Ce travail étudie les matériaux composites zéolithes surfactifs, principes actifs pour des applications pharmaceutiques. D'abord sont identifiées les principales propriétés physiques, chimiques et biologiques des matériaux, requises pour des applications en tant que supports médicamenteux ciblant certaines formes de cancer. Par la suite sont décrits les différentes étapes de formulation des supports médicamenteux à base des zéolithes naturelles, les caractéristiques des matériaux intermédiaires ainsi obtenus, ainsi que les mécanismes des phénomènes interfaciaux à l'origine de l'action de ces matériaux. La dernière partie est consacrée à l'étude d'un relargage contrôlé des principes actifs de l'interface jusque dans un milieu aqueux modèle. / This work studies the composite zeolites surfactants, active principles for pharmaceutical applications. First identified the main physical, chemical and biological materials, required for applications as drug carriers targeting some cancers. Subsequently described the various stages of formulation of drug carriers based on natural zeolites, the characteristics of intermediate materials obtained, and the mechanisms of interfacial phenomena at the origin of the action of these materials. The last part is devoted to the study of controlled release of active ingredients of the interface into a model aqueous medium.

This thesis explains a method based on the homogenisation of zeta potential charges on carbon supports for the production of hierarchical structured zeolitic composites. The modification of carbons’ surface chemistry allowed zeolite particles to be fixed to the support by electrostatic interactions. In order to achieve this, the size reduction of zeolite particles was carried out by two different methods: a) ball milling and b) a synthetic route to produce zeolite colloidal dispersions. Also, the seeding method, based on hydrothermal growth was compared. The prepared materials in this work were designed to be used in the sorption of cations, and to allow vitrification and thereby reduce the final adsorbent volume. Results showed that a large pollutant amount can be trapped using a lower volume of material reducing costs and final waste disposal. The zeolites used in this work were selected based on their low density framework and low Si/Al ratio. Synthetic zeolites A, Y and clinoptilolite were successfully produced. Natural clinoptilolite was also utilised in this work. Also, zeolite A was produced at nanometre scale following the clear solutions method. All materials were successfully incorporated onto supports to produce multimodal porosity materials. The hierarchical modification of natural clinoptilolite, following a straightforward and nonexpensive methodology, is one the most significant contributions of this work. Carbons are used as supports due to their high surface area, they can be obtained from low-cost sources such as agroindustrial wastes and carbons allow volume reduction if materials are vitrified at high temperatures. In this work, carbons were produced from corn cob and husk, sugar cane bagasse, cherry stones, date stones and hazelnut shells. The prepared composite materials were tested in the removal of toxic ions from water solutions: cobalt, copper and caesium ions were effectively removed from aqueous media. Adsorption experiments showed that the distribution of supported zeolite particles improved their uptake efficiency and capacity. The kinetic studies revealed an enhanced rate constant for carbon-zeolites composites in comparison with pure zeolites. Diffusivity results suggested that mass transfer characteristics are modified by using hierarchical porous materials; results showed that particle size or support nature can modify diffusion resistances, reducing intraparticle diffusion and accelerating the overall kinetic processes. Adsorption equilibrium data was correlated using Langmuir and Freundlich models.

Orientador: Francisco Maugeri Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T01:27:34Z (GMT). No. of bitstreams: 1 Santos_TihanyMoritaAnterodos_D.pdf: 818442 bytes, checksum: c034c03d154eadb3c1ed625f0144e680 (MD5) Previous issue date: 2004 / Resumo: O xilitol é um açúcar-álcool com ampla utilização na indústria alimentícia, porém mesmo sendo numerosos os estudos sobre a sua produção a partir da fermentação de hidrolisados hemicelulósicos, poucos são os trabalhos que tratam da sua separação e purificação. O objetivo principal deste trabalho é, portanto, desenvolver uma metodologia de separação do xilitol dos compostos remanescentes no meio fermentado obtido por fermentação do hidrolisado de bagaço de cana-de-açúcar por Candida guilliermondii. Inicialmente, ensaios conduzidos com as zeólitas Na86X, Baylith 415 e Baylith WE 894 em diferentes formas catiônicas permitiram constatar a maior eficácia das zeólitas NaWE e BaWE na adsorção do xilitol e posteriormente, o uso de colunas de leito fixo empacotadas com estas duas zeólitas em diferentes granulometrias, a 30 e 50 ºC, revelou que a separação do xilitol foi superior com o uso da zeólita BaWE com partículas de 53-125 µm a 50 ºC. Estas condições foram empregadas na determinação da constante de equilíbrio deste composto usando a resposta a pulsos cromatográficos, sendo o valor obtido igual a 1,03. Os efeitos da temperatura, da velocidade superficial e da razão volume de pulso/volume de leito (Vp/Vl) sobre a separação do xilitol foram investigados através de análise estatística de experimentos delineados por um planejamento fatorial 23, que revelou que a condição mais favorável para separar o xilitol envolve o uso de temperatura de 80 ºC, velocidade superficial de 0,5 cm.min-1 e Vp/Vl igual a 0,2. O emprego de etanol e acetona em diferentes concentrações como eluentes permitiu concluir, após avaliação das eficiências obtidas e do custo dos mesmos, que o etanol a 30 % é o eluente mais adequado para ser utilizado na separação do xilitol. Após a determinação dos parâmetros de separação em meio sintético, iniciaram-se os testes com meio fermentado, obtido da fermentação de hidrolisado de bagaço de cana-de-açúcar com Candida guilliermondii. Dentre as metodologias empregadas na destoxificação deste meio, o uso de resinas de troca iônica foi o mais eficiente, permitindo obter maiores parâmetros fermentativos. A avaliação da separação do xilitol obtido por fermentação foi realizada variando-se o número de colunas e o volume do pulso e os melhores resultados foram obtidos utilizando-se 2 e 3 colunas de zeólita BaWE alimentadas com volume de pulso igual a 8 % do volume do leito. Apesar das eficiências de separação terem sido superiores com 3 colunas, verificou-se que a porcentagem de xilitol nas frações enriquecidas e a quantidade recuperada deste poliol foram somente ligeiramente superiores às obtidas em sistema com 2 colunas (0,5 e 2,1 % superiores, respectivamente). Além deste fato, o sistema de 2 colunas contribuiu para uma eluição mais rápida dos compostos e requereu menor volume de eluente. Estas observações permitiram concluir que dentre os sistemas experimentais avaliados, o composto por 2 colunas de zeólita BaWE com altura total de leito de 89 cm, alimentadas com volume de pulso igual a 8 % do volume do leito, a 80 ºC e 0,5 cm.min-1 conduziu a uma melhor separação do xilitol. Nestas condições obteve-se uma fração com 97,28 % de xilitol, 0,84 % de arabinose, 0,82 % de xilose e 0,54 % de arabitol e eficiências de separação de 3,17 e 2,72 com relação a arabinose e a xilose, respectivamente / Abstract: Xylitol is a sugar alcohol with large utilization in food industry. Nevertheless, although there are numerous studies on its production from the fermentation of hemicellulosic hydrolysates, there are few works dealing with its separation and purification. The principal aim of this work is, therefore, to develop a methodology for xylitol separation from the compounds remaining in the fermented medium, which was obtained by fermentation with Candida guilliermondii in sugar cane bagasse hydrolysate. Initially, assays were conducted with the zeolites Na86X, Baylith 415 and Baylith WE 894 in different cationic forms, which permitted us to observe a higher effectiveness of zeolites NaWE and BaWE in the xylitol adsorption, and later, the use of fixed bed columns packed with these two zeolites in different granulometries, at 30 and 50 ºC, revealed that the xylitol separation was better when 53-125 µm BaWE zeolite particles at 50 ºC were utilized. These conditions were also employed for determining the equilibrium constant of this compound using the chromatographic pulse response technique, the value obtained being equal to 1.03. The effects of temperature, superficial velocity and pulse volume/bed volume ratio (Vp/Vl) on the xylitol separation were investigated by means of statistical analysis of experiments described by a 23 factorial design, which showed that the most favorable conditions for this separation are: temperature of 80 ºC, superficial velocity of 0.5 cm.min-1 and Vp/Vl of 0.2. The use of ethanol and acetone at different concentrations as eluents enabled us to conclude, after an evaluation of their costs and of the efficiencies obtained, that ethanol at 30 % is the most suitable eluent for xylitol separation. After determining the parameters of separation in synthetic medium, tests were performed with fermented medium obtained from fermentation of sugar cane bagasse hydrolysate with Candida guilliermondii. Of the methodologies employed for detoxification of this medium, the use of ion-exchange resins proved the most effective, giving higher fermentative parameters. The separation of xylitol obtained from fermentation was evaluated by varying the number of columns and the pulse volume, the best results being attained with 2 and 3 columns of zeolite BaWE fed with a pulse volume equal to 8 % of bed volume. Although the separation efficiencies were enhanced by using 3 columns, it was observed that the amount of xylitol in the enriched fractions and its recovered amount were only slightly higher than those obtained using 2 columns (0.5 and 2.1 % higher, respectively). In addition, the 2-column system contributed to a more rapid elution of the compounds and required a lower eluent volume. It can therefore be concluded that, of the experimental systems that were evaluated, the one composed of two columns of zeolite BaWE with a bed 89 cm in total height and fed with a pulse volume equal to 8 % of bed volume, at 80 ºC and 0.5cm.min-1, led to a better xylitol separation. Under these conditions, the fraction obtained contained 97.28 % xylitol, 0.84 % arabinose, 0.82 % xylose and 0.54 % arabitol, and the efficiencies of xylitol separation from arabinose and xylose were 3.17 and 2.72 respectively / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Orientadores: Munir Salomão Skaf, Vitor Rafael Coluci / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-18T13:27:57Z (GMT). No. of bitstreams: 1 Faro_TatianaMellodaCosta_M.pdf: 2906176 bytes, checksum: c28c56bc08c5c23e3a6f8668b1148162 (MD5) Previous issue date: 2011 / Resumo: Zeólitos são aluminossilicatos cuja estrutura consiste em tetraedros TO4 (com T=Si,Al) que compartilham todos os seus vértices com os tetraedros vizinhos, formando uma rede tridimensional altamente porosa e de baixa densidade. A substituição de Si por Al na matriz zeolítica leva à formação de uma carga total negativa, contrabalanceada pela presença de cátions trocáveis no material. Os zeólitos são objetos de estudo importantes por serem muito usados na indústria como peneiras moleculares, trocadores iônicos e catalisadores. A localização dos cátions trocáveis nos sítios cristalográficos de um zeólito e a identidade desses cátions são fatores que governam a adsorção de gases e outras moléculas pequenas no zeólito e o comportamento catalítico dos zeólitos. Embora várias técnicas experimentais sejam usadas para caracterizar tais cátions, é comum ocorrerem situações nas quais alguns dos cátions trocáveis não conseguem ser localizados com exatidão pelos métodos experimentais; nesses casos, estudos computacionais por simulações de Dinâmica Molecular (DM) são bastante úteis para ajudar a elucidar o posicionamento dos cátions trocáveis na estrutura zeolítica e as suas respectivas mobilidades. Neste trabalho, realizamos simulações de Dinâmica Molecular dos zeólitos NaX e BaX na aproximação da matriz rígida e considerando a vibração dos átomos da matriz com o objetivo de analisar a influência da vibração da matriz zeolítica na determinação de diversas propriedades do sistema, como o posicionamento dos cátions trocáveis e o espectro de absorção desses cátions na região do infravermelho longínquo. O zeólito NaX foi escolhido por ser o precursor de quase todos os outros zeólitos do tipo X, havendo assim muitos estudos experimentais sobre ele na literatura; já o zeólito BaX é importante pois as faujasitas de bário são usadas na indústria em processos de separação de moléculas aromáticas, como os xilenos / Abstract: Zeolites are aluminosilicates whose structure consists of TO4 tetrahedra (with T=Si,Al) that share all its corners with the neighboring tetrahedra, thus forming a three-dimensional network highly porous and with a low density. The substitution of Si with Al in the zeolitic matrix leads to the generation of a net negative charge, balanced by the presence of exchangeable cations in the material. Zeolites are important objects of study because they are used industrially as molecular sieves, ion exchangers and catalysts. The location the exchangeable cations in the zeolite crystallographic sites and the identity of these cations are factors that govern the adsorption of gases and other small molecules in the zeolite and the catalytic behavior of the zeolite. Although many experimental techniques are used to characterize those cations, there are situations in which some of the exchangeable cations can not be located accurately by experimental methods; in these cases, computational studies by Molecular Dynamics (MD) simulations are very useful to help elucidate the location of the exchangeable cations in the zeolitic structure and its respective mobilities. In this work, we carried out molecular dynamics simulations of the zeolites NaX and BaX in the rigid matrix approximation and considering the vibration of the matrix atoms with the intention to analyze the influence of the vibration of the zeolitic matrix in the determination of several properties of the system, such as the location of the exchangeable cations and the absorption spectra of these cations in the far infrared region. Zeolite NaX was chosen because it is the precursor of almost all other type-X zeolites, so there are many experimental studies about it in the literature; zeolite BaX is important because barium faujasites are used in the industry in the separation process of aromatic molecules, such as xylenes / Mestrado / Físico-Química / Mestre em Química

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering September, 2017 / South Africa emits large amounts of carbon dioxide (CO2) due to its reliance on coal. The emission of CO2 needs to be reduced for clean sustainable energy generation. Research efforts have therefore been devoted to reducing CO2 emissions by developing cost-effective methods for capturing and storing it. Amine-based absorption using monoethanolamine solvent is the most mature technique for CO2 capture despite its huge energy consumption, corrosiveness and difficulty in solvent regeneration. However, CO2 removal by solid adsorbents is a promising alternative because it consumes less energy, and can be operated at moderate temperature and pressure. Metal organic frameworks have received attention as a CO2 adsorbent because they have large surface areas, open metal sites, high porosity and they require less energy for regeneration. This research was aimed at optimizing and scaling-up SOD-ZMOF through structural modification for enhanced CO2 adsorption by impregnating it with chitosan. Scaled-up SOD-ZMOF samples were prepared as described elsewhere and impregnated with Chitosan. Physiochemical properties obtained using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Nitrogen physisorption showed that SOD-ZMOF and SOD-ZMOF-chitosan were successfully synthesized. Qualitatively, the surface area of the SOD-ZMOF synthesized using the scaled up protocol is lower than the one prepared using the non-scaled-up protocol XRD pattern of SOD-ZMOF showed that it was crystalline and was in agreement with literature. The XRD peaks of the SOD-ZMOF decreased after chitosan impregnation showing that chitosan was impregnated on SOD-ZMOF. The FTIR spectrum of SOD-ZMOF showed functional groups present in organic linker used to synthesize SOD-ZMOF, and that of the SOD-ZMOF-chitosan revealed the same functional groups but with disappearance of carboxylic acid functional group. N2 physisorption showed a decrease in BET surface area and pore volume after chitosan impregnation on SOD-ZMOF as well. Performance evaluation of the material was carried out with a demonstration adsorption set-up using a 15%/85% CO2/N2 mixture and as a thermal gravimetric analysis (TGA) using 100% CO2. For both the packed-bed column and the TGA experiments, evaluation was conducted on SOD-ZMOF and SOD-ZMOF with chitosan for comparison. About 50 mg of the adsorbent was used at 25 oC, 1 bar and 25 ml/min for the packed-bed column. For the adsorption with the TGA, 11 mg of adsorbent was used at 25 ℃, 1 bar and 60 ml/min. SOD-ZMOF showed improved adsorption capacity after chitosan impregnation. CO2 adsorption capacity of SOD-ZMOF increased by 16% and 39% using packed-bed column and TGA, respectively, after chitosan impregnation. The increase in adsorption capacity was attributed to the impregnated chitosan that has amine groups that display a high affinity for CO2. A traditional approach was used to investigate the effect of adsorption temperature and inlet gas flowrate on the CO2 adsorption capacity of SOD-ZMOF-chitosan. This was done using both the parked bed column and the TGA. Temperature range of 25-80 ℃ and inlet gas flowrate range of 25-90 ml/min were investigated. Adsorption capacity increased with a decrease in temperature and inlet gas flowrate. For the packed-bed column, maximum of 781 mg CO2/ g adsorbent was obtained at 25℃, 1 bar, 25 ml/min and for the TGA a maximum CO2 adsorption capacity of 23 mg/ g adsorbent at 25 ℃, 1 bar, and 60 ml/min was obtained. / MT2018

Zeolites with encapsulated metal nanoparticles have attracted a wide attention in heterogeneous catalysis due to their high catalytic activity, selectivity, and stability. The PhD thesis was focused on design and synthesis of metal@zeolite catalysts with small and uniformly distributed metal nanoparticles. The main interests were encapsulation of metal nanoparticles into zeolites by co-crystallization strategy and 2-dimensional to 3-dimensional zeolite transformation approach. The PhD work was performed at the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry and Department of Physical and Macromolecular Chemistry, Faculty of Science at Charles University under the supervision of Prof. Jiří Čejka. Zeolites are inorganic crystalline aluminosilicates with microporous framework structures. The micropores of zeolites provide the ideal microenvironment to accommodate metal nanoparticles. During metal nanoparticles formation in zeolite micropores, they can be limited by a rigid framework, preventing the aggregation and leaching of metal during the reaction process. Furthermore, the diameters of zeolite micropores are usually in the range of 0.3-1.5 nm, which can be used to discriminate molecules depending on their size and shape, thus endowing the metal@zeolite...

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Diffusion is an omnipresent, most fundamental phenomenon in nature and thus critical for the performance of numerous technologies. This is in particular true for nanoporous materials with manifold applications for matter upgrading by separation, purification and conversion. The path lengths of molecular transportation within the industrial plants range from the elementary steps of diffusion within the micropores of the individual particles up to the matter flow over macroscopic distances. Each of them might be decisive in determining overall performance so that detailed knowledge of all modes of mass transfer is crucial for a knowledge-based optimization of the devices with reference to their transport properties. The rate of mass transfer is particularly complicated to be assessed within the individual (adsorbent) particles/crystallites with pore sizes of the order of molecular dimensions. We are going to present two powerful techniques exactly for this application, operating under both equilibrium (Pulsed Field Gradient (PFG) NMR) and non-equilibrium (Microimaging by interference microscopy and IR microscopy) conditions. The potentials of these techniques are demonstrated in a few showcases, notably including the options of transport enhancement in pore hierarchies. The contribution concludes with a survey on present activities within an IUPAC initiative aiming at the elaboration of “guidelines for measurements and reporting of diffusion properties of chemical compounds in nanoporous materials”.

A vapor phase impregnation technique with Pt(acac)₂ has been developed and used to load Pt into aluminosilicate (KL, BaKL, KBaKL, NaY, CsNaY, FAU, EMT, ZSM-12 and SSZ-24) and aluminophosphate (AIP0₄-5 and VPI-5) molecular sieves. ¹³C MAS NMR, TEM and H₂ chemisorption measurements reveal that Pt can be loaded into the micropores of molecular sieves with both charged and neutral frameworks. Pt containing molecular sieves were tested as catalysts for the aromatization of n-hexane at 460 - 510°C and atmospheric total pressure in order to study the influence of Pt cluster size and support acidity/basicity, microstructure and chemical composition on activity and selectivity. High selectivity to benzene over most of the zeolite samples demonstrates that support acidity/basicity and microstructure do not contribute directly to the aromatization selectivity over Pt catalysts. A clear trend of increasing benzene selectivity with decreasing Pt cluster size is found. These observations suggest that the exceptional reactivity of Pt/KL for the aromatization of n-hexane results from the lack of any acidity in the support and the ability of zeolite L to stabilize the formation of extremely small Pt clusters. Pt/AIP0₄-5 and Pt/VPI-5 show high selectivity to n-hexane with little formation of benzene while opposite is observed for Pt/SSZ-24. The differences in catalytic behavior are attributed to variations in the environment of Pt clusters which are situated in either an aluminophosphate or silicate micropore. See document for rest of abstract. / Ph. D.