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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Application of the HLD and NAC Models to the Formation and Stability of Emulsions

Kiran, Sumit K. 10 January 2014 (has links)
This thesis explored how asphaltene and naphthenic amphiphile species influence the formation (morphology and size) and stability of heavy crude oil (bitumen) emulsions. It was experimentally shown that asphaltenes produce water-in-oil emulsions. Naphthenic amphiphiles on the other hand flip the emulsion morphology to oil-in-water. It was further demonstrated that the size and stability of these emulsions is influenced by physicochemical effects such as the pH, solvent-bitumen-water ratios, solvent aromaticity, and temperature. In view of these findings, the hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC) models were looked at as potential means for predicting the formation and stability of emulsions. Owing to the complexity of bitumen emulsions, however, the HLD and NAC models were instead tested against well-defined sodium dihexyl sulfosuccinate-toluene-water emulsions. The morphologies of these emulsions were predicted as a function of the formulation salinity whereas corresponding droplet sizes were predicted as a function of the continuous phase density and interfacial tension (γow). Emulsion stability trends were in turn predicted using a collision-coalescence-separation assumption. From this assumption, emulsion stability was expressed as a function of the emulsion droplet collision frequency and activation energy. The key parameters of the highly scrutinized activation energy term included the γow, interfacial rigidity, and critical film thickness. In applying the same modeling approach to the stability of other emulsions already published in the literature, it was found that the rigidity of adsorbed multilayer/liquid crystal films cannot yet be fully accounted for. This shortcoming was the reason for which only minimum stability times were reported for bitumen emulsions.
72

Application of the HLD and NAC Models to the Formation and Stability of Emulsions

Kiran, Sumit K. 10 January 2014 (has links)
This thesis explored how asphaltene and naphthenic amphiphile species influence the formation (morphology and size) and stability of heavy crude oil (bitumen) emulsions. It was experimentally shown that asphaltenes produce water-in-oil emulsions. Naphthenic amphiphiles on the other hand flip the emulsion morphology to oil-in-water. It was further demonstrated that the size and stability of these emulsions is influenced by physicochemical effects such as the pH, solvent-bitumen-water ratios, solvent aromaticity, and temperature. In view of these findings, the hydrophilic-lipophilic deviation (HLD) and net-average curvature (NAC) models were looked at as potential means for predicting the formation and stability of emulsions. Owing to the complexity of bitumen emulsions, however, the HLD and NAC models were instead tested against well-defined sodium dihexyl sulfosuccinate-toluene-water emulsions. The morphologies of these emulsions were predicted as a function of the formulation salinity whereas corresponding droplet sizes were predicted as a function of the continuous phase density and interfacial tension (γow). Emulsion stability trends were in turn predicted using a collision-coalescence-separation assumption. From this assumption, emulsion stability was expressed as a function of the emulsion droplet collision frequency and activation energy. The key parameters of the highly scrutinized activation energy term included the γow, interfacial rigidity, and critical film thickness. In applying the same modeling approach to the stability of other emulsions already published in the literature, it was found that the rigidity of adsorbed multilayer/liquid crystal films cannot yet be fully accounted for. This shortcoming was the reason for which only minimum stability times were reported for bitumen emulsions.
73

Craqueamento de hidrocarbonetos naftênicos sobre zeólitas HZSM-12 modificadas – rendimento e seletividade a olefinas leves

Silva Júnior, José Roberto da 30 September 2015 (has links)
Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2016-10-21T11:11:40Z No. of bitstreams: 1 TeseJRSJ.pdf: 5314232 bytes, checksum: 9352e78958e9a2f45a12e9a77f564bdd (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:37:37Z (GMT) No. of bitstreams: 1 TeseJRSJ.pdf: 5314232 bytes, checksum: 9352e78958e9a2f45a12e9a77f564bdd (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:37:44Z (GMT) No. of bitstreams: 1 TeseJRSJ.pdf: 5314232 bytes, checksum: 9352e78958e9a2f45a12e9a77f564bdd (MD5) / Made available in DSpace on 2016-11-08T18:37:52Z (GMT). No. of bitstreams: 1 TeseJRSJ.pdf: 5314232 bytes, checksum: 9352e78958e9a2f45a12e9a77f564bdd (MD5) Previous issue date: 2015-09-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / It was studied the catalytic performance of ZSM-12 zeolites modified by desilication in the cracking of naphthenic hydrocarbons. ZSM-12 zeolites with nominal a SiO2/Al2O3 ratio were synthesized during 96 or 144 h under hydrothermal conditions and the obtained zeolites were treated with NaOH solutions under different conditions. The samples were characterized by thermogravimetric analysis (TA), X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, temperature programmed desorption of ammonia (NH3-TPD), 27Al MAS NMR spectroscopy, energy-dispersive X-ray spectroscopy (EDX) and infrared spectroscopy (Py-FTIR). The treatment with NaOH solutions under mild conditions was more effective for the ZSM-12 zeolite synthesized during 96 h. For the HZ12-96-0,2 sample, obtained by treatment at 35 °C with 0.2 mol.L-1 NaOH solution during 15 min, it was verified an increase in the external surface area and the formation of mesopores in the range of 2 to 14 nm. On that zeolite occurred a higher yields to light olefins during the cracking of cyclohexane at 400 °C and also in the cracking of methyl and ethylcyclohexane at 450 °C. This result was mainly related to the higher density of acid sites exhibited by the HZ12-96-0,2 zeolite compared with the parent ZSM-12 one, as consequence of the applied alkaline treatment. It was also verified that the ZSM-12 zeolites modified by more severe alkaline treatment (0.5 or 1.0 mol.L-1 NaOH solution at 80 °C for 30 min) presented significant increase of the external surface area and mesopores volume. The catalytic cracking of cyclohexane, methylcyclohexane and ethylcyclohexane at 500 °C, as well as the physicochemical characteristics of the MZ12-96-0,5 zeolite enhanced the formation of light olefins. The highest yield to light olefins was obtained on that zeolite during the cracking of ethylcyclohexane, which increased 9% when compared with the yield obtained on the not modified HZSM-12 zeolite. The selectivity to light olefins on the studied HZSM-12 zeolites was strongly influenced by presence of a side chain in the naphthenic ring (methyl or ethyl), as well as by the employed cracking operating conditions. / Estudou-se o desempenho de zeólitas ZSM-12 modificadas por dessilicalização no craqueamento de hidrocarbonetos naftênicos. Zeólitas ZSM-12 com razão SiO2/Al2O3 igual a 80 foram sintetizadas em 96 ou 144 h sob condições hidrotérmicas. As zeólitas ZSM-12 obtidas foram modificadas sob diferentes condições de tratamento alcalino com soluções de NaOH e posteriormente caracterizadas por termogravimetria, difratometria de raios X, microscopia eletrônica de varredura, fisissorção de nitrogênio, dessorção de amônia à temperatura programada, ressonância magnética nuclear do 27Al, espectroscopia de energia dispersiva de raios X e espectroscopia na região do infravermelho com adsorção de piridina. O tratamento alcalino, sob condições mais brandas, foi mais efetivo para a zeólita ZSM-12 sintetizada em menor tempo de cristalização (96 h). Para a zeólita HZ12-96-0,2, obtida por tratamento com solução de NaOH 0,2 mol.L-1 a 35 °C por 15 min, verificou-se um aumento na área superficial externa e distribuição de tamanho de mesoporos entre 2 e 14 nm. Nessa zeólita, ocorreu um maior rendimento a olefinas leves no craqueamento de cicloexano a 400 °C e, também, no craqueamento de metil- e etil-cicloexano realizado a 450 °C. Esse resultado foi relacionado, principalmente, com a maior concentração de sítios ácidos na zeólita HZ12- 96-0,2, em relação à zeólita HZSM-12 precursora, como consequência do tratamento alcalino. Verificou-se, também, que as zeólitas ZSM-12 modificadas por tratamento alcalino, sob condições mais severas (solução de NaOH 0,5 ou 1,0 mol.L-1 a 80 °C por 30 min), apresentaram aumento significativo de área superficial externa e volume de mesoporos. O craqueamento de cicloexano, metil- e etil-cicloexano realizado a 500 °C, assim como as características físicas e químicas da zeólita MZ12-96-0,5, favoreceram a formação de olefinas leves. O maior rendimento a olefinas leves ocorreu durante o craqueamento do etil-cicloexano sobre essa zeólita, com aumento desse rendimento em torno de 9% quando comparado ao rendimento obtido sobre a zeólita HZSM-12 não modificada. A seletividade a olefinas leves sobre as zeólitas HZSM-12 preparadas neste estudo sofreu forte influência da presença da cadeia lateral no anel naftênico (metil ou etil), assim como também das condições operacionais de craqueamento empregadas.
74

Estudos de AvaliaÃÃo e Melhoramento de Produtos para IndÃstria de PetrÃleo e de Bioderivados / Studies of Evaluation and Improvement of Petroleum-based and Bio-based Products

Francisco Murilo Tavares de Luna 23 January 2012 (has links)
Neste trabalho foram realizados estudos para avaliaÃÃo e modificaÃÃo de derivados de petrÃleo e de bioderivados. Na primeira parte deste estudo foi avaliada a seletividade de adsorÃÃo de C8 aromÃticos em peneiras moleculares comerciais. A separaÃÃo dos isÃmeros de xilenos à um importante processo na indÃstria petroquÃmica. As tÃcnicas de cromatografia em headspace e pulsos cromatogrÃficos foram utilizadas para obtenÃÃo de dados experimentais de equilÃbrio de adsorÃÃo. Esta abordagem pode ser muito Ãtil para a seleÃÃo de adsorventes, bem como para investigar a variaÃÃo na seletividade em relaÃÃo à composiÃÃo e temperatura do processo. As seletividades de adsorÃÃo de misturas multicomponentes determinadas atravÃs do mÃtodo de pulsos cromatogrÃficos confirmaram os valores obtidos utilizando os experimentos de cromatografia em headspace. Os valores indicaram o carÃter de para-seletividade dos zeolitos Y (αpx/ox ~ 4) e beta (αpx/ox ~ 2) e de orto-seletividade para os zeolitos mordenita (αox/px ~ 1,5). Na segunda parte deste trabalho foi estudado o processo de adsorÃÃo de poliaromÃticos com misturas modelo e com amostras de Ãleos naftÃnicos pesados (ONP). Os experimentos com as misturas modelo serviram para estudar a capacidade de adsorÃÃo de poliaromÃticos dos materiais, avaliar os parÃmetros de processo e selecionar os materiais mais promissores (Norit 830W e Norit 1240 plus) para avaliaÃÃo com amostras de ONP. As amostras de ONP foram caracterizadas e apresentaram altos teores de poliaromÃticos (8,2% m/m). AtravÃs dos experimentos em coluna, foi possÃvel avaliar a capacidade de adsorÃÃo dos carbonos ativados, estimar parÃmetros de transferÃncia de massa e simular o comportamento breakthrough dos sistemas estudados. Foram avaliadas as propriedades fÃsico-quÃmicas e o teor de poliaromÃticos apÃs o tratamento. Os resultados confirmaram a eficiÃncia dos carbonos ativados para utilizaÃÃo em processos de reduÃÃo do teor de compostos poliaromÃticos de ONP. Na terceira e Ãltima parte deste trabalho foram estudadas as propriedades fÃsico-quÃmicas e resistÃncia oxidativa de bioderivados (biodiesel e biolubrificantes) do Ãleo de mamona. O uso de antioxidantes aumentou de 6 a 15 vezes a estabilidade das amostras de biodiesel. Os estudos de estabilidade dos biolubrificantes hidrogenados com os melhores antioxidantes mostraram elevaÃÃo do perÃodo de induÃÃo em 10 vezes. / In this work, the methods for evaluation and modification of petroleum-based and bio-based products were studied. In the first part of this study, the adsorption of C8 aromatics in commercial molecular sieves was evaluated. The separation of xylene isomers is an important issue in the petrochemical industry. Headspace and chromatographic pulse techniques were used to measure experimental equilibrium data. This approach is very useful for the selection of adsorbents, as well as in the investigation of selectivity variation, with respect to composition and process temperature. The adsorption selectivities of multicomponent mixtures determined by the chromatographic pulse method were in agreement with the values obtained using headspace technique. The aforementioned values indicate the character of para-selectivity in zeolites Y (αpx/ox ~ 4) and beta (αpx/ox ~ 2), as well as the ortho-selectivity for the mordenite zeolites (αox/px ~ 1.5). In the second part of this study, we studied the adsorption of polyaromatics using model samples and heavy naphthenic oils (HNO). The experiments with model solutions were used to study the capacity of polycyclic aromatic adsorption to evaluate the process parameters and to select the most promising adsorbents (Norit 830W and Norit 1240 Plus), with samples for the evaluation of the HNO. Therefore, the samples were characterized and the HNO had a high content of polyaromatics hydrocarbons (8.2% m/m). Through column experiments, it was possible to evaluate the adsorption capacity of activated carbons, estimating parameters and mass transfers to simulate the breakthrough behavior of the above systems. We evaluated the physicochemical properties and the content of polyaromatics after treatment. The results confirmed the efficiency of activated carbons as an alternative process to reduce polyaromatics content of a HNO. In the third part of this study, we analyzed the physicochemical properties and the oxidation resistance of bio-based products (biodiesel and biolubricants) of the castor oil. Hence, the use of antioxidants increased from 6 to 15 times the stability of castor oil biodiesel. Stability studies of hydrogenated biolubricants with the best antioxidants showed an elevation of the induction period by 10 times.
75

Remoção de compostos ácidos do petróleo em diferentes tipos de carvão ativado / Acid compounds removal from oil crude in different types of activated carbons

Araújo, Anderson Barros Caixeta 29 February 2016 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-09-20T11:12:34Z No. of bitstreams: 2 Dissertação - Anderson Barros Caixeta Araújo - 2016.pdf: 3153002 bytes, checksum: ba1e261db38d81f09762632dfc921e8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-20T11:58:38Z (GMT) No. of bitstreams: 2 Dissertação - Anderson Barros Caixeta Araújo - 2016.pdf: 3153002 bytes, checksum: ba1e261db38d81f09762632dfc921e8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-20T11:58:39Z (GMT). No. of bitstreams: 2 Dissertação - Anderson Barros Caixeta Araújo - 2016.pdf: 3153002 bytes, checksum: ba1e261db38d81f09762632dfc921e8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The naphthenic acids comprise a complex mixture of carboxylic acids that are present in petroleum. They are directly responsible for the oil acidity and its corrosiveness in liquid phase during the refining process. Such compounds are also presents in the derivatives, causing several problems to product quality. A possible way of removing these acids from those oil fractions is using the adsorption process in porous solids, as activated carbons. There are few studies about the removal of naphthenic acids on coals. For this reason, we chose four types of activated carbons for adsorption tests, and they coal babassu, palm kernel, coconut and of Bahia ox bone. In order to assess the possibility of further removing acidic compounds, the four carbons were subjected to a chemical treatment with concentrated sodium hydroxide. Physical and chemical analyzes were performed in order to promote the characterization of all adsorbents, showing that the treatment previously mentioned was leading to an increase in the adsorption capacity of the coals. The adsorption experiments with commercial batch naphthenic acid solution showed that the treated ox bone char had the highest retention efficiency, which is the adsorbent used to construct the adsorption isotherms. The isotherms were better adjusted by Langmuir model, revealing the chemisorption of character adsorptive process. The thermodynamic data showed that the process is spontaneous and endothermic, is favored by increasing the temperature. Regarding the crude oil sample, batch adsorption experiments were conducted in such a way as to determine the removal efficiency of class O2 and reducing the Total Acid Number (IAT). The results spectrometry FTICR ix MS Pasta, they showed that all coals chemically treated were able to remove more acidic compounds in relation to their untreated related. The raw coals babassu oil, palm oil and coconut Bahia showed a potential for adsorption of nitrogen compounds from oil, given that there was a decrease in its class in the class chart. As a final analysis, all the coals were evaluated for their ability to lower oil IAT, it was found that the ox bone char treated again achieved the best result, reducing by 70% the value of the IAT. / Os ácidos naftênicos correspondem à complexa mistura de ácidos carboxílicos presentes no petróleo, responsáveis diretamente pela sua acidez e pela sua corrosividade em fase líquida durante o refino. Tais compostos também estão presentes nas frações destiladas do petróleo, causando diversos problemas na qualidade final do produto. Uma alternativa para a remoção desses ácidos das frações destiladas é por meio da adsorção em materiais porosos, como os carvões ativados. Poucos são os estudos a respeito da remoção de ácidos naftênicos em carvões. Por esta razão, foram escolhidos quatro tipos de carvões ativados para os ensaios de adsorção, sendo eles carvão de babaçu, dendê, coco da Bahia e osso de boi. A fim de avaliar a possibilidade de uma maior remoção de compostos ácidos, os quatro carvões foram submetidos a um tratamento químico com solução concentrada de hidróxido de sódio. Análises físico-químicas foram realizadas com o intuito de promover a caracterização de todos os adsorventes, revelando que o tratamento anteriormente citado foi preponderante para um aumento na capacidade adsortiva dos carvões. Os ensaios de adsorção em batelada com solução comercial de ácidos naftênicos mostraram que o carvão de osso de boi tratado apresentou a maior eficiência de retenção, sendo este o adsorvente utilizado para a construção das isotermas de adsorção. As isotermas foram melhor ajustadas pelo Modelo de Langmuir, revelando o caráter de quimiossorção do processo adsortivo. Os dados termodinâmicos mostraram que o processo é espontâneo e endotérmico, sendo mais favorecido pelo aumento da temperatura. Em relação à amostra de petróleo bruto, ensaios de adsorção em batelada foram conduzidos de tal forma a averiguar a eficiência na remoção da classe O2 e na redução do Índice de Acidez Total (IAT). Os resultados de Espectrometria de Massas FT-ICR MS, mostraram que todos os carvões tratados quimicamente conseguiram remover mais compostos ácidos em relação a seus correlatos não tratados. Os carvões brutos de babaçu, dendê e coco da Bahia apresentaram uma potencialidade para adsorção de compostos nitrogenados do petróleo, haja vista que houve a diminuição desta classe no gráfico de classes. Como análise final, todos os carvões foram avaliados quanto suas capacidades de redução do IAT do petróleo, em que foi constatado que o carvão de osso de boi tratado novamente conseguiu o melhor resultado, reduzindo em 70% o valor do IAT.
76

Petroleômica : caracterização de petróleos nacionais por espectrometria de massas de altíssima resolução: que os compostos ácidos podem revelar sobre o petróleo / Petroleomics : characterization of Brazilian crude oils by ultra high resolution mass spectrometry: what acidic compounds can reveal about petroleum

Pereira, Rosana Cardoso Lopes, 1959- 22 August 2018 (has links)
Orientadores: Marcos Nogueira Eberlin, Eugenio Vaz dos Santos Neto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T16:54:54Z (GMT). No. of bitstreams: 1 Pereira_RosanaCardosoLopes_D.pdf: 5832219 bytes, checksum: 88820b58f8b6360b78a6aa2f16ceb943 (MD5) Previous issue date: 2012 / Resumo: Este trabalho consistiu na aplicação de tecnologia que se encontra hoje na vanguarda do conhecimento: a Petroleômica via ESI FT-ICR MS, com o objetivo de caracterizar as mais diversas classes de compostos polares ácidos presentes em amostras representativas de óleos de bacias brasileiras. O propósito ambicioso foi o de focalizar aspectos relacionados à toda cadeia de valor da indústria do petróleo, desde a geração do óleo até o seu refino, visando contribuir para novos estudos de interesse às atividades de upstream e downstream da PETROBRAS e, principalmente, fomentar a integração dos conhecimentos das diferentes áreas, o que contribuirá para ganhos de produtividade da empresa. A técnica ESI FT-ICR-MS mostrou-se uma técnica rápida e adequada para acompanhar as alterações verificadas na composição de amostras de petróleo, fornecendo subsídios a partir de uma caracterização única, para estudos diversos, abrangendo toda a cadeia de valor da indústria do petróleo. As alterações composicionais de óleos e extratos obtidos em experimentos de maturação artificial por hidropirólise de matéria orgânica dos tipos I e III foram avaliadas, evidenciando o potencial da técnica para utilização em estudos cinéticos. O estudo de biodegradação utilizando trinta amostras de óleos da Bacia Potiguar evidenciou que a técnica é sensível as variações de composição dos compostos polares que ocorrem em função do processo de biodegradação, e as amostras puderam ser agrupadas de acordo com o grau de biodegradação através da utilização de ferramentas quimiométricas (PCA). A partir dos dados de caracterização obtidos por ESI FT-ICR MS, foi possível agregar informações úteis para o entendimento de comportamentos diferenciados frente à tendência de formação de emulsão/gel durante a produção e frente à corrosão durante o refino / Abstract: This work focuses on the application of a technology that is cutting edge: Petroleomics by ESI FT-ICR MS with the goal of characterizing the large variety of acidic polar compound classes present in representative petroleum samples from Brazilian basins. The ambitious proposal was to focus on aspects related to the whole petroleum industry chain, since crude oil generation up to its processing in refinery units, to contribute to state-of-the-art studies of interest to upstream and downstream activities in PETROBRAS and mostly to encourage the knowledge integration, i.e. to form or blend the information into a whole, to UNITE, accessing high levels of productivity. The ESI FT-ICR MS technique exhibits characteristics like fast response, resolution, selectivity and sensibility, which make it suitable to monitor the changes in composition of petroleum samples and because of its unique and comprehensive characterization attained, to help different studies in the whole petroleum industry chain. The compositional alteration observed in extracts and oils during artificial maturation experiments by hydrouspyrolysis of organic matter types I and III were evaluated showing the potential of the technique to kinetic studies. Biodegradation studies were performed on 30 petroleum samples from Potiguar Basin and the results showed that the technique is sensitive to the variations on the composition of the polar compounds that occur as a result of the biodegradation process, and additionally, that the samples can be grouped according to their biodegradation level by the use of chimiometric tools (PCA). Also from the characterization data from ESI FT-ICR MS analysis it was shown that very useful information can be provided to better understand the differences in the rheological and corrosion behaviors of petroleum samples / Doutorado / Quimica Analitica / Doutora em Ciências
77

Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures

Jin, Peng January 2013 (has links)
No description available.
78

Condensed phase membrane introduction mass spectrometry

Duncan, Kyle Daniel 17 December 2015 (has links)
Over the last few decades, membrane introduction mass spectrometry (MIMS) has been established as a robust tool for the on-line continuous monitoring of trace gases and volatile organic compounds. However, the range of amenable anlaytes has been limited by the need for molecules to pervaporate into a gaseous acceptor phase, or high vacuum environment of a mass spectrometer. This thesis expands the range of amenable analytes for MIMS to include larger, less volatile molecules (e.g., 200 to 500 Da), such as pharmaceuticals, persistent organic pollutants, and small biomolecules. This was achieved through the use of a liquid|membrane|liquid interface. We distinguish the technique from conventional MIMS, which uses a gaseous acceptor phase, by inserting the prefix ‘condensed phase’ to emphasize the use of a solvent acceptor phase – thus yielding CP-MIMS. An initial flow-cell interface with a methanol acceptor phase was characterized, yielding detection limits for model analytes in pptr to ppb, and analyte response times from 1-10 minutes. The flow cell interface was miniaturized into an immersion style CP-MIMS probe (~2 cm), which allowed for analysis of smaller volume samples and improved membrane washing capabilities. Comparable detection limits were observed for the immersion probe, however, it was noticed that significant analyte depletion was observed for samples under 2 mL. In addition, each of the developed membrane interfaces were observed to suffer from ionization suppression effects from complex samples when paired with ESI. Several strategies for mitigating ionization suppression using CP-MIMS are presented, including the use of a continuously infused internal standard present within the acceptor solvent. The developed CP-MIMS system was challenged with the analysis of naphthenic acids (a complex mixture of aliphatic carboxylic acids) directly in contaminated real-world samples. The method used negative ESI to rapidly screen and mass profile aqueous samples for naphthenic acids (as [M-H]-), with sample duty cycles ~20 min. However, it was found that Negative ESI did not differentiate hydroxylated and carboxylated analytes, and both species contributed signal to the total naphthenic acid concentration. To increase method specificity for carboxylic acids, barium ion chemistry was used in conjunction with positive ion tandem mass spectrometry. Common product ions were used to quantify carboxylated analytes, while a qualifier ion was used to confirm the functionality. The increased selectivity afforded by the barium ion chemistry was at the cost of a modest increase in detection limits. CP-MIMS has been established as a technique capable of the direct analysis of real-world samples, and shows promise as a rapid screening method for amenable environmental contaminants and/or biomolecules. / Graduate / 0486 / 0485 / kyle.duncan@viu.ca
79

Étude de la stabilité des émulsions et de la rhéologie interfaciale des systèmes pétrole brut/eau : influence des asphaltènes et des acides naphténiques / Study of the water in oil emulsions and interfacial rheology for crude oil/water systems : influence of asphaltenes and naphthenic acids

Flesinski, Lionel 14 December 2011 (has links)
La formation d'émulsions eau-dans-huile stables est un problème majeur rencontré par les pétroliers au niveau de la production mais aussi du raffinage. Afin d'essayer de prévoir ce phénomène, Total a développé une méthode de classement des huiles qui permet, à partir de leurs propriétés physico-chimiques, de déterminer a priori leur capacité à former ou non des émulsions stables. Cependant, les mécanismes interfaciaux sous-jacents ainsi que l’influence des molécules tensioactives du brut sur la stabilité des émulsions n’est pas très clair. Notre travail a consisté à étudier la contribution des acides naphténiques et des asphaltènes dans les phénomènes observés. L’étude d’huiles réelles a permis d’établir un lien entre la stabilité des émulsions et la formation à l'interface d'un gel 2D. Les études menées sur les huiles réelles dont les acides naphténiques ont été extraits ont permis de montrer que ces derniers, en compagnie de leurs formes ionisées, les naphténates, ont la capacité de réduire la stabilité des émulsions en diminuant la résistance du gel interfacial, ou même en empêchant sa formation. Les expériences réalisées sur les huiles réelles dépourvues d’asphaltènes ont permis de confirmer le rôle stabilisant des asphaltènes. Les résultats obtenus suggèrent que les asphaltènes s’adsorbent sur le gel 2D déjà formé par des tensioactifs passés de l’huile vers l’eau et le rapprochent ainsi de sa transition vitreuse. La résistance du gel interfacial s'en trouve alors augmentée, ce qui conduit à la formation d'émulsions plus stables. En croisant le classement industriel des bruts opéré par Total et les résultats de l’étude, un mécanisme global, régi par la compétition entre les acides naphténiques, les naphténates et les asphaltènes à l’interface E/H est proposé pour expliquer les différences de stabilité observées avec les différentes huiles. Lorsque les acides et les naphténates sont suffisamment concentrés, ils empêchent la formation du gel interfacial et les émulsions sont peu stables. Lorsqu’ils sont moins concentrés le rôle des asphaltènes peut alors devenir prépondérant en donnant une cohésion plus importante au gel qui se rapproche de sa transition vitreuse, ce qui conduit en général au renforcement de la stabilité des émulsions formées. / Water-in-crude oil emulsions are a major issue for oil companies in both production and refining facilities. Thanks to physical and chemical characterizations, Total set a classification which allows the decision of a crude oil ability to create stable emulsions. However the interfacial mechanisms implied and the influence of the indigenous surfactants of crude oil remain unclear. Our work consists in studying the naphthenic acids and asphaltenes contribution to the w/o emulsion stability. The study of realistic crude oils enabled the discovery of a link between the emulsion stability with the formation of a very particular interfacial behavior: a two-imensional gel. Experiments with desacidified oils have proven the destabilizing ability of naphthenic acids and their ionized form, naphthenates. They actually decrease the interfacial gel strength and can even prevent the gel formation. Asphaltenes-free crude oils have permitted to confirm the stabilizing role of asphaltenes. Rather than adsorbing directly on the interface, asphaltenes seem to adsorb on the interfacial gel already formed. The gel strength is thus increased and lead to higher emulsion stability. Thanks to these results and the industrial classification of crude oil developed by Total, a global mechanism explaining the emulsion stability process has been proposed. This mechanism is governed by the competition between asphaltenes, naphthenates and naphthenic acids at the water/oil interface. If the concentration of naphthenic acids and naphthenates is high enough, the interfacial gel cannot be formed and the emulsions are unstable. If the crude oil is not acidic enough, the asphaltenes influence increases dramatically and implies the strengthening of the gel which becomes closer to his glass transition. This generally leads to the formation of more stable emulsions.
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Novas formula??es de fluidos de corte: otimiza??o, propriedades e recupera??o do ?leo usado

Muniz, Cl?udia Alves de Sousa 12 November 2008 (has links)
Made available in DSpace on 2014-12-17T15:42:03Z (GMT). No. of bitstreams: 1 ClaudiaASM.pdf: 1242411 bytes, checksum: c3160a204092117e2180c02e3fd1b0bc (MD5) Previous issue date: 2008-11-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Cutting fluids are lubricants used in metal-mechanical industries. Their complex composition varies according to the type of operation carried out, also depending on the metals under treatment or investigation. Due to the high amount of mineral oil produced in Northeastern Brazil, we have detected the need to better use this class of material. In this work, two novel formulations have been tested, both based on naphthenic mineral oil and additives, such as: an emulsifying agent (A), an anticorrosion agent (B), a biocide (C) and an antifoam agent (D). Each formulation was prepared by mixing the additives in the mineral oil at a 700-rpm stirring velocity for 10 min, at 25?C, employing a 24 factorial planning. The formulations were characterized by means of density, total acid number (TAN), viscosity, flash point and anticorrosion activity. In a subsequent study, oil-in-water emulsions were prepared from these novel formulations. The emulsions were analyzed in terms of stability, corrosion degree, percentage of foam formation, conductivity, accelerated stability and particle size. The samples were appropriately labeled, and, in special, two of them were selected for featuring emulsion properties which were closer to those of the standards chosen as references (commercial cutting oils). Investigations were undertaken on the ability of NaCl and CaCl2 to destabilize the emulsions, at concentrations of 2%, 5% and 10%, at an 800-rpm stirring velocity for 5 min and temperatures of 25?, 40?, 50? and 60?C. The recovered oils were chemically altered by reincorporating the same additives used in the original formulations, followed by preparation of emulsions with the same concentrations as those of the initial ones. The purpose was to assess the possibility of reusing the recovered oil. The effluents generated during the emulsion destabilization step were characterized via turbidity index, contents of oil and grease, pH, and contents of anions and cations, observing compliance with the parameters established by the current environmental legislation (Brazil s CONAMA 357/05 resolution). It could be concluded that the formulations presented excellent physicochemical properties as compared to commercial cutting fluids, showing that the quality of the newly-prepared fluids is superior to that of the formulations available in the market, enabling technically and environmentally-safe applications / Fluidos de corte s?o lubrificantes usados nas ind?strias metal-mec?nicas. Possuem composi??es complexas que variam de acordo com o tipo de opera??o executada e com os metais a serem trabalhados. Levando-se em conta a grande quantidade de ?leo mineral produzido na regi?o nordeste, verificou-se a necessidade de melhor aproveit?-los. Neste trabalho desenvolveram-se duas formula??es usando-se como base ?leo mineral naft?nico e aditivos, tais como: emulsificante (A), anticorrosivo (B), biocida (C) e antiespumante (D). Cada formula??o foi preparada com a mistura dos aditivos ao ?leo mineral, sob agita??o de 700 rpm por 10 min, a 25?C, utilizando-se um planejamento fatorial 24. As formula??es foram caracterizadas atrav?s da densidade, ?ndice de acidez, viscosidade, ponto de fulgor e corros?o. Em seguida foram preparadas emuls?es O/A obtidas a partir das novas formula??es. Destas emuls?es estudou-se a estabilidade, grau de corros?o, percentual de espuma formado, condutividade, estabilidade acelerada e tamanho de part?culas. Escolheram-se as amostras F8 e F16 por apresentarem as propriedades das emuls?es mais pr?ximas dos padr?es escolhidos como refer?ncia (fluidos de corte comerciais). Realizou-se o estudo da quebra das emuls?es utilizando o NaCl e o CaCl2 , nas concentra??es de 2%, 5% e 10%, com agita??o durante 5 min, ? velocidade de 800 rpm, nas temperaturas de 25?, 40?, 50? e 60?C. Os ?leos recuperados foram readitivados com os mesmos aditivos utilizados nas formula??es iniciais. Em seguida, prepararam-se emuls?es nas mesmas concentra??es das emuls?es iniciais com o intuito de verificar se o ?leo recuperado poderia ser reutilizado. Os efluentes gerados durante a quebra das emuls?es foram caracterizados atrav?s da turbidez, teor de ?leos e graxas, pH, ?nions e c?tions, verificando-se enquadramento dos par?metros avaliados na legisla??o ambiental em vigor (Resolu??o CONAMA 357/05). As formula??es apresentaram ?timas propriedades f?sico-qu?micas quando comparadas com os fluidos de corte comerciais, mostrando, dessa forma, que os fluidos obtidos s?o de qualidade superior aos encontrados no mercado e podem ser utilizados com seguran?a t?cnica e ambiental

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