abstract: Membrane technology is a viable option to debottleneck distillation processes and minimize the energy burden associated with light hydrocarbon mixture separations. Zeolitic imidazolate frameworks (ZIFs) are a new class of microporous metal-organic frameworks with highly tailorable zeolitic pores and unprecedented separation characteristics. ZIF-8 membranes demonstrate superior separation performance for propylene/propane (C3) and hydrogen/hydrocarbon mixtures at room temperature. However, to date, little is known about the static thermal stability and ethylene/ethane (C2) separation characteristics of ZIF-8. This dissertation presents a set of fundamental studies to investigate the thermal stability, transport and modification of ZIF-8 membranes for light hydrocarbon separations. Static TGA decomposition kinetics studies show that ZIF-8 nanocrystals maintain their crystallinity up to 200○C in inert, oxidizing and reducing atmospheres. At temperatures of 250○C and higher, the findings herein support the postulation that ZIF-8 nanocrystals undergo temperature induced decomposition via thermolytic bond cleaving reactions to form an imidazole-Zn-azirine structure. The crystallinity/bond integrity of ZIF-8 membrane thin films is maintained at temperatures below 150○C. Ethane and ethylene transport was studied in single and binary gas mixtures. Thermodynamic parameters derived from membrane permeation and crystal adsorption experiments show that the C2 transport mechanism is controlled by adsorption rather than diffusion. Low activation energy of diffusion values for both C2 molecules and limited energetic/entropic diffusive selectivity are observed for C2 molecules despite being larger than the nominal ZIF-8 pore aperture and is due to pore flexibility. Finally, ZIF-8 membranes were modified with 5,6 dimethylbenzimidazole through solvent assisted membrane surface ligand exchange to narrow the pore aperture for enhanced molecular sieving. Results show that relatively fast exchange kinetics occur at the mainly at the outer ZIF-8 membrane surface between 0-30 minutes of exchange. Short-time exchange enables C3 selectivity increases with minimal olefin permeance losses. As the reaction proceeds, the ligand exchange rate slows as the 5,6 DMBIm linker proceeds into the ZIF-8 inner surface, exchanges with the original linker and first disrupts the original framework’s crystallinity, then increases order as the reaction proceeds. The ligand exchange rate increases with temperature and the H2/C2 separation factor increases with increases in ligand exchange time and temperature. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2017

Submitted by Fernanda Rodrigues de Lima (fernanda.rlima@ufpe.br) on 2018-08-20T20:30:39Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Débora Dolores Nascimento.pdf: 3594688 bytes, checksum: cdf7df39006953035bd1e74095fb8d37 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-08-28T18:14:14Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Débora Dolores Nascimento.pdf: 3594688 bytes, checksum: cdf7df39006953035bd1e74095fb8d37 (MD5) / Made available in DSpace on 2018-08-28T18:14:15Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Débora Dolores Nascimento.pdf: 3594688 bytes, checksum: cdf7df39006953035bd1e74095fb8d37 (MD5) Previous issue date: 2017-05-26 / FACEPE / A carbamazepina (CBZ) é um derivado tricíclico do iminoestilbeno com atividade farmacológica antiepiléptica. Entre os problemas deste fármaco está a sua autoindução com a necessidade de administração de até 4 vezes por dia, além da alta incidência de reações adversas, o que provavelmente está relacionado com a sua baixa solubilidade, visto que pertence à classificação biofarmacêutica de classe II. Dessa maneira, a tecnologia farmacêutica auxilia na redução de alguns desses problemas como, por exemplo, através da adsorção da CBZ a um excipiente inovador para que auxilia com a sua solubilidade e altere sua liberação, modulando e prolongando a dissolução do fármaco. Assim, esse trabalho objetivou desenvolver e caracterizar sistemas formados entre a CBZ e uma estrutura organometálica chamada ZIF-8, com a finalidade de ser empregada nos estudos de pré-formulação de forma farmacêutica de liberação prolongada para o tratamento da epilepsia. Os sistemas foram obtidos após agitação do fármaco e da ZIF-8 em diferentes solventes (metanol, etanol, e etanol:H₂O 61%) e proporções molares para que fosse escolhido o melhor meio reacional, através da melhor eficiência de incorporação. As caracterizações dos sistemas desenvolvidos foram realizadas, em seguida, através várias técnicas analíticas para assegurar a obtenção do sistema, procedendo com os ensaios de dissolução in vitro sob condições sink para verificar o comportamento da liberação da CBZ quando adsorvido à ZIF-8 em diferentes pH’s e em meios com presença e ausência de tensoativo. Os perfis de dissolução foram analisados através da área sob a curva (AUC), eficiência de dissolução (ED%), modelo-independente através do fator de similaridade (ƒ2). Por meio do método desenvolvido o escolhido para obtenção foi o realizado com etanol:H₂O 61% como solvente, na proporção molar 1:1 após 3 horas de agitação sem intervalos. Através das análises térmicas pode-se comprovar a obtenção do sistema, indicando que o mesmo também pode influenciar positivamente na estabilidade térmica do fármaco. Os espectros de FT-IR, difratogramas de DR-X e demais análises realizadas, corroboraram com os resultados, confirmando a formação do sistema CBZ-ZIF-8. O estudo de dissolução possibilitou verificar modulação da liberação do fármaco independente do pH utilizado, obtendo resultados de uma liberação máxima de 36,2% em pH 1,2 com 1% de lauril sulfato de sódio (LSS), contra 17,7%, 12,5% e 11,2% quando submetido aos meios sem LSS, com pH 1,2, pH 4,5 e pH 7,6, respectivamente, durante o período de 24 horas. O presente trabalho através dos resultados de liberação prolongada independente de pH, trouxe informações relevantes para o desenvolvimento de formas farmacêuticas de liberação modificada que utilize CBZ como insumo farmacêutico ativo. / Carbamazepine (CBZ) is a tricyclic derivative of iminostilbene with pharmacological antiepileptic activity. Among the problems of this drug is its self-induction with the need to administer up to 4 times a day, in addition to the high incidence of adverse reactions, which is probably related to its low solubility, since it belongs to the class II biopharmaceutical classification. Thus, pharmaceutical technology assists in the reduction of some of these problems, for example by adsorbing CBZ to an innovative excipient, which assists with its solubility and alters its release, modulating and prolonging the dissolution of the drug. Thus, this work aimed to develop and characterize systems formed between CBZ and an organometallic structure called ZIF-8, with the purpose of being used in the preformulation studies of pharmaceutical form of extended release for the treatment of epilepsy. The systems were obtained after agitation of the drug and ZIF-8 in different solvents (methanol, ethanol, and ethanol: H₂O 61%) and molar ratios to the best reaction medium chosen, through the best incorporation efficiency. The characterization of the developed systems was then performed through several analytical techniques to ensure the system was obtained, proceeding with the in vitro dissolution tests under sink conditions to verify the CBZ release behavior when adsorbed to ZIF-8 at different pH's And in media with presence and absence of surfactant. The dissolution profiles were analyzed through the area under the curve (AUC), dissolution efficiency (ED%), model-independent through the similarity factor (ƒ2). Using the developed method the chosen one was obtained with ethanol: H₂O 61% as solvent, in the 1: 1 molar ratio after 3 hours of agitation without intervals. Through the thermal analysis, it is possible to prove the system, indicating that it can also positively influence the thermal stability of the drug. The FT-IR spectra, DR-X diffractograms and other analyzes, corroborated the results, confirming the formation of the CBZ-ZIF-8 system. The dissolution study allowed to verify the modulation of the drug release independent of the pH used, obtaining results of a maximum release of 36.2% in pH 1.2 with 1% of sodium lauryl sulfate (LSS), against 17.7% 12.5% and 11.2% when submitted to the media without LSS, with pH 1.2, pH 4.5 and pH 7.6, respectively, during the 24 hour period. The present work through the results of independent release of pH, has brought important information for the development of pharmaceutical forms of modified release that uses CBZ as active pharmaceutical ingredient.

Metal-organic frameworks (MOFs) are porous crystalline materials built by metal clusters coordinated to organic ligands. Synthesis of MOFs has attracted considerable attention in recent decades, owing to its potential for a wide range of applications such as gas separation, dye adsorption, and catalysis, etc. The development of MOF membranes further enhances the potential of this type of material in industrial applications. Membrane fabrication methods, including in-situ growth, seeded secondary growth, interfacial growth, and vapor-phase deposition, have been widely studied. However, most of these methods either require a complicated synthesis procedure or are timeconsuming. Recently, the electrochemical synthesis has emerged as a highly promising approach to fabricate MOF membranes in a scalable manner, because it allows shorter synthesis time, milder synthesis condition, continuous reaction, and crystal self-healing. In this thesis, for the first time, an aqueously cathodic deposition (ACD) approach was developed to fabricate ZIF-8 type of MOF membranes without the addition of any supporting electrolyte or modulator. The fabrication process used 100% water as the sole solvent, and a low-defect density membrane was obtained in only 60 min under room temperature without any pre-synthesis treatment. The membrane exhibited superior performance in C3H6/C3H8 separation with C3H6 permeance of 182 GPU and selectivity of 142, making it sit at the upper bound of permeance versus selectivity graph, outperforming the majority of the published data up to 2019. Notably, this approach used an extremely low current density (0.13 mA cm-2) operated under a facile apparatus setup, enabling an attractive method for environmentally friendly, energy-efficient, and scalable MOF membrane fabrications. This work demonstrates the enormous potential of aqueously electrochemical deposition of the MOF membrane in future research.

Volumetric adsorption experiments were conducted over three sorbates in Zeolitic Imidazolate Framework – 8 (ZIF-8). The sorption isotherms were measured at low temperatures. The study included carbon monoxide sorption in ZIF-8, xenon in ZIF-8, and methane sorption in ZIF-8. As a metal-organic framework that has been investigated thoroughly for its remarkable characteristics, ZIF-8 interactions with the above three sorbates has revealed some new features. Each of these systems offered a unique opportunity to study the physical properties of the sorbate and ZIF-8 and the thermodynamic responses of the system for its unique characteristics. The fundamental understating of sorbents-sorbate not only reveals some of the remarkable properties but also opens up new frontiers for researches in practical applications such as gas storage separation and other sorption-based fields of interest. The investigation into CO-ZIF-8 system has confirmed some of the predictions made on a similar system and analysis on the ZIF-8 structure. The measured adsorption isotherms have confirmed the existence of three pre-saturation subs steps, which were explained in terms of effects from the structural transition and polarity of the sorbate. The behavior of isosteric heat of adsorption and the equilibration time revealed a strong connection between steps in the isotherm and the structural changes of ZIF-8 due to organic linker rotation and volume expansion, also known as “Gate-Opening” in some cases. In both Xe-ZIF-8 and CH4 -ZIF-8 systems, the sorption isotherms revealed two substeps before the saturation. This is the first time such a feature was resolved experimentally in these systems although many previous studies have predicted the feature. The experimental observations on characteristics of the Xe -ZIF-8 system are also verified by computer simulations. Unlike the CO-ZIF-8 system, Xe-ZIF-8 interactions do not trigger the organic linker rotation of ZIF-8 structure, but it influenced the expansion of the ZIF-8 structure. In CH4 – ZIF-8 system the isotherms’ substeps were not as steep as Xe system but the loading dependence of isosteric heat of adsorption and equilibration time revealed features that are similar to CO. The lack of sorption-combined structural analysis of CH4-ZIF-8 prevent us from concluding the actual nature of the changes occurring which are related to the substeps and other thermodynamic and kinetic features. In all three systems, our measurements of the adsorption kinetics, we observed a non-monotonic behavior of the equilibration time as a function of sorbent loading. For CO the loading dependence of equilibration time exhibit peaks at loadings that correspond to the intermediate and higher loading sub-steps, and CH4 showed similar behavior at the loading corresponds to its intermediate substep region. The sharp peaks can be interpreted as packing rearrangement of adsorbed phase molecule in both cases and for CO there may be some contributions from the linker flipping and structural transition. The structural effect of kinetics is yet to be confirmed by a structural analysis for the CH4 system.

In this master thesis project, attempts were made to synthesize, pore size tailor, and characterize ZIF-8 and several mixed-linker ZIF structures to improve capture of the greenhouse gasses CH4, CO2, and SF6. Three experimental linkers, 2-methylbenzimidazole, 2-aminobenzimidazole, and 5-nitrobenzimidazole were chosen to gradually substitute 2-methylimidazole as the linker in ZIF-8.  This substitution was intended to gradually reduce pore sizes and possibly adding functionality to the apertures present in ZIF-8 (three different series). The methods of synthesis were first evaluated by performance and modified. Three series of ZIF-hybrids were then synthesized and characterized using PXRD, FTIR, 1HNMR, SEM, extensive sorption measurements, and subsequent modeling to evaluate any success tailoring the hybrid ZIF apertures to increase gas sorption. After modifying synthesis conditions, the undertaking was deemed a success as all three linkers were possible to incorporate to some degree. Hybrid ZIFs were mostly XRD-crystalline. The cleaning process was deemed sufficient. Linker incorporation was not complete but increased with the added linker. Sodalite topology was confirmed in ZIF-8 samples and confirmed as modified in hybrid ZIFs. The hybrid ZIFs did indeed show altered sorption results and surprisingly promising results regarding gas selectivity (favoring sorption of one gas over that of another).

Yes / Arsenic (As) contamination of surface water has become a global concern, especially for the third world countries, and it is imperative to develop advanced materials and an effective treatment method to address the issue. In this paper, iron doped ZIF-8@MXene (Fe-ZIF-8@MXene) was prepared as a potential adsorbent to effectively and simultaneously remove As(III/V) from wastewater. To investigate this, Fe-ZIF-8@MXene was characterized before and after the removal of mixed As(III/V). The results of Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), specific surface area (BET) and point of zero charge (pHpzc) showed that Fe-ZIF-8@MXene was prepared successfully and kept a stable structure after As(III) and As(V) adsorption. The particle size of Fe-ZIF-8@MXene was in the range of 0.5 μm to 2.5 μm, where its BET was 531.7 m2/g. For both contaminants, adsorption was found to follow pseudo-second-order kinetics and was best-fitted by the Langmuir adsorption model with correlation coefficients (R2) of 0.998 and 0.997, for As(III) and As(V), respectively. The adsorbent was then applied to remove As from two actual water samples, giving maximum removal rates of 91.07% and 98.96% for As(III) and As(V), respectively. Finally, removal mechanisms for As(III/V) by Fe-ZIF-8@MXene were also explored. During the adsorption, multiple complexes were formed under the effect of its abundant surface functional groups involving multiple mechanisms, which included Van der Waals force, surface adsorption, chemical complexation and electrostatic interactions. In conclusion, this study demonstrated that Fe-ZIF-8@MXene was an advanced and reusable material for simultaneous removal of As(III/V) in wastewater.

Au cours de ces dernières années, la microfluidique est devenue une technologie attrayante pour la synthèse en écoulement continu de dispersions colloïdales de nanocristaux. Ce procédé permet un contrôle optimal des paramètres de synthèse, offre une très bonne reproductibilité, et la possibilité de transposition à grande échelle. Dans une première partie, nous avons développé des synthèses microfluidiques et écologiques de cristaux ZIF 8, adaptables à une grande échelle de production, avec un écoulement monophasique ou biphasique (eau/alcane). La technologie microfluidique permet la synthèse rapide (10 min) de cristaux ZIF-8 avec une large variation de taille de particules (de 300 à 900 nm) simplement en faisant varier les paramètres expérimentaux (débit, température, ...). Les cristaux de ZIF-8 obtenus sont de forme géométrique dodécaèdrique rhombique, de structure cristalline sodalite et leur surface spécifique est d’environ 1700 m2/g. Puis, les propriétés catalytiques des particules ZIF-8 ont été évaluées. Des 3-cyanocoumarines et des cyanoesters α,β-insaturés ont été synthétisés avec des rendements variant de 89 à 95% via la réaction de Knoevenagel utilisant les particules ZIF-8 comme catalyseur hétérogène. Les particules de ZIF-8 peuvent être recyclées au minimum cinq fois. Dans la seconde partie de ce mémoire, nous avons synthétisé des QDs CdS dopé Mn2+ et Cu+ recouverts d’une coquille ZnS en microréacteur tubulaire avec un écoulement monophasique ou biphasique (eau/alcane). Différents paramètres expérimentaux (temps de séjour, température, pH, rapport molaire des précurseurs, concentration et nature des précurseurs, …) ont été évalués afin d’optimiser les propriétés optiques. Les QDs CdS dopé Mn2+ présentent uniquement l’émission de fluorescence liée à la transition 4T1→6A1 et leur rendement quantique de fluorescence est voisin de 10%. L’introduction d’une coquille ZnS en écoulement monophasique permet d’améliorer les propriétés optiques et de réduire les défauts des surfaces des QDs 6%Mn:CdS/ZnS (émission à 590 nm et rendement quantique de 20 %). L’introduction d’une coquille ZnS à la périphérie des QDs Cu:CdS ne permet pas d’améliorer de manière significative le rendement quantique de fluorescence. Dans la dernière partie, la synthèse en microréacteur avec écoulement monophasique ou biphasique (eau/alcane) de QDs ZnS dopé Mn2+ a été développée. Les QDs obtenus possèdent un rendement quantique de 13% s’ils sont préparés en écoulement monophasique / In recent years, microfluidics has become an attractive technology for the continuous flow synthesis of colloidal nanocrystals. This technology allows a good control of the synthesis parameters, a good reproducibility and the possibility of the application on a large scale. In a first part, we have developed continuous and ecological syntheses of the ZIF-8 crystals for the large scale, either with a monophasic or a biphasic flow (water/alkane). The microfluidic technology allows the fast synthesis (10 min) of ZIF-8 crystals over a wide size range (from ca. 300 to 900 nm) simply by varying the experimental parameters (flow rates, temperature,…). ZIF-8 crystals with the stable rhombic dodecahedron shape, of sodalite structure and with a high specific surface area (ca. 1700 m2.g-1) were obtained. Next, the catalytic properties of ZIF-8 crystals were evaluated. These particles were demonstrated to be an efficient heterogeneous catalyst for the Knoevenagel synthesis of α,β-unsaturated cyanoesters and of 3-cyanocoumarins using 2-hydroxy aromatic aldehydes and ethyl cyanoacetate as starting materials (yields ranging from 89 to 95%). The ZIF-8 particles can be recycled at least five times with negligible changes in catalytic performances. In the second part, we synthesized the Mn2+ or Cu+-doped CdS QDs coated with a ZnS shell in a tubular microreactor using a monophasic or a biphasic flow (water/alkane). Various experimental parameters (time, temperature, pH, molar ratio, concentration and nature of the starting materials) were evaluated to optimize the optical properties of the dots. The obtained Mn2+ doped CdS QDs exhibited a photoluminescence emission related to the 4T1 → 6A1 transition with quantum yields higher than 10%. The introduction of a ZnS shell with the monophasic flow allows to improve the optical properties and to reduce the surface defects of the 6% Mn:CdS/ZnS QDs (strong emission at 590 nm and quantum yields of ca. 20%). The introduction of a ZnS shell on the surface of Cu doped CdS QDs does not significantly improve the quantum yields. Finally, the synthesis of Mn2+-doped ZnS QDs with monophasic or biphasic flow (water/alkane) was developed. The dots have a photoluminescence quantum yield of 13% if they are prepared in a monophasic water flow

Made available in DSpace on 2014-12-17T15:36:52Z (GMT). No. of bitstreams: 1 NelsonAML.pdf: 877661 bytes, checksum: 9f0e44b26c1eea9bd528ee3676051107 (MD5) Previous issue date: 2008-04-17 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In the behavioral paradigm of discriminative avoidance task, both short and long-term memories have been extensively investigated with behavioral and pharmacological approaches. The aim of the present study was to evaluate, using the abovementioned model, the hippocampal expression of zif-268 - a calcium-dependent immediate early gene involved with synaptic plasticity process - throughout several steps of memory formation, such as acquisition, evocation and extiction. The behavioral apparatus consisted of a modified elevaated plus-maze, with their enclosed arms disposed in "L". A pre-exposure to the maze was made with the animal using all arms enclosed, for 30 minutes, followed by training and test, during 10 minutes each. The between sections interval was 24h. During training, aversive stimuli (bright light and loud noise) were actived whenever the animals entered one of the enclosed armas (aversive arm). Memory acquisiton, retention and extinction were evaluated by the percentage of the total time spent exploring the aversive arm. The parameters evaluated (time spent in the arms and total distance traveled) were estimated with an animal tracking software (Anymaze, Stoelting, USA). Learning during training was estimated by the decrease of the time spent exploring the aversive arm. One hour after the beginning of each section, animals were anaesthetized with sodium-thiopental (i.p.) and perfused with 0.9% heparinized saline solution followed by 4% paraformaldehyde. Brains were cryoprotected with 20% sucrose, separeted in three blocks and frozen. The middle block, containing the hippocampus, was sectioned at 20 micro meters in the coronal plane and the resutant sections were submitted to zif-268 immunohistochemistry. Our results show an increased expression of zif-268 in the dentate gyrus (DG) during the evocation and extinction stages. There is a distinct participation of the DG during the memory evocation, but not during its acquisition. Inaddition, all hippocampal regions (CA1, CA3 and DG) presented an increased zif-268 expression during the process of extinction. / No paradigma comportamental da esquiva discriminativa, as mem?rias de curto e de longo prazo t?m sido extensivamente estudadas tanto comportamental quanto farmacologicamente. O objetivo do presente estudo foi avaliar, usando o modelo supracitado, a express?o hipocampal de zif-268 - gene imediato dependente de c?lcio implicado em processos de plasticidade sin?ptica - ao longo das diversas etapas da forma??o da mem?ria, como aquisi??o, evoca??o e extin??o. O aparato comportamental consistiu de um labirinto em crum elevado modificado, com seus bra?os fechados dispostos em "L". Uma pr?-exposi??o ao labirinto foi feita com os animais usando os quatro bra?os fechados, com dura??o de 30 minutos, seguida de um treino e de um teste, cada qual com dura??o de 10 minutos. O intervalo entre as sess?es foi de 24 horas. Durante o treino, um est?mulo aversivo (luz e ru?do intensos) era acionado sempre que os animais entravam em um dos bra?os fechados (bra?o aversivo). A aquisi??o, reten??o e extin??o da mem?ria foram avaliados pelo percentual de tempo total gasto explorando o bra?o aversivo. Os par?metros avaliados (tempo nos bra?os e dist?ncia percorrida) foram registrados por um software de rastreamento de animais (Anymaze, Stoelting, USA). O aprendizado durante o treino foi estimado pelo decr?scimo do tempo gasto explorando o bra?o aversivo. Uma hora ap?s o in?cio de cada sess?o, os animais foram anestesiados com uma overdose de tiopental s?dico (i.p.) e perfundidos com solu??o salina heparinizada 0.9% seguida de paraformalde?do a 4%. Os enc?falos foram crioprotegidos com solu??o de sacorose a 20%, separados em tr?s blocos e congelados. O bloco do meio, contendo o hipocampo, foi seccionado a 20 micro metros no plano coronal e as sec??es resultantes foram ent?o submetidas ? imunohistoqu?mica para zif-268. Nossos resultados evidenciam um aumento da express?o de zif-268 no giro denteado (GD) durante asetapas de evoca??o e extins?o. H? uma participa??o distinta no GD durante a evoca??o e extin??o da mem?ria, mas n?o durante a aquisi??o. Al?m disso, todas as ?reas hipocampais (CA1, CA3 e GD) apresentam uma eleva??o da express?o de zif-268 durante o processo de extin??o

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-09-21T18:06:41Z No. of bitstreams: 1 sergiorodriguestavaresfilho.pdf: 12924949 bytes, checksum: e801383f9a72858db012935c840d4d15 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-09-22T15:21:43Z (GMT) No. of bitstreams: 1 sergiorodriguestavaresfilho.pdf: 12924949 bytes, checksum: e801383f9a72858db012935c840d4d15 (MD5) / Made available in DSpace on 2017-09-22T15:21:43Z (GMT). No. of bitstreams: 1 sergiorodriguestavaresfilho.pdf: 12924949 bytes, checksum: e801383f9a72858db012935c840d4d15 (MD5) Previous issue date: 2017 / O elemento zinco apresenta inúmeras aplicações e vantagens, devido à sua baixa toxicidade e sua biocompatibilidade. Alguns compostos, como os hidroxissais (HSL) e os hidróxidos duplos lamelares (HDL), os carboxilatos lamelares e as MOF, demonstram ser excelentes materiais com diversos potenciais de aplicabilidades. Algumas dessas aplicações são os processos de intercalação, adsorção e catálise. Nesse trabalho, foram investigados os processos de catálise da produção de biodiesel pelo acetato de zinco (um carboxilato lamelar), os processos de intercalação de moléculas tensoativas e das porfirinas aniônicas de ferro(III) pelos hidroxissais e os hidróxidos duplos lamelares, as propriedades adsortivas do ZIF-9 e os processos de esfoliação de uma série de carboxilatos de zinco lamelares e das moléculas tensoativas intercaladas em HDL e HSL. A fim de conduzir todo o estudo e essas investigações, foram feitos cálculos de estrutura eletrônica baseados na Teoria do Funcional da Densidade (DFT) a partir do pacote Quantum Espresso. No caso dos processos de esfoliação dos carboxilatos de zinco e de intercalação/esfoliação das moléculas tensoativas, uma comparação de funcionais de troca e correlação (PBE e vdW-DF) e do método semiempírico DFT-D2 foi feita para a contabilização das forças de van der Waals desses sistemas. Esse mesmo estudo metodológico foi feito para as propriedades do ZIF-9. Para o estudo de intercalação dos porfirinatos de ferro(III), um estudo do efeito de polarização de spin e da correção de Hubbard foi empregado para as propriedades estruturais e eletrônicas. Foi possível prever algumas propriedades de relevância como as energias de esfoliação para a família estudada de carboxilatos de zinco, assim como para os surfactantes intercalados em HDL e em HSL. As energias de adsorção das moléculas envolvidas nas reações de esterificação/transesterificação e a barreira de energia da formação de alcóxido permitiram a compreensão desses processos a nível atomístico. Uma elucidação estrutural foi também alcançada para as intercalações das moléculas tensoativas desidratadas e hidratadas, e dos porfirinatos de ferro(III). As propriedades adsortivas do ZIF-9 também foram estudadas, a fim de predizer a seletividade das moléculas estudadas (CO2, H2S, metanol e etanol). / The zinc element presents various applications and advantages due to its low toxicity and its biocompatibility. Some compounds, such as the hydroxide salts (LSH) and the double hydroxide salts (LDH), the layered carboxylates and the MOFs, are excelent materials with many potentials. Some of these applications are the intercalation processes, adsorption and catalysis. In this work, the catalysis of the biodiesel production with zinc acetate (a layered carboxylate) as the catalyst, the intercalation of surfactants and anionic iron(III) porphyrins in LDH and LHS, the adsorption properties of ZIF-9 and the exfoliation of a series of layered zinc carboxylates and the surfactants intercalated in LDH and LHS were investigated. In order to conduct all this study and these investigations, electronic structure calculations based on DFT by the Quantum Espresso package were performed. In the case of the exfoliation of the zinc carboxylates and the intercalation/exfoliation of the surfactants, a comparison of the exchange-correlation functionals (PBE and vdW-DF) and the semiempiric method DFT-D2 was made to capture the van der Waals forces of these systems. This same methodological study was made for the properties of ZIF-9. For the study of the intercalation of the anionic iron(III) porphyrins, the effect of the spin polarization and the Hubbard correction were investigated for the structural and electronic properties. Certain aspects could be predicted such as the exfoliation energies of the studied family of layered zinc carboxylates and also for the surfactants intercalated in LDH and LHS. The adsorption energies of the molecules involved in the esterification/transesterification reactions and the energy barrier of the alkoxide formation favored the comprehension of these processes at an atomistic scale. A structural elucidation was also achieved for the intercalation of the dehydrated and hydrated surfactants, and the anionic iron(III) porphyrins. The adsorption properties of ZIF-9 were also studied, in order to predict the selectivity of the studied molecules (CO2, H2S, methanol e ethanol).

Les travaux de cette thèse concernent la compréhension à l'échelle atomique des processus physico chimiques intervenant aux interfaces et dans des phases diluées. Pour commencer, nous avons étudié l'interaction entre la molécule 1,4-diazabicyclo [2.2.2]octane (DABCO) et un atome de gaz rare (He, Ne, Ar, Kr). Nous avons effectué une analyse systématique de ces systèmes, et nous en avons conclu que la méthode MP2 associée à une base diffuse est suffisamment précise pour décrire le système DABCO - Ar. Les surfaces d'énergie potentielle des complexes DABCO - gaz rare ont été calculées, ce qui nous a permis de réattribuer les spectres expérimentaux de ces espèces. Ensuite, nous nous sommes concentré sur les complexes DABCO - Arn (avec n = 2, 3, 4) neutres et ioniques. Nous avons montré que le DABCO interagi avec les atomes d'argon, et subit des déformations dues à l'effet de cette interaction faible sur ses modes de vibration. Par la suite, nous avons étudié les plus bas états électroniques du DABCO - Arn (n = 1, 2, 3). Nos résultats pourront être étendus à l'interprétation qualitative des études spectroscopiques et dynamiques des molécules de DABCO absorbés dans de grands agrégats d'argon. Enfin, nous avons étudié l'interaction entre l'imidazole et une couche d'or en présence de CO2. Nous avons montré que la molécule d'imidazole se fixe à l'agrégat d'or par une liaison covalente entre l'atome d'azote et un atome d'or, ainsi que des interactions faibles de type van der Waals entre les atomes d'hydrogène et la surface d'or. Nous avons déterminé que le site préférentiel pour l'interaction imidazole - or est le site top. Cette interaction permet un transfert de charge de l'imidazole vers la surface d'or, ce qui affecte la capture du CO2 (environ 50% plus faible par rapport à l'interaction Im(seule) - CO2). Mais l'augmentation du nombre de molécules d'imidazole à la surface de la couche d'or pourrait permettre une liaison plus forte entre le CO2 et l'imidazole