Les effluents pétroliers contiennent généralement des hydrocarbures lourds en faible quantité. Toutefois dans certains gisements, où les fluides sont stockés à des profondeurs importantes dans des conditions de pression et de température proches des conditions critiques, la proportion de composés lourds peut être significative et donc engendrer des modifications importantes des propriétés thermophysiques de ces fluides, particulièrement sur les équilibres de phases liquide - solide. En effet, suivant la proportion et la nature de la fraction lourde, la température de fusion peut s'élever de façon drastique. Ainsi la présence de composés lourds peut provoquer l'apparition de dépôts solides au sein des équipements d'exploitation ou dans les conduits de transport. La prévention de ces dépôts solides, qui constituent un risque important de détérioration du matériel, passe, en premier lieu, par la détermination précise des conditions d’apparition des premiers cristaux de paraffine au sein des fluides de gisement. Dans cette perspective, cette thèse a pour objectif principal le développement d’une méthode expérimentale d’observation des conditions de formation des cires au sein des huiles brutes ainsi que de leur évolution en fonction des conditions de température et de pression. Pour cela, une technique microscopique couplée à une analyse d’image novatrice est proposée. / Most of petroleum reservoir fluids contain a small amount of heavy hydrocarbons. However, in some deep oil reservoirs, in which fluids are stored under high pressure and high temperature conditions, the light components in supercritical state are able to dissolve a significant amount of high molecular weight components. The heavy components, which are soluble in crude oil under reservoir conditions, may precipitate as a waxy solid phase when temperature decreases below the cloud point. According to the nature and the quantity of heavy components, the wax appearance temperature may be high in some crude oils (higher than the water freezing point). In this case, due to a decrease in temperature or due to a modification of the composition of light components, wax deposition may occur during production or when oil is transported through pipelines across cold areas. Thus, the presence of heavy components in reservoir fluids constitutes a potential risk of plugging process equipment at different stages of exploitation. To prevent and to avoid paraffin deposition in pipelines, it is first required to determine the wax appearance conditions throughout the pressures encountered during production.To this end, the main objective of this thesis is the design and the development of a new experimental technique for determining visually the liquid-solid phase transitions in crude oils. This technique rests on a digital microscopic image analysis to detect the onset of wax precipitation and the evolution of waxy solid as a function of temperature and pressure.

In the sol gel production of high surface area catalyst, the template, a surfactant, is the key component of the process. A template too soluble in the supercritical dryingextraction process can yield a catalyst with a lower surface area. A template completely insoluble in the supercritical drying-extraction process can lead to a longer calcinations step and lower catalyst surface area. Template recovery also enhances the economic feasibility of plant scale production of high surface area catalyst. For these reasons knowing surfactant solubility in supercritical media is important. The solubility of surfactants tert-octylphenoxypolyethoxyethanol (commercially available and hereafter referred to as Triton X-114) and alkyloxypolyethyleneoxyethanol (commercially available and hereafter referred to as Tergitol 15-S-9) in supercritical carbon dioxide and ethanol entrainer have been determined at five-degree increments from 35 oC to 50oC. The solubility of the surfactants was determined by charging a variable volume cloud point system with the entrainer-surfactant mixture followed by liquid carbon dioxide. With the resulting stirred homogeneous mixture heated to temperature, cloud point pressures were observed as the phase analyzer cell was pressurized by adjusting the variable volume. An average of five values for cloud point pressure is reported here. The mixture behaviors were modeled using the Improved Rackett equation and the Peng-Robinson-Stryjek-Vera (PRSV) equation of state with Wong-Sandler (WS) mixing rules. For the Carbon Dioxide (CO 2) (1) – Ethanol/Triton X-114 (2) mixtures studied, compositions ranged from 93.2 mol% CO 2 to 97.7 mol% CO2. The solubility of Triton X-114 ranged from 0.02 mol% to 0.05 mol% at temperatures ranging from 35 oC to 50oC. Cloud point pressures observed for this system range from 95 bar to 143 bar. For the CO 2 (1) – Ethanol/Tergitol 15-S-9 (2) mixtures studied, compositions ranged from 92.3 mol% CO 2 to 94.4 mol % CO2. The solubility of Tergitol 15-S-9 ranged from 0.02 mol% to 0.03mol% at temperatures ranging from 35 oC to 50oC. Cloud point pressures observed for this system range from 89 to 154 bar.

Orientador: Marco Aurelio Zezzi Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T22:51:49Z (GMT). No. of bitstreams: 1 Lopes_AlineSoriano_M.pdf: 3574562 bytes, checksum: 6e7d02685ed814950db0ef3f76b933c4 (MD5) Previous issue date: 2005 / Mestrado / Quimica Analitica / Mestre em Química

Orientador: Marco Aurelio Zezzi Arruda / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T21:48:44Z (GMT). No. of bitstreams: 1 Coelho_LucianaMelo_D.pdf: 3258414 bytes, checksum: bf5794c1897da59a91597510c34ed02a (MD5) Previous issue date: 2005 / Doutorado / Quimica Analitica / Doutor em Quimica

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O presente trabalho enfoca o desenvolvimento de procedimentos analíticos limpos através da extração e pré-concentração de íons metálicos em ponto nuvem para aumento de sensibilidade, melhoria de seletividade e substituição de solventes tóxicos. Cobre(II), ferro(II) e níquel(II) foram extraídos simultaneamente em digeridos de materiais vegetais, utilizando como agente extrator o Triton X-114, após formarem complexos hidrofóbicos com o 1,2-tiazolilazo-2-naftol (TAN). Os analitos foram determinados por espectrometria de absorção atômica com chama (Cu, Fe e Ni) ou por espectrofotometria de absorção molecular (Fe). A determinação de Cu e Ni por espectrofotometria de absorção molecular foi inviabilizada por interferências espectrais causadas pela formação de complexos com diversos íons metálicos encontrados nos digeridos dos materiais vegetais. Nas medidas por FAAS, os limites de detecção (99,7 % de confiança) foram estimados em 1,10 e 5 µg L-1 para cobre, ferro e níquel, respectivamente. Respostas lineares foram observadas para cobre e ferro na faixa de concentração de 25-200 µg L-1 e para o níquel entre 5 e 80 µg L-1 . O fator de enriquecimento foi estimado em 30 e a extração dos analitos foi quantitativa, de acordo com medidas efetuadas no sobrenadante após extração. Na determinação de ferro por espectrofotometria de absorção molecular, o limite de detecção foi estimado em 1 µg L-1 , com resposta linear entre 6 e 60 µg L-1 e fator de enriquecimento estimado em 20. Após digestão com ácidos diluídos em forno de microondas, o procedimento proposto foi aplicado à determinação dos analitos em digeridos de materiais de referência certificados, sendo os resultados concordantes com os valores certificados a nível de confiança de 95 %. O consumo de reagentes foi estimado em 50 mg Triton X-114 e 150 µg TAN por determinação. / This work is focused on the development of green analytical procedures for cloud-point extraction and concentration of metal ions, aiming increasing sensitivity, improving selectivity and avoiding the use of toxic solvents. Copper(II), iron(II) and nickel(II) were simultaneously extracted from plant materials digests, by using Triton X-114 as extracting agent, after formation of hydrophobic complexes with 1,2- tiazolylazo-2-naphthol (TAN). The analytes were determined by flame atomic absorption spectrometry (Cu, Fe and Ni) or by molecular absorption spectrophotometry (Fe). The determination of Cu and Ni by UV-vis spectrophotometry was hindered by spectral interferences caused by the formation of complexes with several metal ions in the sample digests. In the measurements by FAAS, the detection limits (99.7 % confidence level) were estimated as 1, 10 and 5 µg L-1 for copper, iron and nickel, respectively. Linear responses were observed in the 25-200 µg L-1 range for copper and iron and 5-80 µg L-1 for nickel. The enrichment factor was estimated as 30 and the extraction was quantitative, as evaluated by measurements in the supernatant solution after extraction. For iron determination by UV-vis spectrophotometry, the detection limit was estimated as 1 µg L-1 , with linear response within 6 and 60 µg L-1 and enrichment factor of 20. After digestion with diluted acids in microwave oven, the procedure was applied to the determination of the metals in reference materials and the results agreed with the certified values at the 95 % confidence level. The reagent consumption was estimated as 50 mg Triton X-114 and 150 µg TAN per determination.

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Orientador: Marco Aurelio Zezzi Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T13:14:37Z (GMT). No. of bitstreams: 1 Silva_MarceloAnselmoOseasda_M.pdf: 1369513 bytes, checksum: 35e33836144e52420b1164f512aa97e9 (MD5) Previous issue date: 2008 / Resumo: Nesta dissertação foi estudado o comportamento de partição da albumina, proteína presente em elevada concentração no plasma sangüíneo e que interfere na determinação em diversas técnicas analíticas. No estudo efetuado foram avaliados diferentes sistemas aquosos de duas fases, explorando um fenômeno denominado ponto nuvem. Tais sistemas empregam surfactantes, sob condições experimentais específicas, obtendo-se a formação de duas fases imiscíveis: uma rica e outra pobre em tensoativo. Observou-se que devido às características hidrofílicas da albumina, bem como à dimensão dos agregados formados, sua extração para fase rica em tensoativo apresenta valores de coeficiente de partição que não ultrapassam 0,66 o que representa uma eficiência de extração de ca.40%. A extração da proteína apresentou-se viável mediante a utilização de uma mistura composta por um tensoativo não-iônico (Triton® X-114), que possibilita a separação de fases em temperatura biocompatível, na presença de outro tensoativo iônico (dodecil sulfato de sódio - SDS), que atua favorecendo as interações eletrostáticas entre os agregados e as moléculas protéicas, desde que se trabalhe em meio com pH abaixo de 5,0. Análises de dicroísmo circular complementaram o estudo e fornecerem evidências de que a aplicação do sistema baseado na mistura composta por Triton® X-114 e SDS causava desnaturação parcial da proteína, o que não inviabilizou sua aplicação para extração da mesma em uma amostra real. A eficiência deste sistema foi, então, avaliada para a remoção de albumina em plasma sangüíneo. Um coeficiente de partição de 1,1 foi obtido, indicando que ca.51% das proteínas encontravam-se na fase rica em tensoativo. As amostras submetidas ao procedimento de extração também foram avaliadas frente à técnica de eletroforese em gel, sendo que a fase pobre em sufactante apresentou um perfil eletroforético mais detalhado quando comparada a uma amostra que não foi submetida ao procedimento proposto. Já na fase rica em surfactante, foi observada a presença majoritária de albumina e, em menor concentração, outras proteínas de grande abundância no plasma tais como imunoglobulina G e transferrina. Por fim, o método apresentou desempenho semelhante ao de sistemas disponíveis comercialmente para remoção de albumina, tal como o sistema da Millipore®, apresentado neste trabalho / Abstract: In this work the partition behavior of albumin was studied, which is found at high concentrations in blood plasma, which interferes in many analytical techniques determinations. The present study evaluated different aqueous two-phase systems, exploiting a phenomenon called of cloud point. These systems employ surfactants under specific experimental conditions, enabling formation of two immiscible phases: one rich and another poor in surfactant. Due to the hydrophilic characteristcs of albumin, as well as its aggregate dimensions, its extration to the surfactant rich phase presented partition coefficients lower than 0.66, representing and extraction efficiency of ca. 40%. Protein extraction was feasible by applying a mixture comprised of a nonionic surfactant (Triton® X-114), which allowed the phase separation at biocompatible temperatures, and an ionic one (sodium dodecylsufate - SDS), wich promotes eletrostatic interactions between aggregates and protein molecules, since the extraction procedure is carried out at pH 5.0. Circular dichroism analysis complemented the study and it showed that a system based on a Triton® X-114 and SDS mixture causes partial protein denaturation, but its application for a real sample is feasible. The efficiency of this was evaluated for albumin removal from blood plasma. A partition coefficient of 1.1 was obtained, indicating that ca. 51% of proteins were contained in the surfactant rich phase. Albumin depleted samples were submitted to gel eletrophoresis and the surfactant poor phase presented a more detailed gel electrophoresis profile, when compared with a crude sample. The surfactant rich phase reveled that albumin is the predominant protein present, but it is possible to find other highly concentrated plasmatic proteins including immunoglobulin G and transferrin. Finally, the method presented similar performance when compared with commercially available systems for albumin removal, such as the Millipore® system, wich was also evaluated in this work / Mestrado / Quimica Analitica / Mestre em Química

Orientador: Edvaldo Sabadini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T13:40:57Z (GMT). No. of bitstreams: 1 Sant'AnnaJunior_Walcyr_M.pdf: 635340 bytes, checksum: 1249edac738f7933eee08fdecb6d0d7f (MD5) Previous issue date: 2001 / Resumo: Este trabalho envolve o estudo do equilíbrio de fase líquido-líquido apresentado pelo sistema poli(etileno glicol), (PEG) e hidrocarbonetos aromáticos (HA). Os diagramas de fase são do tipo UCST (upper critical solution temperature), sendo que o grau de miscibilidade é fortemente dependente da massa molar do PEG e do número de CH2 presentes na cadeia alifática das moléculas dos HA. Também são mostrados estudos realizados com os isômeros o, m, e p-xileno e n e iso-propil benzeno, permitindo, nestes casos, verificar a influência da posição do substituinte e da estrutura da cadeia alifática na miscibilidade deste sistema. Os diagramas foram obtidos a partir de medidas visuais de turbidez (ponto de névoa) para as diferentes soluções poliméricas. Neste trabalho procuramos discutir os aspectos entálpicos e entrópicos que levam à separação de fases. O modelo de Flory-Huggins para soluções poliméricas foi utilizado para determinar os parâmetros de interação PEG- HA / Abstract: This work is concerned with the liquid-liquid phase equilibrium shown by a system composed of poly(ethylene glycol) [PEG] and aromatic hydrocarbons [AH]. The diagrams were obtained by cloud point titration. Studies were carried out using o, m, p-xylene isomers and normal and iso-propyl benzene isomers, in order to verify the influence of the substituent position and of the aliphatic chain structure on the miscibility of the system. The phase diagrams obtained are of the UCST (upper critical solution temperature) class. The miscibility is strongly dependent on PEG molar weight and on the number of CH2 units of the aliphatic chain. The Flory-Huggins model for polymeric solutions was employed to determine the PEG-AH interaction parameters. The enthalpic and entropic contribution which lead to phase separation are discussed / Mestrado / Físico-Química / Mestre em Química