Estudos termoanalíticos de alguns aditivos alimentares da classe dos realçadores de sabor foram desenvolvidos visando avaliar sua estabilidade e resistência durante o preparo de alimentos a quente assim como investigar os eventuais intermediários de decomposição que poderiam resultar destes processos. Os sais foram obtidos de fontes industriais ou sintetizados e submetidos à caracterização por análise elementar, espectrometria vibracional na região do infra-vermelho, termogravimetria/termogravimetria derivada, análise térmica diferencial e em alguns casos, calorimetria exploratória diferencial. Foram estudados o ácido glutâmico e seus sais de amônio, lítio e sódio mono e dissubstituídos. Em todos os casos observou-se uma conversão a piroglutamato após desidratação dos sais monossubstituídos, a qual ocorre via a a-carboxila. A estabilidade térmica destes sais foi da ordem de 190-200 °C. No caso dos sais dissubstituídos de lítio e sódio não houve conversão ao piroglutamato pois as duas carboxilas estão salificadas. Os glutamatos de magnésio, cálcio estrôncio e bário, também foram preparados e investigados quanto ao seu comportamento térmico. Os sais se formaram na estequiometria 2:1 (ligante:metal), apresentando águas de hidratação em número característico e foram estáveis até 190- 200 °C. Finalmente foram estudados os mecanismos de decomposição térmica do inosinato-monofosfato de sódio e do guanilato-monofosfato de sódio, dois nucleotídeos que apresentam a propriedade de realçar o sabor de alimentos. Ambos apresentaram elevado grau de hidratação, para o qual foi possível distinguir mecanismos característicos de desidratação. A decomposição dos sais anidros ocorreu com saída do grupo purínico, seguida da decomposição do restante da molécula e formação de pirofosfato de sódio como resíduo final. / Thermal analytical studies of some food addictives of the flavor enhancer class were developed in order to evaluate their stability and resistance to the hot cooking process, as well as to identify the intermediaries of thermal decomposition that could remain at the end of such processes. The salts were obtained from industrial sources or synthesized and characterized by elemental analysis, infra-red spectroscopy, thermogravimetry/derivative thermogravimetry, differential thermal analysis and in some opportunities to differential scanning calorimetry. The glutamic acid and its ammonium, lithium and sodium salts mono and disubstituted were investigated. In all cases a conversion to pyroglutamate has been observed in the free acid and its monosubstituted salts after dehydration. The conversion undergoes by the ?-carboxyl group. The thermal stability was observed to be as high as 190-200 °C. In the case of the lithiu m and sodium dissubstituted salts any conversions to pyroglutamates were observed, once both carboxyl groups were salified. Magnesium, calcium, strontium and barium glutamates has also been synthesized and investigated in relation to its thermal behavior. The salts were formed in the 2:1 stoichiometry (ligand:metal), presenting hydration waters in a characteristic content and showed to be stable up to 190-200 °C. Finally the thermal decomposition mechanisms of dissodium inosinatemonophosphate and dissodium guanilate-monophosphate two nucleotides with flavor enhancement properties in food were also investigated. Both presented high degree of hydration, to which it was possible to propose a water release mechanism. The decomposition of the anhydrous salts occurred with release of the purine group followed by the decomposition of the rest of the molecule generating sodium pyrophosphate as residue.

Estudos termoanalíticos de alguns aditivos alimentares da classe dos realçadores de sabor foram desenvolvidos visando avaliar sua estabilidade e resistência durante o preparo de alimentos a quente assim como investigar os eventuais intermediários de decomposição que poderiam resultar destes processos. Os sais foram obtidos de fontes industriais ou sintetizados e submetidos à caracterização por análise elementar, espectrometria vibracional na região do infra-vermelho, termogravimetria/termogravimetria derivada, análise térmica diferencial e em alguns casos, calorimetria exploratória diferencial. Foram estudados o ácido glutâmico e seus sais de amônio, lítio e sódio mono e dissubstituídos. Em todos os casos observou-se uma conversão a piroglutamato após desidratação dos sais monossubstituídos, a qual ocorre via a a-carboxila. A estabilidade térmica destes sais foi da ordem de 190-200 °C. No caso dos sais dissubstituídos de lítio e sódio não houve conversão ao piroglutamato pois as duas carboxilas estão salificadas. Os glutamatos de magnésio, cálcio estrôncio e bário, também foram preparados e investigados quanto ao seu comportamento térmico. Os sais se formaram na estequiometria 2:1 (ligante:metal), apresentando águas de hidratação em número característico e foram estáveis até 190- 200 °C. Finalmente foram estudados os mecanismos de decomposição térmica do inosinato-monofosfato de sódio e do guanilato-monofosfato de sódio, dois nucleotídeos que apresentam a propriedade de realçar o sabor de alimentos. Ambos apresentaram elevado grau de hidratação, para o qual foi possível distinguir mecanismos característicos de desidratação. A decomposição dos sais anidros ocorreu com saída do grupo purínico, seguida da decomposição do restante da molécula e formação de pirofosfato de sódio como resíduo final. / Thermal analytical studies of some food addictives of the flavor enhancer class were developed in order to evaluate their stability and resistance to the hot cooking process, as well as to identify the intermediaries of thermal decomposition that could remain at the end of such processes. The salts were obtained from industrial sources or synthesized and characterized by elemental analysis, infra-red spectroscopy, thermogravimetry/derivative thermogravimetry, differential thermal analysis and in some opportunities to differential scanning calorimetry. The glutamic acid and its ammonium, lithium and sodium salts mono and disubstituted were investigated. In all cases a conversion to pyroglutamate has been observed in the free acid and its monosubstituted salts after dehydration. The conversion undergoes by the ?-carboxyl group. The thermal stability was observed to be as high as 190-200 °C. In the case of the lithiu m and sodium dissubstituted salts any conversions to pyroglutamates were observed, once both carboxyl groups were salified. Magnesium, calcium, strontium and barium glutamates has also been synthesized and investigated in relation to its thermal behavior. The salts were formed in the 2:1 stoichiometry (ligand:metal), presenting hydration waters in a characteristic content and showed to be stable up to 190-200 °C. Finally the thermal decomposition mechanisms of dissodium inosinatemonophosphate and dissodium guanilate-monophosphate two nucleotides with flavor enhancement properties in food were also investigated. Both presented high degree of hydration, to which it was possible to propose a water release mechanism. The decomposition of the anhydrous salts occurred with release of the purine group followed by the decomposition of the rest of the molecule generating sodium pyrophosphate as residue.

Surfactant related recovery processes are of increasing interest and importance because of high oil prices and the urge to meet energy demand. High oil prices and the accompanying revival of EOR operations have provided academia and industry with great opportunities to test alkaline surfactant polymer (ASP) methods on a field scale and to develop novel surfactant systems that can improve the performance of such EOR processes. This dissertation intends to discuss both opportunities through two unique projects, the development of novel surfactants for EOR applications and the design for an alkaline/surfactant/polymer (ASP) field pilot. In Section I of this dissertation, a novel series of anionic Gemini surfactants are carefully synthesized and systematically investigated. The remarkable abilities of Gemini surfactants to influence oil-water interfaces and aqueous solution properties are fully demonstrated. These surfactants are shown to have great potential for application in EOR processes. A wide range of Gemini structures (C₁₄ to C₂₄ chain length, -C2- and -C4- spacers, sulfate and carboxylate head groups) was synthesized and shown to have high aqueous solubility, with Krafft points below 20°C. The critical micelle concentrations (CMC) for these new molecules are measured to be orders of magnitude lower than their conventional counterparts. The significantly more negative Gibbs free energy for Gemini surfactant drives the micellization process and results in ultralow CMC. An adsorption study of Gemini surfactants at air-water and solid-water interfaces shows their superior surface activity from tighter molecular packing, and attractive characteristics of low adsorption loss at the solid surface. All anionic Gemini surfactants synthesized have an extraordinary tolerance to salinity and/or hardness. No phase separation or precipitation occurs in the aqueous stability tests, even in the presence of extremely high concentrations of mono- and/or di-valent ions. Moreover, ultra-low IFT values are reached under these conditions for Type I microemulsion systems, at very low surfactant concentrations. The stronger molecular interaction between the Gemini and conventional surfactants offers synergy that promotes aqueous stability and interfacial activity. Gemini molecules with short spacers are capable of giving rise to high viscosities at fairly low concentrations. The rheological behavior can be explained by changes in the micellar structure. A molecular thermodynamic model is developed to study anionic Gemini surfactants aggregation behavior in solution. The model takes into account of the head group-counter-ion binding effect and utilizes two simplified solutions to the Poisson-Boltzmann equation. It properly predicts the CMC of the surfactants synthesized and can be easily expanded to investigate other factors of interest in the micellization process. Section II of this dissertation studies chemical formulation design and implementation for an oilfield where an alkaline/surfactant/polymer (ASP) pilot is being carried out. A four-step systematic design approach, composed of a) process and material selection; b) formulation optimization; c) coreflood validation; 4) lab-scale simulation, was successfully implemented and could be easily transferred to other EOR projects. The optimal chemical formulation recovered over 90% residual oil from Berea coreflood. Lab-scale simulation model accurately history matches the coreflood experiment and sets the foundation for pilot-scale numerical study. Different operating strategies are investigated using a pilot-scale model, as well as the sensitivities of project economics to various design parameters. A field execution plan is proposed based on the results of the simulation study. A surface facility conceptual design is put together based on the practical needs and conditions in the field. Key lessons learned throughout the project are summarized and are invaluable for planning and designing future pilot floods. / text

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O grafeno à atualmente o tÃpico mais corrente em fÃsica da materia condensada e ciÃncia dos materiais e foi isolado pela primeira vez a menos de quatro anos. O grafeno tem sido proposto como um material alternativo aos nanotubos de carbono em diversas aplicaÃÃes, devido a sua fÃcil sintetizaÃÃo e seu baixo custo. A fim de explorar uma potencial aplicaÃÃo dessas nanoestruturas em dispositivos eletrÃnicos, atravÃs de cÃlculos de primeiros princÃpios baseados na teoria do funcional da densidade, estudamos a interaÃÃo entre uma superfÃcie de grafeno e Ãtomos alcalinos (Li, Na e K) e halogÃnios (Cl, I e I2). Verificamos que a adsorÃÃo desses Ãtomos na superfÃcie do grafeno provoca significativas modificaÃÃes na estrutura eletrÃnica do grafeno. Observamos uma grande transferÃncia de carga entre os Ãtomos alcalinos (halogÃnios) e a superfÃcie do grafeno. Essas transferÃncias foram da ordem de 0,65-0,85 e- dos Ãtomos alcalinos para o grafeno e 0,37 (0,27) e- do grafeno para o Ãtomo de cloro (iodo). Os metais alcalinos apresentaram uma maior estabilidade sobre o centro de um hexÃgono do grafeno, tendo energias de ligaÃÃo entre -1,47 e -1,03 eV, onde a ordem de intensidade à dada por Li > K > Na. Essa predisposiÃÃo por um sÃtio especÃfico nÃo foi observada para os dois halogÃnios estudados. O Ãtomo de cloro apresentou uma maior estabilidade quando adsorvido sobre um Ãtomo da superfÃcie do grafeno, com energia de ligaÃÃo da ordem de 0,98 eV, no entanto, isso nÃo foi visto no caso do Ãtomo de iodo onde energias de ligaÃÃo equivalentes para todos os sÃtios estudados foram encontradas da ordem de 0,42 eV. A molÃcula I2 tambÃm nÃo apresentou uma predileÃÃo por uma sitio especÃfico da superfÃcie do grafeno, mas mostrou-se mais estÃvel quando adsorvida com seu eixo perpendicular ao plano do grafeno. / Graphene is currently the hottest topic in condensed-matter physics and materials science and was isolated less than four years ago. Graphene layers have been proposed as alternative materials for replacing carbon nanotubes in some applications, due to its easy synthesis and low costs. In order to explore potential applications of those nanostructures in electronic devices, through first principles based on the density functional theory, we studied the interaction between graphene surface and alkaline (Li, Na and K) and halogens (Cl, I and I$_2$ ) atoms. We verified that the adsorption of these atoms on the graphene surface cause significant modifications in the graphene electronic structure. We observed a large charge transfer between the alkaline (halogens) atoms and graphene surface. These charge transfers were found to be 0,65 - 0,85 e- from the alkaline atoms to graphene and 0,37 (0,27) e- from the graphene to chlorine (iodine) atoms. The alkaline atoms presented a larger stability on the center of one of the graphene hexagons, presenting binding energy in the range -1, 47 and -1, 03 eV, where the order of intensity is given by Li > K > Na. This predisposition for a specific site was not observed for the twostudied halogens. The chlorine atom present the larger stability when adsorbed on a top atom of the graphene surface with binding energy about 0, 98 eV, however this behavior was not be seen in the iodine atom case where equivalent binding energies for all the studied sites were found to be about 0,42 eV. The I2 molecule also does not present predilection for a specific site on the graphene surface, however it showed more stable when adsorbed with its axis perpendicular to the graphene surface plane.

Dans le cadre de la politique de réduction des émissions de gaz toxiques tels que les composés organiques volatils (COV) et les oxydes d'azote (NOx), cette étude portait sur la mise au point de catalyseurs exempts de métaux nobles, efficaces pour l'élimination simultanée des COV (propène) et des NOx en présence d'un excès d'oxygène (milieu pauvre). Deux traitements ont été envisagés : d'une part nous avons étudié la réaction d'oxydation totale du propène et d'autre part les réactions simultanées d'oxydation du propène et de réduction des NOx. Le choix s'est reporté sur les matériaux hydrotalcites qui, après calcination, permettent d'obtenir un mélange d'oxydes ayant des propriétés intéressantes en catalyse. Dans un premier temps, des catalyseurs massiques à base de Cu, de Mg et de Al ont été synthétisés par voie hydrotalcite. Nous avons pu mettre en évidence que les espèces cuivriques sous formes de petits agrégats de CuO très dispersés à la surface sont actifs pour la réduction des NOx alors que les ions CU²⁺ sous forme de cristallites de CuO sont plus actifs dans l'oxydation du propène. Afin d'améliorer les performances catalytiques de ces catalyseurs, l'incorporation de l'élément Fe dans ces matériaux a été réalisée. Pour la réaction de réduction des NOx en présence de C₃H₆, la coexistence du fer et du cuivre dans un même matériau décale la fenêtre de température de conversion des NOx vers de plus basses températures mais également diminue la conversion de NO. Par ailleurs, en vue d'accroître les valeurs de conversion de NOx, le catalyseur qui convertit le mieux les NOx a été promu par des métaux alcalins. Cs et Na ont montré un effet promoteur tandis que K a exercé un effet inhibiteur dans la réaction de réduction des NOx. Dans la dernière partie de ce travail, une introduction à l'oxydation catalytique des suies et à l'élimination simultanée du propène et des NOx en présence de suies a été envisagée. Une autre partie du travail de thèse a concerné les particules atmosphériques qui ont été collectées au Liban durant une tempête désertique provenant du désert Arabe, le but étant d'évaluer le changement morphologique et chimique qui peut avoir lieu au cours du transport à longue distance. La caractérisation de ces particules par microcopie électronique à balayage couplée à un Spectromètre à Dispersion d'Energie a montré que les grosses particules sont riches en oxydes métalliques (notamment en Si, Al, Mg, Fe, Ca...). Sur les particules fines et ultrafines nous avons pu mettre en évidence la formation d'oligomères d'organonitrates et d'organosulfates. Or, ces organonitrates proviennent de la réaction entre les COV et les NOx. / This thesis was done within the politics of reducing the emissions of toxic gases such as volatile organic compounds (VOC) and nitrogen oxides (NOx). This study aimed to optimize efficient catalysts, prepared in the absence of noble metals, for the simultaneous elimination of VOC (propylene) and NOx under excess of oxygen (lean condition). Hydrotalcite solids were chosen because of the interesting properties of the oxides obtained by their calcination. Two treatments were performed : on the one hand the propylene oxidation alone, on the other propylene oxidation and NOx reduction simultaneously. Cu, Mg and Al - based catalysts were prepared by the hydrotalcite route. The as-prepared solids were proven to be efficient in the NOx reduction due to the presence of small aggregates of well dispersed CuO on the surface. However the CU²⁺ ions in the forms of crystallites were active in the propylene reaction. In order to improve the catalytic activity, Fe element was then incorporated into the solids to substitute a part or all of the Al element and the effects were studied. In the selective catalytic reduction of NOx by the C₃H₆ the introduction of iron species into the structure lowered the temperature of complete C₃H₆ conversion but also reduced the NOx conversion. Moreover, in order to improve the NOx conversion, the catalyst that exhibited the best reduction of NOx was promoted by alkaline letals. Cs and Na showed a promoting effect while K displayed an inhibotory effect. Finally, an introduction to soot oxidation and the simultaneous elimination of propylene and NOx in the presence of soot was conducted. Another part of this work concerned atmospheric particles collected in Lebanon during dust-rich days originating from the Arabian Desert. Transformations in the morphology and chemical composition of aerosols were assessed by Scanning Electron Microscopy (SEM) equipped with an Energy Dispersive X-ray system. The results showed that coarse particles are rich in metal oxides (Si, Al, Mg, Fe, Ca...). However, over fine and ultrafine particles, the formation of organonitrates and organosulfates oligomers was observed. Yet, organonitrates sprung from the reaction between VOC and NOx.

SILVA, José Júnior Alves da. Adsorção de átomos alcalinos e halogênios em uma superfície de Grafeno: um estudo de primeiros princípios. 2008. 85 f. Dissertação (mestrado) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2008. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-05-13T22:42:26Z No. of bitstreams: 1 2008_dis_jjasilva.pdf: 4132276 bytes, checksum: 961eed37504f3bed4fe8ed917e245554 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2014-05-14T18:27:16Z (GMT) No. of bitstreams: 1 2008_dis_jjasilva.pdf: 4132276 bytes, checksum: 961eed37504f3bed4fe8ed917e245554 (MD5) / Made available in DSpace on 2014-05-14T18:27:16Z (GMT). No. of bitstreams: 1 2008_dis_jjasilva.pdf: 4132276 bytes, checksum: 961eed37504f3bed4fe8ed917e245554 (MD5) Previous issue date: 2008 / Graphene is currently the hottest topic in condensed-matter physics and materials science and was isolated less than four years ago. Graphene layers have been proposed as alternative materials for replacing carbon nanotubes in some applications, due to its easy synthesis and low costs. In order to explore potential applications of those nanostructures in electronic devices, through first principles based on the density functional theory, we studied the interaction between graphene surface and alkaline (Li, Na and K) and halogens (Cl, I and I$_2$ ) atoms. We verified that the adsorption of these atoms on the graphene surface cause significant modifications in the graphene electronic structure. We observed a large charge transfer between the alkaline (halogens) atoms and graphene surface. These charge transfers were found to be 0,65 - 0,85 e- from the alkaline atoms to graphene and 0,37 (0,27) e- from the graphene to chlorine (iodine) atoms. The alkaline atoms presented a larger stability on the center of one of the graphene hexagons, presenting binding energy in the range -1, 47 and -1, 03 eV, where the order of intensity is given by Li > K > Na. This predisposition for a specific site was not observed for the twostudied halogens. The chlorine atom present the larger stability when adsorbed on a top atom of the graphene surface with binding energy about 0, 98 eV, however this behavior was not be seen in the iodine atom case where equivalent binding energies for all the studied sites were found to be about 0,42 eV. The I2 molecule also does not present predilection for a specific site on the graphene surface, however it showed more stable when adsorbed with its axis perpendicular to the graphene surface plane. / O grafeno é atualmente o tópico mais corrente em física da materia condensada e ciência dos materiais e foi isolado pela primeira vez a menos de quatro anos. O grafeno tem sido proposto como um material alternativo aos nanotubos de carbono em diversas aplicações, devido a sua fácil sintetização e seu baixo custo. A fim de explorar uma potencial aplicação dessas nanoestruturas em dispositivos eletrônicos, através de cálculos de primeiros princípios baseados na teoria do funcional da densidade, estudamos a interação entre uma superfície de grafeno e átomos alcalinos (Li, Na e K) e halogênios (Cl, I e I2). Verificamos que a adsorção desses átomos na superfície do grafeno provoca significativas modificações na estrutura eletrônica do grafeno. Observamos uma grande transferência de carga entre os átomos alcalinos (halogênios) e a superfície do grafeno. Essas transferências foram da ordem de 0,65-0,85 e- dos átomos alcalinos para o grafeno e 0,37 (0,27) e- do grafeno para o átomo de cloro (iodo). Os metais alcalinos apresentaram uma maior estabilidade sobre o centro de um hexágono do grafeno, tendo energias de ligação entre -1,47 e -1,03 eV, onde a ordem de intensidade é dada por Li > K > Na. Essa predisposição por um sítio específico não foi observada para os dois halogênios estudados. O átomo de cloro apresentou uma maior estabilidade quando adsorvido sobre um átomo da superfície do grafeno, com energia de ligação da ordem de 0,98 eV, no entanto, isso não foi visto no caso do átomo de iodo onde energias de ligação equivalentes para todos os sítios estudados foram encontradas da ordem de 0,42 eV. A molécula I2 também não apresentou uma predileção por uma sitio específico da superfície do grafeno, mas mostrou-se mais estável quando adsorvida com seu eixo perpendicular ao plano do grafeno.