Orientador: Eduardo Augusto Caldas Batista / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-23T08:11:39Z (GMT). No. of bitstreams: 1 Basso_RodrigoCorrea_D.pdf: 1825743 bytes, checksum: d974878d6fa879e716be9205980e326d (MD5) Previous issue date: 2013 / Resumo: Uma vez que a decantação é comumente usada na purificação do biodiesel, o conhecimento da distribuição dos componentes entre as duas fases líquidas formadas, dado pelo equilíbrio líquido-líquido (ELL), faz-se necessário. O comportamento deste biocombustível em motores e o dimensionamento de equipamentos para sua produção são dependentes de suas propriedades físicas. As informações referentes ao ELL e as propriedades físicas dos biodieseis etílicos são insuficientes na literatura científica, a despeito de sua importância como combustível completamente biorenovável. Deste modo, os objetivos do presente trabalho foram obter dados experimentais e modelar o ELL de sistemas contendo etanol + biodiesel etilíco + água ou glicerol; simular as etapas de decantação na purificação dos biodieseis; obter dados experimentais e estudar o comportamento da densidade, da viscosidade e do perfil térmico de biodieseis etílicos; desenvolver um modelo para o cálculo da viscosidade de ésteres etílicos e sistematizar uma metodologia preditiva para o cálculo das densidades de biodieseis. Os resultados mostraram que a temperatura teve pouco efeito no ELL de sistemas contendo glicerol + etanol + biodiesel etilíco de óleo de crambe. Os modelos NRTL e UNIQUAC descreveram o ELL dos sistemas com desvios globais menores que 1,22% e 1,07% para os sistemas contendo, respectivamente, água e glicerol. UNIFAC e UNIFAC-Dortmund apresentaram uma inadequada capacidade preditiva, com desvios globais maiores que 1,9% e 2,27% para os sistemas contendo, respectivamente, água e glicerol. A remoção parcial do etanol de sistemas contendo etanol + biodiesel etílico + glicerol reduziu o teor de glicerol na fase rica em biodiesel a concentrações inferiores ao mínimo requerido pelos padrões de qualidade do biodiesel. Usando um decantador para a separação do glicerol e dois conjuntos misturador/separador em contracorrente na lavagem do biodiesel, a quantidade de água requerida para a remoção de etanol e glicerol foi aproximadamente 1/4 da massa do biodiesel a ser purificado, e 1/8 da quantidade de água usada com um único conjunto misturador/separador. Os biodieseis de óleo de crambe e de óleo de coco tiveram, respectivamente, as maiores e as menores viscosidades, e o biodiesel de óleo de macauba teve o maior ponto de fusão entre os biodieseis analisados. A sistematização da metodologia predita para o cálculo de densidade resultou em desvios relativos menores que 0,89% e o modelo desenvolvido para o cálculo da viscosidade de ésteres etílicos resultou em desvios relativos médios menores que 14,73% / Abstract: Since settling is commonly used in the biodiesel purification, the knowledge of the component distribution between both liquid phases, given by the liquid-liquid equilibrium (LLE), is required. The biodiesel behavior in engines and the equipment design for its synthesis process are dependent on physical properties of this biofuel. Despite its importance as a completely renewable biofuel, experimental data in the scientific literature about LLE and physical properties of biodiesel produced by ethanolysis are scarce. Because of this, the aims of the present work were to obtain and to model LLE experimental data of systems containing ethanol + ethyl biodiesel + water or glycerol; to simulate the settling in the biodiesel purification; to determine experimental data and to evaluate the behavior of density, viscosity and thermal profile of ethyl biodiesels; to develop a new model for calculation of ethyl ester viscosity and to present a systematized methodology for biodiesel density calculation. The results showed little temperature effect on the LLE of the systems containing glycerol + ethanol + ethyl biodiesel from crambe oil. NRTL and UNIQUAC models described the LLE of the systems with overall deviations lower than 1.22% and 1.07%, for the systems containing, respectively, water and glycerol. UNIFAC and UNIFAC-Dortmund showed poor predictive capacity, with overall deviations higher than 1.9% and 2.27% for the systems containing, respectively, water and glycerol. Partial removal of ethanol from the systems containing ethanol + ethyl biodiesel + glycerol decreases the glycerol content in the biodiesel-rich phase to lower content than that required by biodiesel standard. Using a settler for glycerol separation and two sets mixer/settler in countercurrent for biodiesel water washing, the water content required for ethanol and glycerol removal was about 1/4 of the mass of biodiesel previous to settling, and 1/8 of the water content required for the biodiesel purification using only a single set mixer/settler. The biodiesels from crambe and coconut oil showed, respectively, the highest and the lowest viscosities, and the biodiesel from macauba pulp oil showed the highest melting point among the studied biodiesels. The systematized methodology resulted in relative deviations lower than 0.89% for the densities, and the developed model for the viscosity calculation showed relative deviations lower than 14.73% / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Orientadores: Martin Aznar, Sérgio Duvoisin Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T20:26:45Z (GMT). No. of bitstreams: 1 Rocha_EnioGomesdeAzevedo_M.pdf: 2064033 bytes, checksum: f91a84bce4c2b9d8bb4142c612dffb37 (MD5) Previous issue date: 2012 / Resumo: O biodiesel é uma fonte de energia renovável promissora e é do interesse das matrizes energéticas brasileiras e mundiais em razão da futura escassez de combustíveis fósseis, e das considerações ambientais sobre a diminuição das emissões poluentes. Este trabalho objetiva a produção de biodiesel etílico a partir de óleo de palma da região amazônica, e a determinação experimental e modelagem termodinâmica de dados de equilíbrio líquido-líquido em sistemas ternários compostos por biodiesel de óleo de palma + etanol + glicerina e biodiesel de óleo de palma + etanol + água, nas temperaturas de 25 °C e 50 ºC, à pressão atmosférica. As técnicas analíticas para determinação das composições das fases incluíram densimetria e índice de refração. Os dados de equilíbrio experimentais foram correlacionados com o modelo NRTL para o coeficiente de atividade e o modelo foi capaz de representar corretamente o comportamento destes dados, fornecendo uma boa descrição dos diagramas de fase dos sistemas estudados / Abstract: Biodiesel is a renewable energy source and is awakening the interest of Brazilian and global energy matrix because of future shortages of fossil fuels and environmental concerns about the reduction of pollutant emissions. This work aims at the production of ethyl biodiesel from palm oil of the Amazon region, and the experimental determination and thermodynamic modeling data of liquid-liquid equilibrium in ternary systems composed by palm oil biodiesel + ethanol + glycerol and palm oil biodiesel + ethanol + water at temperatures of 25 °C and 50 °C, at atmospheric pressure. The analytical techniques for determining the compositions of the phases included densimetry and refractive index. The experimental equilibrium data were correlated with the NRTL model for the activity coefficient. The model was able to correctly represent the behavior of the experimental data, providing a good description of the phase diagrams of the studied systems / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientador: Alex Antonelli / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-21T01:39:17Z (GMT). No. of bitstreams: 1 Garcez_KarlMarxSilva_D.pdf: 2581955 bytes, checksum: 2dfa2df8f3ea59af33216b429c53d794 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho, investigamos os efeitos da pressão sobre as transições entre as fases líquidas e amorfas em silício sobre regime super-resfriado. A investigação é feita através de simulações computacionais, onde técnicas eficientes para cálculo da energia livre, são implementadas sobre o método Monte Carlo. Nossos cálculos, utilizam um potencial interatômico dependente do ambiente local para o Si e confirmam a existência, na região super-resfriada, de uma transição líquido-líquido, entre um líquido de alta densidade e um líquido de baixa densidade. Este líquido de baixa densidade, se mantido sob resfriamento, sofre uma transição vítrea e torna-se um amorfo de baixa densidade. Em pressão nula, a transição líquido-líquido ocorre a cerca de 325 K abaixo da temperatura de fusão encontrada em nossas simulações. Nossos resultados mostram que temperatura de transição líquido- líquido diminui com o aumento da pressão. O aumento da pressão leva a curva de coexistência líquido-líquido à região onde o líquido de baixa densidade torna-se um vidro. De maneira que para pressões acima de 5 GPa, os resultados mostram que a transição líquido-líquido é suprimida pela dinâmica do sistema vítreo. Nós também descobrimos que acima de 5 GPa, a temperatura de transição vítrea é menor do que em pressões mais baixas, sugerindo que sob estas condições a transição vítrea ocorre entre um líquido de alta densidade e um amorfo de alta densidade / Abstract: In this study, we investigated the effects of pressure on the transitions between liquids and amorphous phases of silicon on supercooled regime. Research is done through computer simulations, where efficient techniques for calculating the free energy, are implemented on the Monte Carlo method. Our calculations uses an environment-dependent interatomic potential for Si and confirms, in the supercooled region, the existence of a liquid-liquid transition between a high density liquid and a low density liquid. This low density liquid, if kept under cooling, undergoes a glass transition and becomes a low density amorphous. At zero pressure, the liquid-liquid transition occurs at about 325 K below the melting temperature found in our simulations. Our results show that the liquid- liquid transition temperature decreases with increasing pressure. The increased pressure leads the liquid-liquid coexistence curve to a region where the low-density liquid becomes a glass. So that for pressures above 5 GPa, the results show that the liquid-liquid transition is suppressed by the glassy dynamics of system. We also found that above 5 GPa, the glass transition temperature is lower than at lower pressures, suggesting that under these conditions the glass transition occurs between a high density liquid and a high density amorphous / Doutorado / Física / Doutor em Ciências

Orientador: Rahoma Sadeg Mohamed. / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-01T04:27:33Z (GMT). No. of bitstreams: 1 PessoaFilho_PedrodeAlcantara_D.pdf: 10293388 bytes, checksum: d2122777bc0a4783f681b4c94289e6de (MD5) Previous issue date: 2002 / Resumo: A fonnação de sistemas aquosos bifásicos em conseqüência da adição à água de alguns pares de polímeros, ou de certos polímeros e sais, é um fenômeno bem estabelecido e conhecido. Esses sistemas encontram larga aplicação na separação de moléculas biológicas em laboratório e têm conhecido nos últimos tempos incipiente aplicação industrial; sua correta modelagem tennodinâmica é o objetivo deste trabalho. Inicialmente consideraram-se sistemas formados por dois polímeros. Procurou-se incorporar à equação de Flory-Huggins modificações que levassem em conta a formação de ligações de hidrogênio entre moléculas de água e entre moléculas de água e de polímero, no caso, o poli(etileno glicol). Em uma primeira análise utilizou-se como base do desenvolvimento a teoria quimica, que considera a ligação de hidrogênio uma ligação covalente. Os resultados foram bastante adequados e indicavam que a consideração das ligações cruzadas era suficiente para permitir uma boa modelagem. Assim, outros modelos que levavam em conta a solvatação foram desenvolvidos, em uma primeira abordagem considerando o número de moléculas de água na camada de solvatação constante, depois permitindo que esse valor variasse com a composição. Todos esses modelos tiveram bastante sucesso; entretanto, resultados pouco adequados foram obtidos na utilização da SAFT (teoria estatistica do fluido associativo). A polidispersão da dextrana também foi considerada em alguns cálculos, com sucesso; entretanto, dadas as diferenças existentes entre dados experimentais obtidos em grupos de pesquisa diversos, não foi possivel construir um modelo totalmente preditivo. Estudaram-se também sistemas formados por polímeros e sais. Nesse caso, o esforço teórico foi direcionado à compreensão do papel dos componentes nos tennos devidos à interação eletrostática ¿ por exemplo, polímeros presentes alteram a constante dielétrica e a densidade do meio, devendo portanto alterar a equação de Debye-Hückel, o que, por sua vez, faz com que se prevejam comportamentos irrealistas. Análise acurada revelou que a solução completa do problema demanda a conversão de propriedades obtidas no formalismo de McMillan e Mayer ao formalismo de Lewis e Randall para misturas de solventes ¿ esforço teórico cujo vulto ultrapassa o escopo deste trabalho. Desenvolveu-se também um modelo para sistemas fonnados por polieletrólitos e polímeros neutros. Esse modelo é baseado em uma equação empirica do virial, e considera a ocorrência de várias reações, por meio das quais foi possivel obter um novo modelo de energia de Gibbs excedente que levasse em conta a variação do grau de dissociação iônica em soluções aquosas de polieletrólitos. O modelo fisico de solvatação constante, desenvolvido para sistemas formados por dois polímeros, foi utilizado no estudo da partição de moléculas biológicas. O modelo foi capaz de descrever muito bem resultados de experimentos de partição. Nesse caso, a consideração da polidispersão da dextrana, que afeta muito pouco cálculos de equilíbrio líquido-líquido, modificou de maneira adequada a densidade numérica dessas fases, tomando o modelo mais confiável / Abstract: Aqueous two-phase systems are formed when either two polymers or a polymer and a salt are added to water at certain concentrations. These systems have been widely used to separate biological molecules in laboratory, and have recently found incipient industrial application. This work is aimed at the development of reliable thennodynamic models for these systems. First, systems fonned by two polymers were examined. The Flory-Huggins equation was modified to account for hydrogen bonding occurring between water molecules (self-association) and between water and polymer molecules (solvation). The first modification uses the chemical theory, according to which hydrogen bonding is considered to be equivalent to a covalent bonding. The results obtained were very good and indicated that cross-association alone might bring about this improvement. Purely physical models accounting for solvation were subsequently developed, first by considering the number of water molecules bonded to each polymer molecule as a constant value, and later allowing it to vary with concentration. These models were found very successful. A similar attempt to use the SAFT (statistical associating fluid theory), however, did not provide good results. Polydispersion in polymers such as Dextran was also successfully accounted for, even though it was not possible to establish a completely predictive model due to the discrepancies in experimental data obtained by different research groups. Systems fonned by polymers and salts were dealt with next. In this case, the theoretical investigation was aimed at the understanding of the role of the different compounds in the ca1culation of the tenn that accounts for long range interactions. For instance, polymers modify the dielectric constant and the specific gravity ofthe surrounding medium, thus modifying the Debye-Hückel equation; however, accounting for this effect introduces spurious terms in phase equilibrium ca1culations. A more detailed analysis showed that the correct solution to this problem would require the conversion of properties of mixing ca1culated in the McMillan and Mayer forrnalism to that of Lewis and Randal, a serious and challenging theoretical problem whose solution is beyond the scope of this work. A new thennodynamic model tailored for solutions of polyelectrolytes and neutral polymers was also developed. This model is based on an empirical virial equation and considers the occurrence of some ionic dissociation reactions. Through this picture it was possible to develop a new excess Gibbs energy model accounting for the variation of the ionic dissociation degree in aqueous solutions of polyelectrolytes. The model with constant value for the solvation number, developed for systems fonned by two polymers, was also used to model the partitioning of biological molecules in these systems. The model provided a very good description of partitioning experiments. Accounting for Dextran polidispersion, which has almost no effect on phase equilibrium ca1culations, modifies the numeric density of the liquid phases in equilibrium, and increases the reliability of the model / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

Fresh water in Kuwait is produced by non- conventional methods. About 95% of this water comes from desalinated seawater using multi-stage flash distillation technique and the remainder comes from underground brackish water. The blended water containes organic, inorganic and trace metal impurities within the recommended international standard limits. The purpose of this work is to identify the source of selected trace metals present in the drinking water in Kuwait. Chromium, copper, iron, lead, manganese, nickel, vanadium and zinc have been analysed using atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectroscopy (ICPMS). Efforts were made to improve the preconcentration of the selected metals and their separation from the high concentration of salts in seawater which affect the accuracy and cause major interference in the analysis. Solid-liquid extraction (chelex-100 resin) and liquid-liquid extraction (methyl iso-butyl ketone and freon) with and without back-extraction into nitric acid were investigated. Liquid-liquid extraction without back-extraction proved to give optimum recovery of the selected metals. Results confirmed that both AAS and ICP-MS are suitable for the analysis of trace metals in Kuwait's waters. Although AAS technique proved to be more accurate in analysing the selected metals than ICP-MS, the latter was adopted since its accuracy is acceptable (1.1-4.4%) and it is easier and faster than the former technique. The study revealed that the source of copper, iron, nickel and zinc is the construction materials of the distillation plants, while the source of lead and vanadium is the brackish water. Manganese and chromium concentrations are very low in all sources. No direct relationship between the metal concentration in the seawater and the distillate could be deduced.

Countercurrent chromatography (CCC) is an advanced liquid-liquid extraction technique that purifies chemical components from complex mixtures. The Brunel CCC' is a J-type centrifuge based upon this technique. This machine can process 5g quantities of sample every 5 hours [Sutherland 1998]. To process 1 tonne of sample per year would require 200 Brunel CCCs, which is not practical as an industrial process. A practical alternative is to use one machine with 200 times the processing capability. To construct such a machine requires a greater understanding of the stationary phase retention inside a coil (column) and the column efficiency (mass transfer between the mobile and stationary phases). This thesis contains research into stationary phase retention. A hypothesis that all J-type centrifuges act as constant pressure drop pumps is proposed. This hypothesis combined with the Hagan-Poiseuille equation for laminar flow produces a theoretical basis for plotting the stationary phase retention against the square root of the mobile phase flow rate as proposed by Du et al [1999]. Supporting experimental evidence is presented showing that the mobile phase flows in a laminar manner and that the pressure drop across a coil is constant for a given set of operating conditions. It is shown that the pressure drop is the same in both normal and reverse phase modes if specific conditions are met. The pressure drop is shown to be independent of tubing bore for helical coils provided that the same helical pitch is used. The experimental results also show how the pressure drop varies with the phase system and rotational speed. Hopefully this is a significant advance in predicting the stationary phase retention of industrial scale J-type centrifuges.

Cette thèse avait pour objectif de développer de nouveaux systèmes d’extraction liquide-liquide compatibles avec le procédé Prayon pour la purification de l’acide phosphorique produit par voie humide. Une étude bibliographique complète des solvants d’extraction étudiés dans la littérature pour l’extraction liquide-liquide de l’acide phosphorique nous a permis d’identifier des candidats potentiellement intéressants. Une étude approfondie des propriétés d’extraction de ces systèmes et de leur sélectivité vis-à-vis des espèces métalliques nous a finalement permis de nous focaliser par la suite sur trois solvants d’extraction : le dibutyl éther (DBE), le diisobutyl carbinol (DiBC) dilué dans le diisopropyl éther (DiPE) et la Fentamine T0810 (ATS) dilué dans le DiPE. La formulation de ces mélanges a ensuite été optimisée en veillant à étudier le comportement de ces systèmes à chaque étape du procédé d’extraction liquide-liquide, c’est à dire l’extraction, la désextraction et le lavage. Cette étude a également permis de fixer les conditions opératoires optimales, notamment le rapport des volumes des phases. Au cours de cette étude, des phénomènes complexes de transitions de phases réversibles de la phase organique de monophasique vers biphasique (formation de troisième phase) et biphasique vers monophasique (retour à une phase organique unique) ont été mis en évidences expérimentalement. Pour finir, un modèle physicochimique d’extraction fondé sur des bilans de masse a été développé. Ce modèle s’avère très utile pour décrire l’extraction de l’acide phosphorique et de l’eau et la variation des volumes des phases au cours de l’extraction. / This PhD thesis was focused on the development of new extraction systems to purify phosphoric acid from wet phosphoric acid (WPA). The new system should be respectful of the current Prayon’s process flowsheet designed for the use of the mixture tri-n-butyl phosphate(TBP) and diisopropyl ether (DiPE) as extraction solvent. Firstly, extractants exhibiting different structures and functional groups were screened in order to assess their efficiency and selectivity towards phosphoric acid. Three new promising extraction systems were identified: diisobutyl ether (DBE), diisocarbinol (DiBC) in DiPE, and Fentamine T0810 (ATS) in DiPE. Secondly, our effort was directed to the comprehension of the physico-chemical phenomena involved in the extraction of phosphoric acid by the mixture TBP/DiPE at first, and enriched to describe the other systems studied later. Finally, a simulation model describing the solvent extraction of phosphoric acid by the solvent currently employed by Prayon is presented. This model accounts for the significant volume variation during the extraction of phosphoric acid and allows performing optimizations of extraction parameters even at very high phosphoric acid concentrations (6-14M).

La chimie séparative est un pilier du développement technologique en matière d’extraction, de séparation ou de remédiation sélective de molécules ou de métaux. Elle trouve des applications dans les domaines de l’électronique, des énergies renouvelables, de la médecine ou de la chimie, qui nécessitent plus que jamais l’utilisation de « métaux stratégiques ». L’extraction liquide-liquide est une technique de séparation qui intervient dans les procédés hydrométallurgiques pour la récupération de métaux stratégiques issus de gisements primaires, secondaires et de mines urbaines.Ce travail s’inscrit donc dans une vision globale d’optimisation des procédés d’extraction liquide-liquide appliqués en synergie, par une démarche de compréhension des mécanismes à l’origine de la synergie, et de généralisation de ces mécanismes mis à jour à l’ensemble des systèmes d’extraction synergiques. Cette compréhension des mécanismes devant ainsi permettre de prédire et de concevoir de nouveaux mélanges d’extractants synergiques.Pour mieux comprendre les moteurs à l’origine des phénomènes synergiques, une méthodologie adaptée pour la caractérisation des structures supramoléculaires des systèmes extractants en phase organique a été exploitée pour ces travaux de thèse. L’utilisation des techniques de Diffusion de Rayons-X/Neutrons aux Petits Angles (DXPA/DNPA) et de tensiométrie interfaciale ont été déterminantes pour la compréhension des mécanismes sous-jacents à la synergie. L’approche thermodynamique de l’extraction liquide-liquide qui présente l’intérêt d’estimer quantitativement les moteurs essentiels mis en jeu dans les mécanismes d’extraction liquide-liquide, apparait ainsi comme un outil essentiel pour la compréhension des systèmes synergiques. L’application de ces clés de compréhension a permis de concevoir un nouveau système synergique pour l’extraction des terres rares en milieu phosphorique. / Separative chemistry is a pillar of technologic development in extraction, separation and selective remediation of metals and molecules. It finds its applications in the fields of electronic, renewable energy, medicine and chemistry, which require more than ever the use of “Strategic Metals”. The liquid-liquid extraction is a separation technique that is involved in hydrometallurgical processes for the recovery of strategic metals from primary deposits, secondary and urban mines.This work is part of global vision of optimization of liquid-liquid extraction processes used in synergy, consisting in understanding the mechanisms underlying the synergy, and generalizing these mechanisms to all synergistic extraction systems. The understanding of these mechanisms underlying synergism aims at predicting and developing new synergistic extractants mixtures.To better understand the driving forces at the origin of synergistic phenomena, a suitable methodology for the characterization of supramolecular structures of extractant in the organic phase was exploited during this thesis work. The use of techniques like Small Angle Neutron / X-ray Scattering X-ray (SAXS /SANS) and interfacial tensiometry was crucial for the understanding of the synergistic mechanisms. A thermodynamical was also proposed to estimate quantitatively the key driving forces involved in the liquid-liquid extraction mechanisms. The application of these keys of comprehension helped to design a new synergistic system for the extraction of rare earths elements from phosphoric medium.

I advanced the understanding of particle morphology and its implications for the behavior and effects of atmospheric aerosol particles. I have developed new experimental methods for the Aerosol Optical Tweezers (AOT) system and expanded the AOT’s application into studying realistic secondary organic aerosol (SOA) particle phases. The AOT is a highly accurate system developed to study individual particles in real-time for prolonged periods of time. While previous AOT studies have focused on binary or ternary chemical systems, I have investigated complex SOA, and how they interact with other chemical phases, and the surrounding gas-phase. This work has led to new insights into liquid-liquid phase separation and the resulting particle morphology, the surface tension, solubility, and volatility of SOA, and diffusion coefficients of SOA phases. I designed a new aerosol optical tweezers chamber for delivering a uniformly mixed aerosol flow to the trapped droplet’s position. I used this chamber to determine the phase-separation morphology and resulting properties of complex mixed droplets. A series of experiments using simple compounds are presented to establish my ability to use the cavity enhanced Raman spectra to distinguish between homogenous single-phase, and phase-separated core-shell or partially-engulfed morphologies. I have developed a new algorithm for the analysis of whispering gallery modes (WGMs) present in the cavity enhanced Raman spectra retrieved from droplets trapped in the AOT. My algorithm improves the computational scaling when analyzing core-shell droplets (i.e. phase-separated or biphasic droplets) in the AOT, making it computationally practical to analyze spectra collected over many hours at a few Hz. I then demonstrate for the first time the capture and analysis of SOA on a droplet suspended in an AOT. I examined three initial chemical systems of aqueous NaCl, aqueous glycerol, and squalane at ~ 75% relative humidity. For each system I added α-pinene SOA – generated directly in the AOT chamber – to the trapped droplet. The resulting morphology was always observed to be a core of the initial droplet surrounded by a shell of the added SOA. By combining my AOT observations of particle morphology with results from SOA smog chamber experiments, I conclude that the α-pinene SOA shell creates no major diffusion limitations for water, glycerol, and squalane under humid conditions. My AOT experiments highlight the prominence of phase-separated core-shell morphologies for secondary organic aerosols interacting with a range of other chemical phases. The unique analytical capabilities of the aerosol optical tweezers provide a new approach for advancing the understanding of the chemical and physical evolution of complex atmospheric particulate matter, and the important environmental impacts of aerosols on atmospheric chemistry, air quality, human health, and climate change.

The fuel industry in many parts of the world is blending alcohols with motor fuel either to extend the fuel or to improve its octane rating or both. Unfortunately alcohols are hygroscopic and as a result, water becomes a component of the fuel. This can lead to phase separation and the formation of a water-rich layer which could have serious corrosion consequences. In an attempt to understand the phase-splitting in alcohol-petrol-water blends, phase equilibria in ternary systems (alcohol-hydrocarbon-water) have been determined by experiment. The phase equilibria in these ternary systems are also discussed in terms of modern theories of liquid mixtures and the UNIQUAC theory is applied to the "ethanol + benzene + water" ternary system. The alcohols are all the C₁, C₂, C₃ and C₄ alcohols, and the hydrocarbons include those typically found in petrol, e.g. cyclohexane, benzene and substituted benzenes.