O principal resíduo da indústria de café solúvel é a borra de café, gerada após a extração de sólidos solúveis com água, sendo usualmente queimada em caldeiras para geração de energia para a própria indústria. Entretanto, este co-produto pode conter de 15 a 20 % de óleo, componente de grande interesse na indústria alimentícia. Em paralelo, na indústria de produção de óleos vegetais o solvente frequentemente utilizado é o hexano. Contudo, por este ser um derivado de combustíveis fósseis, alternativas para sua substituição por solventes mais amigáveis ao meio ambiente, que podem ser obtidos por via biotecnológica, estão sendo estudadas. Deste modo, o objetivo principal desta dissertação de mestrado foi a viabilização técnica do emprego de solventes alcoólicos no processo de extração de óleo de borra de café proveniente da indústria de processamento de café solúvel. Foram realizadas extrações sólido-líquido em um estágio para estudar a influência das variáveis de processo temperatura (60 a 90 °C), tipo de solvente (etanol, ET ou isopropanol, IPA) e a hidratação do solvente (absoluto ou azeotrópico) nas características das fases extrato e rafinado, em termos de rendimento de extração de óleo, de ácidos clorogênicos (ACG), de carboidratos totais, teor de proteínas e índice de solubilidade de nitrogênio (ISN) da fase rafinado. Pré-tratamento enzimático ao processo de extração também foi realizado para investigar a sua atuação sobre o rendimento de extração de óleo e ACG, além do ISN das fases rafinado obtidas na temperatura de 70 °C. De forma geral, pode-se inferir que a temperatura favorece a extração de compostos lipídicos, mas a hidratação do solvente prejudica a extração destes compostos pelo aumento da polaridade do solvente. Do mesmo modo, como o ET é mais polar que o IPA, o primeiro solvente proporcionou a obtenção de menores rendimentos de extração de óleo. A temperatura de processo também influenciou a extração de ACG, a qual foi beneficiada a temperaturas mais baixas pelo aumento da polaridade dos solventes utilizados. De tal forma, que a 60 °C, nos experimentos utilizando etanol azeotrópico obteve-se os menores rendimentos de extração de óleo, porém maior rendimento de extração de ACG. O pré-tratamento enzimático apresentou diferenças significativas nas características das fases extrato e rafinado. No entanto, somente os experimentos com etanol absoluto resultaram em rendimentos de extração de óleo economicamente viáveis. De fato, será relevante um estudo mais aprofundado das variáveis de pré-tratamento enzimático para obter resultados mais expressivos em relação à extração de compostos lipídicos. Diante dos dados experimentais obtidos, conclui-se que é tecnicamente viável o emprego de solventes alcoólicos no processo de extração de óleo de borra de café. Entretanto, nota-se que as condições de processo devem ser avaliadas minuciosamente com o objetivo de se obter altos rendimentos de extração de óleo com maior teor de ACG. / Spent coffee grounds are the main residues of the soluble coffee industry, which are generated after the extraction of soluble solids with water. They are generally burned in boilers to generate energy for the coffee industry. However, this residue may contain 15 to 20 % oil, a component of interest to the food industry. Hexane is the most common solvent used in the vegetable oil industry; however, as it is a fossil fuel byproduct, biotechnology alternatives that replace it by more environmental-friendly solvents are being studied. Therefore, the main objective of this study was to determine technical viability of alcoholic solvents in oil extraction of spent coffee grounds. Solid-liquid extractions were carried out in one stage in order to analyzed the influence of the variables of the process (temperature, 60 to 90 °C; type of solvent, ethanol, ET or isopropanol, IPA; and solvent hydration level, absolute or azeotropic degree) in the characteristics of extract and raffinate phases, in terms of yield of oil extraction, chlorogenic acids (CGA), total carbohydrates, protein content, and nitrogen solubility index (NSI) of the raffinate phase. Enzymatic pre-treatment in the extraction process was also carried out to assess its effect on the oil and CGA yields, as well as NSI in the raffinate phase obtained at 70 °C. In general, it could be inferred that temperature favored lipid extraction, but solvent hydration level negatively affected extraction due to the increased polarity of the solvent. Similarly, as ET is more polar than IPA, the former solvent enabled lower yield of oil. The temperature of the process also influenced CGA extraction, which was favored by lower temperatures and increased solvent polarity. Therefore, at 60 °C, in the trials using azeotropic ethanol, oil extraction yield was lower, and CGA yield was greater. Enzymatic pre-treatment showed significant differences in the characteristics of the extract and raffinate phases. However, only the trials with absolute ethanol led to economically viable oil yields. In fact, further studies on pre-treatment variables of the enzymatic treatment should be carried out for more relevant results in relation to lipid compound extraction. Given the experimental data obtained here, it was concluded that the use of alcoholic solvents in oil extraction of spent coffee grounds is technically viable. However, the conditions of the process should be carefully analyzed for high yields of oil with greater levels of CGA to be obtained.

Las microalgas han demostrado ser la fuente de energía más económica. Además, reduce el dióxido de carbono, también tienen una mayor producción en un corto tiempo y menor espacio a diferencia de otros cultivos. Entre las más de 100 especies de microalgas, el Scenedesmus dimorphus es el que tiene mayor potencial. El objetivo de este trabajo de tesis fue determinar de qué manera con un medio de cultivo para Scenedesmus obliquus var. dimorphus (Turpin) se obtiene cantidad de biomasa y contenido de aceite. Inicialmente, el trabajo experimental consistió en la obtención de la cepa pura de Scenedesmus dimorphus (14 mL). Seguidamente, se realizó el escalamiento de cultivo desarrollándose de la siguiente manera: 100 mL, 250 mL, 500 mL, 1L, 2L y 5L, con el fin de determinar las curvas de crecimiento mediante el conteo celular de S. dimorphus con el uso de la cámara de Neubauer, obteniendo los siguientes resultados: 3’ 451,500 unidades celulares en 120 horas (Bayfolan Forte), 2’ 472,500 unidades celulares en 192 horas (BG-11) y 327,500 unidades celulares en 96 horas (Guillard). Concluyendo que el Bayfolan Forte se obtuvo un mejor resultado. A continuación, se realizó 5 cosechas, luego se usó el método de floculación mediante la utilización del sulfato de aluminio Al2(SO4)3 y posteriormente, para la extracción de aceites, se molió la biomasa seca (36.5 g) seguido por la extracción con disolvente en hexano/ isopropanol, y se obtuvo un total de 30 mL de lípidos. Finalmente, en la parte estadística se comprobó la validez de las hipótesis utilizando diferentes métodos, tales como: Anova, Tukey y T. Student.

This thesis deals with the stopping of hydration of alkali activated slag by organic solvents and investigates to what extent the selected organic solvent affects the results of the analyses. The solvents used were acetone, diethyl ether, ethanol, isopropanol and methanol, and this is because these are the most commonly used organic solvents in practice. Thermogravimetric analysis along with differential thermal analysis was used to assess the degree of influence of organic solvents on the alkali activated slag and Portland cement samples. Methanol and acetone affected the samples the most and the longer the sample was stored in the solvent, the more it reacted with the organic solvent. The adverse interaction of organic solvent was greatest for the Portland cement samples. Samples that were rinsed with diethyl ether prior to analysis had lower mass losses than samples that were not rinsed. In the case of alkali activated slag, it was found that the way in which the thermogravimetric results were affected by organic solvents was highly dependent on the activator used, with the smallest effect observed for Na2CO3 activation, while the largest effect was observed for NaOH activation at temperatures below 600 °C, and for higher temperatures for water glass activation.

Em ultimas décadas, a conversão de alcanos leves em suas correspondentes olefinas tem sido objeto de intensas pesquisas, impulsionadas inclusive pelo aumento crescente da demanda do propileno como um importante produto petroquímico. A desidrogenação oxidativa (ODH) do propano representa uma via alternativa promissor para a produção de propeno, ao apresentar-se como uma reação exotérmica e não limitada termodinamicamente. Diferentes óxidos suportados ou mistos têm sido desenvolvidos com a finalidade de aumentar a atividade e seletividade em relação as olefinas. Metais alcalinos são importantes agentes promotores que proporcionam uma melhor seletividade as olefinas devido a redução da acidez e aumento da basicidade da superfície do catalisador. A proposta deste presente trabalho foi desenvolver metodologias de síntese de catalisadores de oxido de vanádio suportado em aluminas de diferentes fases cristalinas e dopados com sódio ou potássio a fim de avalia-los em testes catalíticos de desidrogenação oxidativa do propano. Para tanto, foram utilizadas as seguintes técnicas de caracterização: volumetria N2, difratometria de raios X (DRX) e redução a temperatura programada (RTP). As características acidas e/ou básicas dos suportes e catalisadores foram avaliadas pelas reações de decomposição de isopropanol. / In recent decades, the conversion of light alkanes to their corresponding olefins has been the subject of intense research, mainly driven by the increasing demand of propylene as an important petrochemical product. Oxidative dehydrogenation (ODH) propane is a promising alternative way to propylene production, which it is presented as an exothermic reaction and not limited thermodynamically. Different supported or mixed oxides have been developed in order to increase the activity and selectivity to olefins. Alkali metals are important promoters, which provide improved selectivity to olefins due to reduction of acidity and increasing basicity of the catalyst surface. The purpose of the present study was to develop synthesis methods of vanadium oxide catalysts supported on alumina of the different crystalline phases and doped with sodium or potassium in order to evaluate them in catalytic tests of propane oxidative dehydrogenation. For in such a way, the following characterization techniques were used: N2 volumetry, X-ray diffractometry (XRD) and temperature programmed reduction (TPR). The properties acid and/or basic of supports and catalysts were evaluated by the isopropanol decomposition reaction.

Em ultimas décadas, a conversão de alcanos leves em suas correspondentes olefinas tem sido objeto de intensas pesquisas, impulsionadas inclusive pelo aumento crescente da demanda do propileno como um importante produto petroquímico. A desidrogenação oxidativa (ODH) do propano representa uma via alternativa promissor para a produção de propeno, ao apresentar-se como uma reação exotérmica e não limitada termodinamicamente. Diferentes óxidos suportados ou mistos têm sido desenvolvidos com a finalidade de aumentar a atividade e seletividade em relação as olefinas. Metais alcalinos são importantes agentes promotores que proporcionam uma melhor seletividade as olefinas devido a redução da acidez e aumento da basicidade da superfície do catalisador. A proposta deste presente trabalho foi desenvolver metodologias de síntese de catalisadores de oxido de vanádio suportado em aluminas de diferentes fases cristalinas e dopados com sódio ou potássio a fim de avalia-los em testes catalíticos de desidrogenação oxidativa do propano. Para tanto, foram utilizadas as seguintes técnicas de caracterização: volumetria N2, difratometria de raios X (DRX) e redução a temperatura programada (RTP). As características acidas e/ou básicas dos suportes e catalisadores foram avaliadas pelas reações de decomposição de isopropanol. / In recent decades, the conversion of light alkanes to their corresponding olefins has been the subject of intense research, mainly driven by the increasing demand of propylene as an important petrochemical product. Oxidative dehydrogenation (ODH) propane is a promising alternative way to propylene production, which it is presented as an exothermic reaction and not limited thermodynamically. Different supported or mixed oxides have been developed in order to increase the activity and selectivity to olefins. Alkali metals are important promoters, which provide improved selectivity to olefins due to reduction of acidity and increasing basicity of the catalyst surface. The purpose of the present study was to develop synthesis methods of vanadium oxide catalysts supported on alumina of the different crystalline phases and doped with sodium or potassium in order to evaluate them in catalytic tests of propane oxidative dehydrogenation. For in such a way, the following characterization techniques were used: N2 volumetry, X-ray diffractometry (XRD) and temperature programmed reduction (TPR). The properties acid and/or basic of supports and catalysts were evaluated by the isopropanol decomposition reaction.

Dans la synthèse des matériaux catalytiques, deux aspects orientent en particulier les recherches actuelles: le contrôle de taille afin d'obtenir des nanoparticules finement divisées et le contrôle précis de la morphologie. Dans cette étude, nous avons utilisé les milieux non aqueux pour élaborer des matériaux catalytiques à base d'oxydes des métaux de transition (Ti, Zr, Mn). Trois méthodologies ont été employées pour la préparation des solides à base de TiO2. La synthèse dans les nitrates fondus dopés avec différents anions permet un boncontrôle des propriétés texturales des matériaux et de la nature des plans cristallins exposés. Les préparations utilisant le nitrate d'ammonium stabilisé avec des molécules organiques azotées conduit à des solides présentant des tailles et des formes de particules variables en fonction de la nature du stabilisateur. Le traitement à reflux dans des solvants organiques polaires conduit à l'obtention des supports TiO2 de grandes surfaces spécifiques. Pour la valorisation catalytique de ces matériaux, deux réactions appliquées au domaine de la photocatalyse ont été employées: la production d'H2 par déshydrogénation du méthanol etl'oxydation photocatalytique de l'acide formique. La réaction modèle de décomposition del'isopropanol a été utilisée comme test de caractérisation des propriétés acido-basiques de nossystèmes. La technique de nitrates fondus a été également appliqué avec succès pourl'obtention en une seule étape des catalyseurs supportés Mn-Zr et Mn-Ti. Ces catalyseursmontrent une excellente activité pour l'oxydation totale de composés organiques volatils(COV).

In this study, polyelectrolyte membranes were prepared by layer-by-layer self-assembly on top of an interfacially polymerized polyamide substrate, and these thin-film-composite membranes were studied for pervaporative dehydration of ethylene glycol, ethanol and isopropanol. The performance of composite membranes based on polyethylenimine/poly(acrylic acid) (PEI/PAA) multilayers on a polyamide substrate showed good selectivity and stability for ethylene glycol dehydration. In order to understand the formation process of the polyelectrolyte multilayers, the growth of polyelectrolyte multilayers fabricated on the inner surface of cuvette was investiagted. The membrane surface became increasingly hydrophilic with an increase in the number of polyelectrolyte double layers, which favored water permeation for pervaporative dehydration of organic solvents. Water contact angle on the membrane surface decreased from 68?? to 20?? when 7 polyelectrolyte bilayers were deposited on the polyamide substrate. Although the (PEI/PAA) based polyelectrolyte membranes showed good performance for dehydration of ethylene glycol, these membranes did not perform well for the dehydration of ethanol and isopropanol at relatively high feed alcohol concentrations. This was found to be caused by insufficient stability of PEI/PAA bilayers and the polyamide substrate in the ethanol and isopropanol. To improve the performance of the composite membranes for dehydration of ethanol and isopropanol, the outermost surface layer was deposited with PEI, followed by crosslinking. A further improvement in the membrane selectivity was accomplished by substituting the PEI with partially protonated chitosan in the last few polyelectrolyte bilayers during membrane fabrication. It was demonstrated that using interfacially polymerized polyamide membrane as a substrate, polyelectrolyte membranes with less than 8 bilayers could be fabricated for the dehydration of alcohol and diol. This represents a siginificant advancement as a large number of polyelectrolyte bilayers (as many as 60) are often needed. Glutaraldehyde crosslinked polyelectrolyte self-assembled membranes comprising of chitosan and PAA were also prepared for isopropanol/water separation. The resulting membrane showed stable performance with good permeation flux and separation factor. The effects of crosslinking conditions (e.g., concentration and temperature of crosslinking agent, and crosslinking time) on the membrane performance were studied. Alternatively, using PEI as polycation, when anionic PAA was substituted with alginate in the last few polyelectrolyte bilayers during membrane fabrication, stable membranes with a good performance were obtained without the need of chemical crosslinking. The polyethylenimine/alginate self-assembly membranes showed good selectivity and stability for dehydration of ethanol. For instance, a permeation flux of 0.24 kg/(??? h) and a separation factor of 206 were obtained at room temperature at 10 wt% feed water concentration with a membrane comprising of 10 double layers of polyelectrolytes.

Ce travail montre la mise en œuvre d'une technique originale pour le chauffage rapide et bien contrôlé de catalyseurs sous forme de films minces déposés sur un structurant métallique. L'utilisation d'un système à induction électromagnétique adapté à un réacteur catalytique de type annulaire nous a permis d'étudier un certain nombre de matériaux catalytiques, déposés sur acier inoxydable, dans une perspective d'oxydation totale en CO2 et H2O de composés organiques volatiles (COV) présents dans l'air. La combustion de l'isopropanol et du toluène par l'oxygène de l'air a été étudiée en utilisant différents catalyseurs déposés sous forme de films minces: 1%Pt/Al2O3, 0,3%Pt/SnO2, 1%Pt/SnO2 et 1%Pt/YSZ. Les solides ont été préparés par imprégnation des oxydes correspondants par H2PtCl6 puis ont été déposés sur le support d'acier inoxydable par électrophorèse. Les principaux paramètres relatifs au mode de chauffage ont été étudiés de même que l'influence sur la conversion des COV de différents facteurs tels que la quantité de catalyseur, le pourcentage de platine ou la nature du support oxyde employé. Les informations fournies par ce système innovant ont également été comparées pour validation à celles obtenues à l'aide d'un système classique (microréacteur en quartz à lit traversé chauffé de manière conventionnelle) pour une réaction de référence qui est l'oxydation de CO en CO2. Le système décrit dans cette étude présente d'une part un intérêt pratique pour le traitement rapide de contaminations accidentelles de l'air ambiant, mais est aussi un très bon moyen d'obtenir des paramètres cinétiques fiables dans le domaine des catalyseurs en films minces utilisés dans de nombreux réacteurs structurés

Two small combustion systems, methyl hydroperoxide (CH3OOH) and 2-propanol ((CH3)2CHOH), were studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO), which combines photoelectron spectroscopy and photoionization mass spectrometry to detect coincident photoelectron-photoion pairs. In the photon energy range of 11.4–14.0 eV, energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions. The lowest-energy dissociation channel is the formation of the cation of the smallest “QOOH” radical, CH2OOH+. A statistical rate model fitted to the experimental data yields a 0 K appearance energy of 11.647 ± 0.005 eV for the CH2OOH+ ion, and a 74.2 ± 2.6 kJ mol–1 mixed experimental-theoretical 0 K heat of formation for the CH2OOH radical. The proton affinity of the Criegee intermediate, CH2OO, was also obtained from the heat of formation of CH2OOH+ (792.8 ± 0.9 kJ mol–1) to be 847.7 ± 1.1 kJ mol–1, reducing the uncertainty of the previously available computational value by a factor of 4. RRKM modeling of the higher-energy fragmentation processes, supported by Born–Oppenheimer molecular dynamics simulations, found that the HCO+ fragment ion is produced through a roaming transition state; H3O+ is formed in a consecutive process from the CH2OOH+ fragment ion; and direct C–O fission of the molecular ion leads to the methyl cation. Experimentally, 2-propanol has been found to dissociate primarily into CH2CHOH+, CH3CHOH+, CH3CHCH3+, and, as a minor product, into (CH3)2COH+ ions within a photon energy range of 10.0–13.1eV. There are interesting dissociation dynamics involving breaking the C–¬C bond: the lowest energy product (CH3 loss) is quickly outcompeted by a kinetically favored CH4 loss. At low internal energies of < 0.3 eV, the loss of CH4 dominates through a roaming pathway, when the leaving CH3 abstracts a hydrogen atom from the other methyl group. At higher energy, the direct loss of CH3• quickly takes over as its transition state is much less tight and, thus, it is kinetically favored. The statistical model fitted to the experimental data yielded the appearance energy corresponding to the thermochemical limit for the CH3-loss dissociation and the 0 K heats of formation of the CH3CHOH+ ion was found to be in good agreement with ATcT values and with our previous study on ethanol.

Ce travail montre la mise en œuvre d'une technique originale pour le chauffage rapide et bien contrôlé de catalyseurs sous forme de films minces déposés sur un structurant métallique. L'utilisation d'un système à induction électromagnétique adapté à un réacteur catalytique de type annulaire nous a permis d'étudier un certain nombre de matériaux catalytiques, déposés sur acier inoxydable, dans une perspective d'oxydation totale en CO2 et H2O de composés organiques volatiles (COV) présents dans l'air. La combustion de l'isopropanol et du toluène par l'oxygène de l'air a été étudiée en utilisant différents catalyseurs déposés sous forme de films minces: 1%Pt/Al2O3, 0,3%Pt/SnO2, 1%Pt/SnO2 et 1%Pt/YSZ. Les solides ont été préparés par imprégnation des oxydes correspondants par H2PtCl6 puis ont été déposés sur le support d'acier inoxydable par électrophorèse. Les principaux paramètres relatifs au mode de chauffage ont été étudiés de même que l'influence sur la conversion des COV de différents facteurs tels que la quantité de catalyseur, le pourcentage de platine ou la nature du support oxyde employé. Les informations fournies par ce système innovant ont également été comparées pour validation à celles obtenues à l'aide d'un système classique (microréacteur en quartz à lit traversé chauffé de manière conventionnelle) pour une réaction de référence qui est l'oxydation de CO en CO2. Le système décrit dans cette étude présente d'une part un intérêt pratique pour le traitement rapide de contaminations accidentelles de l'air ambiant, mais est aussi un très bon moyen d'obtenir des paramètres cinétiques fiables dans le domaine des catalyseurs en films minces utilisés dans de nombreux réacteurs structurés / This study shows the development of an innovative technique for a fast and well-controlled heating of catalysts deposited as thin films on a metallic support. The use of an electromagnetic induction system fitted to an annular catalytic reactor enabled us to study some catalytic materials deposited on stainless steel. The target application was the abatement of volatile organic compounds (VOCs) in the air. Isopropyl alcohol and toluene combustion by the oxygen was studied on various thin films catalysts, i.e. : 1%Pt/Al2O3, 0,3%Pt/SnO2, 1%Pt/SnO2 et 1%Pt/YSZ. Solids were prepared by wet impregnation of the corresponding oxides by H2PtCl6 and were deposited on the stainless steel support using an electrophoretic deposition technique. The main parameters of the heating system were investigated as well as the influence on VOCs abatement of various parameters such as the thickness of catalyst film, the platinum amount and the nature of the oxide. For validation purpose, the data provided by this innovative system were also compared to the ones provided by a classical one (quartz plug-through microreactor heated in a conventional way) in a reference reaction which was CO oxidation into CO2. The system described in this study shows on the one hand a real practical interest for fast remediation of indoor air polluted by VOCs, and on the other hand is a very powerful tool for obtaining kinetic data about thin layer catalysts used in many structured reactors