design, operation and control of these units. This study aimed to: 1) study the process of obtaining biodiesel from chichá oil, 2) perform experimental and theoretical study of the liquid-liquid equilibrium (LLE) involving representative substances of the phase equilibrium present in the chichá biodiesel production. It is expected that the experimental results obtained in this study may come to assist the industry of biodiesel production, providing biodiesel production data and phase equilibrium data to these ones. The results showed that the chichá has about 40% oil in its seed, the chichá biodiesel production reached 99% yield in esters using time ration of 0,5 hours, molar ratio oil/alcohol 1/10, 1,5 % oil mass in mass of catalyst and temperature of 30 °C. The data (LLE) for the ternary system chichá biodiesel + ethanol + glycerol and its tie-lines showed a very characteristic behavior, having no significant variation in studied temperatures. / Embora o interesse por óleos vegetais como matéria-prima para produção de bicombustíveis não seja um assunto recente, tomou grande impulso pela necessidade de se dispor de fontes de energia alternativas ao uso do petróleo e derivados, havendo uma busca por novas fontes de óleo vegetal. O chichá (Sterculia striata) é uma árvore de grande porte, de 8 a 25 metros de altura, encontrada na Mata Atlântica brasileira, com crescimento rápido, resistente a baixas temperaturas e diferentes altitudes. As sementes são cilíndricas e achatadas com uma pele preta que se desprende à medida que vai secando. Apresenta, na sua amêndoa até 42% de óleo, sendo uma candidata potencial para a obtenção de óleo no Brasil. Nos últimos anos, muitas pesquisas vêm sendo desenvolvidas visando tornar a produção de biodiesel, via rota etílica, técnica e economicamente viável. Neste sentido, muito têm sido realizado no tocante aos aspectos reacionais deste processo. Entretanto, pouco se tem pesquisado objetivando resolver os problemas relacionados às etapas de separação e purificação. Conhecer o comportamento de fases dos sistemas é vital para o projeto, operação e controle destas unidades. Este trabalho teve como objetivos: 1) estudar o processo de obtenção de biodiesel a partir do óleo de chichá; 2) realizar o estudo experimental e teórico do equilíbrio líquido-líquido (ELL) envolvendo substâncias representativas do equilíbrio de fases presentes na produção de biodiesel do chichá. Espera-se que os resultados experimentais obtidos neste trabalho possam vir a auxiliar o setor de produção de biodiesel, fornecendo a estes, dados de produção do biodiesel e dados do equilíbrio de fases. Os resultados encontrados mostraram que o chichá possui aproximadamente 40% de óleo em sua semente, a produção de biodiesel de chichá alcançou 99 % de rendimento em ésteres utilizando tempo de ração de 0,5 horas, razão molar óleo/álcool 1/10, 1,5% da massa do óleo em massa de catalisador e temperatura de 30 °C. Os dados do (ELL) para o sistema ternário biodiesel de chichá + etanol + glicerina e suas tie-lines mostraram um comportamento muito característico, não tendo variação significativa nas temperaturas estudadas.

The use of oil seeds as a source for biodiesel production constitutes an important raw material, and the encouragement of their production contributes to the agricultural development of the country. In this sense, there was a liquid-liquid equilibrium study of ternary systems: ethyl-glicerina- biodiesel ethanol and methyl-glycerin-methanol biodiesel to 313 K and 323 K. The miscibility limits or bimodal curve for these systems were obtained by the method determining the turbidity point. Data for the construction of mooring lines were determined by preparing mixtures of known concentrations of the three components in the two-phase forming region. These blends, after stirring were maintained at rest until the total separation of the phases, and then it was expected that the equilibrium was reached. After the samples of both phases were collected and analyzed on a balance of drying, where the alcohol was determined percentage of the glycerin rich phase, and the alcohol percentage in rich phase biodiesel. The other two biodiesel components and glycerin were determined using the equation found by the points of the binodal curve raffinate side, which is the phase rich in glycerine, and side extract, which is rich phase biodiesel, and thus created the lines bollard which called tie lines. This study evaluated the behavior of the bimodal curve via ethylic route and methyl at temperatures of 313 K and 323 K, and the study of phase equilibrium for biodiesel system sesame-glycerine-alcohol oil. The results showed that the effect of temperature is not influenced to the solubility of the systems studied, and the curves of the systems were well characterized, and the binodal curves sesame oil biodiesel system + ethanol + glycerin showed similarity to each other, however, there was a variation in the immiscibility region in relation to biodiesel system sesame oil + glycerine + methanol, making it smaller, an increase in the solubility between components. The model used UNIQUAC provided a good representation of experimental data, showing a standard of 1.47% and 0.90% deviations for biodiesel systems sesame oil + glycerine + ethanol and 0.49% and 0.21% for systems biodiesel sesame oil + glycerine + methanol, and there was also slight variation in solubility temperature variation. / Fundação de Amparo a Pesquisa do Estado de Alagoas / O uso de sementes oleaginosas como fonte para produção de biodiesel constitui-se em uma importante matéria prima, e o incentivo da sua produção contribui para o desenvolvimento agrário do país. Nesse sentido, foi realizado um estudo de equilíbrio líquido-líquido dos sistemas ternários: biodiesel etílico-glicerina- etanol e biodiesel metílico-glicerina-metanol a 313 K e 323 K. Os limites de miscibilidade ou curva binodal para estes sistemas foram obtidos pelo método da determinação do ponto de turbidez. Os dados para a construção das linhas de amarração foram determinados pela preparação de misturas de concentrações conhecidas dos três componentes na região de formação de duas fases. Estas misturas, após agitação, foram mantidas em repouso até a total separação das fases, e em seguida, esperou-se que o equilíbrio fosse atingido. Após, as amostras de ambas as fases, foram coletadas e analisadas em uma balança de secagem, onde foi determinado o percentual de álcool presente na fase rica em glicerina, e o percentual de álcool presente na fase rica em biodiesel. Os outros dois componentes biodiesel e glicerina, foram determinados através da equação encontrada pelos pontos da curva binodal do lado rafinado, que é a fase rica em glicerina, e do lado extrato, que é a fase rica em biodiesel, e assim criadas a linhas de amarração as quais chamamos de tie lines. Neste trabalho foi avaliado o comportamento da curva binodal via rota etílica e metílica nas temperaturas de 313 K e 323 K , e o estudo de equilíbrio de fases para o sistema biodiesel do óleo de gergelim-glicerina-álcool. Os resultados obtidos apresentaram que o efeito da temperatura não influenciou para a solubilidade dos sistemas estudados, e que as curvas dos sistemas ficaram bem caracterizadas, sendo que, as curvas binodais do sistema biodiesel do óleo de gergelim + etanol + glicerina apresentou semelhança entre si, porem, houve uma variação na região de imiscibilidade em relação ao sistema biodiesel do óleo de gergelim + metanol + glicerina, tornando-a menor, apresentando um aumento na solubilidade entre os componentes. O modelo utilizado UNIQUAC forneceu uma boa representação dos dados experimentais, apresentando desvios padrão de 1,47% e 0,90% para os sistemas biodiesel do óleo de gergelim + etanol + glicerina e 0,49% e 0,21% para os sistemas biodiesel do óleo de gergelim + metanol + glicerina, assim como também houve pequena variação de solubilidade na variação da temperatura.