Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-23T20:34:24Z No. of bitstreams: 1 ALYSON SILVESTRE SANTIAGO – DISSERTAÇÃO (PPGEQ) 2014.pdf: 1626315 bytes, checksum: a4f283a010ca8f77bb130e704407b33c (MD5) / Made available in DSpace on 2018-04-23T20:34:24Z (GMT). No. of bitstreams: 1 ALYSON SILVESTRE SANTIAGO – DISSERTAÇÃO (PPGEQ) 2014.pdf: 1626315 bytes, checksum: a4f283a010ca8f77bb130e704407b33c (MD5) Previous issue date: 2014-12-18 / A produção de biocombustíveis no Brasil tem atingido patamares elevados, levando o país a ganhar destaque em nível mundial, no que se refere à produção e desenvolvimento de energias renováveis, incluindo definitivamente os biocombustíveis na matriz energética do país. Este trabalho tem como objetivo avaliar a peneira molecular CTA+-MCM-41 na reação de transesterificação do óleo de soja através da rota metílica, utilizando catálise heterogênea para produzir o biodiesel, além de avaliar a dispersão do óxido de magnésio na superfície deste catalisador. A peneira molecular CTA+-MCM-41 é obtida por um processo térmico a 60 °C por 24h utilizando o brometo de cetiltrimetilamônio, o hidróxido de tetrametilamônio, etanol e água deionizada. Para a síntese do gel que deu origem à peneira molecular, foi utilizada a seguinte composição molar: 1TEOS:0,3 CTABr:11NH3:144H2O:40ETOH. O biodiesel foi obtido a partir da reação de transesterificação do óleo de soja por rota metílica, cujas condições de operação seguiram um planejamento experimental 2² com três repetições no ponto central, onde os fatores estudados foram os efeitos das variáveis temperatura e tempo de reação. Para a caracterização dos materiais obtidos, utilizou-se uma combinação de técnicas de Difração de Raios-X e Microscopia Eletrônica de Varredura. Através do DRX pode-se observar a presença dos picos característicos da peneira molecular antes e após os processos de impregnação do metal e sua respectiva calcinação, que comprovaram o não ordenamento do material a longas distâncias no eixo dos canais mesoposoros analisados. Na reação de transesterifição sem a presença do catalisador, obteve-se conversões máximas de 84,1%, tendo sua performance melhorada na presença do CTA+-MCM-41 chegando a conversões próximas a 100%. Diante dos resultados obtidos concluiu-se que os catalisadores sintetizados têm grande potencial na produção de biodiesel. / The production of biofuels in Brazil aims to increase the productivity and development of renewable energy, including biofuels in the country's energy matrix. This work aims to evaluate the molecular sieve CTA+-MCM-41 in the transesterification reaction of soybean oil through the methyl route by using heterogeneous catalysis to produce biodiesel and also to evaluate the dispersion of magnesium oxide on the surface of this catalyst. The molecular sieve CTA+-MCM-41 is obtained by a thermal process at 60 °C for 24 hours, using cetyltrimethylammonium bromide, tetramethylammonium hydroxide, ethanol and deionized water. For synthesize the gel which results in the molecular sieve, the following molar composition was used: 1TEOS:0.3CTABr:11NH3:144H2O:40ETOH. Biodiesel has been obtained by the transesterification reaction of soybean oil through the methyl route, whose operating conditions followed a 22 experimental design with three replicates in the center point, where the investigated factors were the effects of temperature and reaction time variables. For characterization of the obtained materials, a combination of X-Ray Diffraction and Scanning Electron Microscopy techniques was used. Through the XRD, it is possible to observe the presence of the characteristic peaks of the molecular sieve before and after the processes of impregnation of the metal and its respective calcination, which prove the non-ordering of the material at long distances in the axis of the analyzed mesophores channels. At the absence of the catalyst, the conversions were up to 84.1%, with a performance increasing at the presence of the CTA+-MCM-41, reaching values close 100%. Based on the results obtained it was concluded that the synthesized catalysts have a great potential for use in the production of biodiesel.

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Polyrotaxanes consisting of 30-60 membered aliphatic crown ether macrocycles whose cavities are pierced by polysebacate chains were synthesized by several polymerization approaches including transesterification polymerization, the acid chloride method, and interfacial polymerization. The polyrotaxanes were purified by multiple reprecipitations into good solvents for the crown ethers. In some cases the threaded macrocycles are constrained onto polymer chains by the incorporation of monofunctional blocking groups at polymer chain ends, or by the copolymerization of a difunctional blocking group with other monomers. The compositions and the physical properties of the polyrotaxanes were determined by a variety of characterization techniques including NMR, UV, VPO, GPC, DSC, TGA, and intrinsic viscosity measurements. Significant amounts, up to 51 mass %, of the macrocyclic components were incorporated. Because of incorporation of flexible and polar macrocycles, polyrotaxanes display special behavior in solution and in the solid state. In solution the linear components of polyrotaxanes are stiffened by the threaded macrocycles, resulting in increased hydrodynamic volumes. The solubilities of linear polymers in polar solvents are enhanced by the incorporated crown ethers. The glass transitions are also affected by the crown ether component. Due to the movement of the macrocycles along the backbone, the macrocycles are able to aggregate and crystallize without dethreading from the polysebacate backbones. The threading and dethreading processes were systematically studied in the diol/diacid chloride system. Due to the hydrogen bonding between the cyclic and linear species, the macrocycle contents of unblocked polyrotaxanes are significantly affected by the feed ratio of macrocycle to linear monomers up to a value of 2 but are independent of reaction time and the length of diol monomers. The macrocycle content of polyrotaxanes increases non-linearly with the size of the macrocycles, presumably due to changes in the fraction of threadable conformations of the macrocycles. Although some macrocycles near the unblocked polymer chain ends are apparently susceptible to the dethreading from polymer chains, most of the macrocycles are prevented on resonable time scales, e.g., months in solution, from the dethreading by the entanglement of cyclic and linear species. / Ph. D.

Microalgae have been so far identified as the major producers of organic matter through their photosynthetic activities. In the present work, Nannochloris sp. and Amphora sp., two marine microalgae, have been investigated for proteins and lipids production. Protein fraction was quantified using Bicinchoninic acid (BCA) assay. Protein content in Nannochloris sp. was 16.69 ±4.07 % of dry mass and in Amphora sp. it was 39.89 ±2.09 % of dry mass. Enzyme assays were conducted spectrophotometrically. Nannochloris sp. had malate dehydrogenase, peroxidase and catalase activities. Amphora sp. exhibited malate dehydrogenase, catalase and cytochrome C oxidase activities. These enzymes have several valuable applications in some metabolic pathways and as antioxidant nutrition additives. Besides, lipid extraction was conducted using methanol/ chloroform solvent extraction. Crude lipid extract was analyzed using gas chromatography-mass spectrometry. Lipid contents were 8.14 ±3.67 % in Nannochloris sp. and 10.48 ±1.26% on dry basis in Amphora sp., respectively. Nannochloris sp. fatty acids were composed of C16:0 and C18:0 that are valuable for biodiesel production, and É-3 C18:3, É-6 C18:2, É-6 C16:2 having great nutritional values. In Amphora sp., the fatty acids consisted of C14:0, C16:0 and C16:1 shown to be valuable for biodiesel production and É-3 C22:6 having high nutritional values. Furthermore, a single step conversion of microalgal oil to fatty acid methyl esters was carried out starting directly from lyophilized microalgae. This promising process, in situ transesterification, led to better yields of methyl esters as compared to conventional lipid extraction followed by separate transesterification. / Master of Science

Le biodiesel est un mélange d’esters mono-alkyl utilisé comme carburant alternatif au diesel. Il est obtenu par transestérification des huiles végétales ou de graisses animales par un alcool léger.L’objectif de ce travail consiste en la recherche de catalyseurs solides acides ou basiques capables de promouvoir la réaction de transestérification de l’huile de colza par l’éthanol en conditions aussi douces que celles utilisées en catalyse homogène basique. Pour cela, deux séries de solides acides et basiques ont été préparées et caractérisées par différentes techniques (ATG-ATD, DRX, Isotherme N2). Les propriétés acides et basiques de ces solides ont également été étudiées par calorimétrie et spectroscopie Infra Rouge. Des corrélations entre les activités initiales et les propriétés acides ou basiques de ces catalyseurs ont été recherchées. L’influence des principaux paramètres réactionnels a été examinée sur le catalyseur acide et le catalyseur basique, les plus actifs. Puis une étude cinétique comparative a été réalisée. Enfin la valorisation in situ du glycérol, produit secondaire de la réaction, a été considérée.Nous avons pu montrer que le sel de césium de l’acide 12-tungstophosphorique est le catalyseur acide le plus actif, dans la gamme de solides acides étudiés. Ceci s’explique par la présence de sites acides de BrØnsted forts aptes à promouvoir la réaction en conditions douces de température. Par ailleurs, il est capable de réaliser l’éthérification in situ du glycérol par l’éthanol. En catalyse basique, le nouveau catalyseur préparé, la zircone échangée au césium, est le catalyseur le plus actif parmi les bases solides étudiées. Ce catalyseur est stable dans le milieu réactionnel après élimination par lavage à chaud des espèces Cs labiles. La comparaison des deux catalyseurs montre que la catalyse basique est nettement plus rapide que la catalyse acide. L’étude cinétique permet de proposer des différences mécanistiques entre ces deux types de catalyseurs. / Biodiesel is a mixture of mono-alkyl esters used as alternative fuel. It can be obtained by transesterification of vegetable oils or animal fats with light alcohols.The objective of this work is the research of acid and basic solid catalysts able to promote the transesterification reaction of rapeseed oil with ethanol in conditions as mild as those used in homogeneous base catalysis. For this, two series of solid acids and bases were prepared and characterized by various characterization techniques (TGA-DTA, XRD, Isothermal N2). Calorimetry and Infrared Spectroscopy have also been used to characterize acid and basic properties. Correlations between initial activity and the acidic or basic properties of these catalysts have been investigated. The influence of the main reaction parameters was examined on the most active acid and basic solid. A comparative kinetic study then allowed us to propose reaction mechanisms. Finally the in situ valorisation of glycerol, a by product of the reaction, was carried out.We have shown that the cesium salt of 12-tungstophosphoric acid catalyst is the most active among the solid acids studied. This is explained by the presence of strong BrØnsted acid sites that are able to promote the reaction under mild temperature conditions. This catalyst is capable of achieving in situ etherification of glycerol with ethanol. In base catalysis, the newly prepared catalyst, zirconia exchanged with Cesium, is the most active catalyst among the solid bases studied. This catalyst is stable in the reaction medium after removal of the labile Cs species by hot washing. Comparison of the two catalysts shows that the base catalysis is much faster than acid catalysis. A kinetic comparative study allows us to propose mechanistic differences between these two types of catalysts.

Alternative fuels are becoming important due to diminishing fossil fuel reserves and the environmental hazards associated with exhaust gases. Biodiesel is an attractive alternative fuel because it is environmentally friendly and can be synthesized from edible/non-edible oils. Though several methods are available for synthesis, transesterification is the preferred route for biodiesel synthesis. The current techniques for transesterification of the oils to biodiesel are based on acid/alkali catalysis. However, these methods do not work for oils with high free fatty acid content and also require an additional downstream step for separation of catalyst from the product. In this work, we investigate the synthesis of biodiesel by two techniques: in supercritical methanol and ethanol without any catalyst; in supercritical carbon dioxide using enzyme as catalyst. In the first technique, the transesterification of refined grade edible oil like sunflower oil, palm oil and groundnut oil, and crude non-edible oils like Pongamia pinnata and Jatropha curcas was investigated in supercritical methanol and ethanol without using any catalyst from 200 oC to 400 oC at 200 bar. The variables affecting the conversion during transesterification, such as molar ratio of alcohol to oil, temperature and time were investigated in supercritical methanol and ethanol. The conversion to biodiesel increased from 30-40% at a molar ratio of 10 to 80-85% at a molar ratio of 45 to 50. Very high conversions (96-97%) were obtained in supercritical methanol and ethanol within 30 minutes at 350 oC. The kinetics of the reaction was modeled, the rate coefficients and activation energies were determined. As an enzymatic transesterification in organic solvents is mass transfer limited, supercritical fluids are found to be a better alternative because of their gas like diffusivity. Among potentially interesting solvents for enzymatic synthesis, carbon dioxide is the most obvious choice in supercritical fluids, because it is non-toxic, nonflammable and easily available. Because the products and the enzyme do not dissolve in carbon dioxide at room conditions, separation can easily be achieved by reduction of pressure Thus, the enzymatic transesterification for production of biodiesel in supercritical fluids under mild conditions is of commercial interest. Therefore, biodiesel was synthesized using immobilized enzyme (Lipase, Novozym-435) in supercritical carbon dioxide. The effect of reaction variables like temperature, molar ratio, enzyme loading and kinetics of the reaction was investigated. The conversion to biodiesel was found to be lower in supercritical carbon dioxide than that in supercritical alcohol.

M. Tech. (Department of Chemistry, Faculty of Applied And Computer Sciences), Vaal University of Technology. / Biodiesel has an ability to solve the problem associated with the use of fossil fuels as a source of energy. The aim of this study was to produce biodiesel from waste cooking oil (WCO) by transesterification, catalysed with potassium hydroxide (KOH) supported on attapulgite (ATP) clay as the heterogeneous catalyst. WCO was used on the basis that it is one of the cheapest feedstocks for biodiesel production, is readily available and can minimise environmental impact. ATP clay was first crushed and sieved to particle sizes of ≤ 90 μm and subsequently treated with hydrochloric acid (HCl) to remove impurities. The KOH supported ATP catalyst was prepared through ion exchange method by soaking ATP into KOH solution, dried in an oven and later calcined at 400 ℃ in a furnace. The prepared catalyst and ATP clay were characterised using Hammett indicator to determine the basic strength of the catalyst. XRF and EDX were used to determine the elemental composition of the catalyst whilst XRD was used to determine the crystallinity of the ATP after modification. The functional groups of ATP were determined by FTIR. BET was utilised to determine the changes on the surface area, pore volume and pore diameter of ATP and on the other hand, SEM was used to determine the morphological changes on the surface of ATP. The XRD, FTIR, BET AND SEM-EDX showed that addition of potassium caused changes on the surface of the ATP. The optimal conditions for the transesterification reaction of waste cooking oil with methanol were found to be oil-to-methanol molar ratio of 1:15, 3wt% catalyst amount, 65 ℃, 3 h of a reaction time, at 200 rpm stirring rate and 94 % biodiesel yield was obtained. After the catalyst was reuse three consecutive times, the decrease in biodiesel yield was observed (Figure 17) after each cycle. However, the 5MKOH/ATP catalyst is heterogeneous and can be used to transesterify WCO with good yield.

No / Biodiesel has turned out to be an integral part of the discussion of renewable energy sources and has diverse advantages in terms of its flexibility and applicability. Considering the characteristics of the transesterification reaction, a laboratory-scale system has been developed in this work. Waste Vegetable Oil (WVO), mainly sunflower oil, from local sources has been used and the transesterification carried out using methanol in the presence of sodium hydroxide catalyst. Characterisation of the biodiesel produced has been carried out using a number of different techniques including rheology, calorimetry, and gas liquid chromatography. The main factors affecting the % yield of biodiesel are temperature, catalyst, and alcohol to triglyceride ratio. Thus, experimental work has been carried out so as to study the rate and yield of the reaction as a function of those factors. A model has also been developed to validate the experimental data and this should help in increasing the efficiency of these processes and reducing the energy input. Moreover, the novel use of ultrasound as a method of measuring progression of the reaction is correlated with in-situ pH monitoring of the reaction process.

Visando o crescente interesse em pesquisa de novos materiais que utilizam polímeros biodegradáveis, este presente trabalho teve como objetivo a síntese de novos copolímeros através da reação de transesterificação no estado fundido entre poli(3-hidroxibutirato) (PHB), um polímero biodegradável, com poli(etileno glicol) (PEG). Sabe-se que um dos grandes problemas no uso do PHB é a sua elevada cristalinidade e instabilidade térmica, pois possui temperatura de fusão entre 170 e 180°C e apresenta degradação térmica a 190°C. A reação de transesterificação é uma alternativa para fazer a modificação química deste polímero, o que também viabiliza a formação de copolímeros anfifílicos triblocos. O objetivo final foi utilizar este novo material para o preparo de nanopartículas poliméricas a partir do método de difusão do solvente. Tais partículas são utilizadas para microencapsulamento de fármacos. Os copolímeros foram sintetizados e caracterizados por ensaio de solubilidade, espectrometria de ressonância magnética nuclear de hidrogênio (RMN), calorimetria diferencial exploratória (DSC), espectroscopia no infravermelho com transformada de Fourier (FTIR), cromatografia de permeação em gel (GPC), análise por difração de Raios-X (WAXS), microscopia ótica de luz polarizada (MOLP) e microscopia eletrônica de varredura (MEV). A indicação de formação de copolímero anfifílico pode ser observada nos ensaios de solubilidade, pois o copolímero mostrou-se parcialmente solúvel em uma série de solventes em que o PHB original é insolúvel. A modificação química pode ser observada com as técnicas de RMN e FTIR, cujos espectros apresentaram absorções referentes ao grupo carbonila da ligação éster. As técnicas de DSC, WAXS e MOLP mostraram uma ligeira redução na cristalinidade do material, além da temperatura de fusão reduzir-se de 171ºC para 154°C. Com o GPC observou-se uma redução da massa molar, o que facilita a formação das nanopartículas poliméricas. As nanopartículas apresentaram tamanhos com diâmetros ao redor de 250nm, quando observadas por MEV. / Aimed at the growing interest in research on new materials using biodegradable polymers, the present work was aimed at the synthesis of new copolymers through transesterification reaction in the molten state of poly (3-hydroxybutyrate) (PHB), a biodegradable polymer, poly (ethylene glycol) (PEG). It is well known that a major problem in the use of PHB is its high crystallinity and thermal instability, as it has melting temperature between 170 and 180° C and shows thermal degradation at 190°C. The transesterification reaction is an alternative to the chemical modification of this polymer, which also enables the formation of amphiphilic triblock copolymers. The mainly goal of this studies was to use this new material for the preparation of polymeric nanoparticles from the solvent diffusion method. Such particles are used for microencapsulation of drugs. The copolymers were synthesized and characterized by solubility test, Nuclear Magnetic Resonance Spectroscopy of Hydrogen (NMR), Differential Scanning Calorimetry (DSC), Infrared Spectroscopy with Fourier transform (FTIR), Gel permeation chromatography (GPC) analysis by X-ray diffraction (WAXS), polarized light optical microscopy (MOLP) and scanning electron microscopy (SEM). The signs of the formation of amphiphilic copolymer can be observed in the trials of solubility, since the copolymer was found to be partially soluble in a variety of solvents in the original PHB is insoluble. The chemical modification can be observed with the techniques of NMR and FTIR spectra which showed absorptions for the carbonyl group of the ester linkage. The techniques of DSC, WAXS and MOLP showed a decrease in crystallinity of the material in 15%, and reduce the melting temperature is 171ºC to 154°C. With the GPC showed a reduction in molar mass, which facilitates the formation of polymeric nanoparticles. The nanoparticles showed sizes with diameters around 250nm observed by SEM.