Produção de biodiesel a partir de pastas de gordura e resíduo de glicerol

O principal objectivo deste trabalho consistiu na produção de biodiesel a partir de resíduos fornecidos pela Empresa SOCIPOLE, S.A. Esta, forneceu, pastas de gordura (depósito formado nos óleos usados), só aproveitadas pela empresa para a produção de sabões, e resíduo de glicerol proveniente da produção de biodiesel. Com as pastas de gordura, foi feito um estudo onde se variaram alguns parâmetros, tais como: o tipo de reactor, catalisador, temperatura, agitação, tempo de reacção, razão molar gordura:metanol e condições de secagem. O estudo mais pormenorizado foi efectuado com o NaOH, como catalisador. Foram feitos vários ensaios para os tempos de reacção de 30minutos, 1hora e 2horas, a 65ºC e razão molar gordura:metanol 1:6, tendo-se obtido respectivamente 86,7; 88,1 e 87,5% para o teor de ésteres. No caso da resina catiónica forte como catalisador, aparentemente não houve reacção ao fim de 12h, enquanto no ensaio que utilizou o ácido sulfúrico, o teor de ésteres foi de 82,6%, ao fim de 12h com razão molar gordura:metanol igual a 1:11. Quanto à produção de biodiesel a partir do resíduo de ácidos gordos resultante da purificação do resíduo de glicerol, foi feito um estudo preliminar usando diferentes catalisadores, uma resina catiónica forte, ácido sulfúrico e zircónia sulfatada. Este resíduo continha cerca de 60% de ácidos gordos e aproximadamente 39% de ésteres metílicos. Dos três catalisadores usados, o que permitiu obter maior teor de ésteres foi a zircónia sulfatada, tendo-se obtido 82,9% trabalhando a 60ºC durante 18horas com agitação de 230rpm e razão molar ácidos gordos:metanol de 1:12 . O ensaio em que se obteve menor percentagem de ésteres (56,4%) foi com resina catiónica. Com as duas matérias-primas obteve-se sempre um teor de ésteres, no produto final, abaixo dos 96,5% estabelecidos pela Norma Europeia EN 14103. Estes resultados reflectem provavelmente a composição complexa das matérias-primas. As pastas de gordura podem conter compostos não esterificáveis, solúveis no biodiesel, ou mais dificilmente esterificáveis nas condições operacionais usadas. Já o resíduo de ácidos gordos apresenta uma cor escura o que indica a existência de compostos corados, talvez polímeros. Portanto, para se tirar conclusões fundamentadas é necessário fazer análises mais completas das pastas de gordura e do resíduo de ácidos gordos, assim como ao biodiesel produzido de forma a identificar as possíveis contaminações existentes nos produtos com esta proveniência.

Synthesis and characterization of sugar containing hydrophilic and hydrophobic polymers with potential application in medicine

Dissertation toobtaina Master of Science degree in Bioorganics

Staging the Scientist: The Representation of Science and its Processes in American and British Drama

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Estudos Ingleses e Norte Americanos

Development of novel ionic liquids based on biological molecules

Ionic Liquids (ILs) belong to a class of compounds with unusual properties: very low vapour pressure; high chemical and thermal stability and the ability to dissolve a wide range of substances. A new field in research is evaluating the possibility to use natural chiral biomolecules for the preparation of chiral ionic liquids (CILs). This important challenge in synthetic chemistry can open new avenues of research in order to avoid some problems related with the intrinsic biodegradability and toxicity associated to conventional ILs. The research work developed aimed for the synthesis of CILs, their characterization and possible applications, based on biological moieties used either as chiral cations or anions, depending on the synthetic manipulation of the derivatives. Overall, a total of 28 organic salts, including CILs were synthesized: 9 based on L-cysteine derivatives, 12 based on L-proline, 3 based on nucleosides and 4 based on nucleotides. All these new CILs were completely characterized and their chemical and physical properties were evaluated. Some CILs based on L-cysteine have been applied for discrimination processes, including resolution of racemates and as a chiral catalyst for asymmetric Aldol condensation. L-proline derived CILs were also studied as chiral catalysts for Michael reaction. In parallel, the interactions of macrocyclic oligosugars called cyclodextrins (CDs) with several ILs were studied. It was possible to improve the solubility of CDs in water and serum. Additionally, fatty acids and steroids showed an increase in water solubility when ILs-CDs systems were used. The development of efficient and selective ILs-CDs systems is indispensable to expand the range of their applications in host-guest interactions, drug delivery systems or catalytic reactions. Novel salts derived from nucleobases were used in order to enhance the fluorescence in aqueous solution. Additionally, preliminary studies regarding ethyl lactate as an alternative solvent for asymmetric organocatalysis were performed.

Bioremediation and CO2 scavenging using molybdenum-containing enzymes

Carbon dioxide valorization, will not only help to relieve the greenhouse effect but might also allow us to transform it in value-added chemicals that will help overcoming the energy crisis. To accomplish this goal, more research that focus on sequestering CO2 and endeavors through a carbon-neutral or carbon-negative strategy is needed in order to handle with the dwindling fossil fuel supplies and their environmental impact. Formate dehydrogenases are a promising means of turning CO2 into a biofuel that will allow for a reduction of greenhouse gas emissions and for a significant change to the economic paramount. The main objective of this work was to assess whether a NAD+-independent molybdenum-containing formate dehydrogenase is able to catalyze the reduction of CO2 to formate. To achieve this, a molybdenum-containing formate dehydrogenase was isolated from the sulfate reducing bacteria Desulfovibrio desulfuricans ATCC 27774. Growth conditions were found that allowed for a greater cellular mass recovery and formate dehydrogenase expression. After growth trials, kinetic assays for formate oxidation and CO2 reduction were performed and kinetic parameters determined. For the formate oxidation reaction, a KM of 49 μM and a turnover constant of 146 s-1 were determined. These kinetic parameters are in agreement with those determined by Mota, et al. (2011). Finally, we found that this molybdenum-containing enzyme was able to catalyze the reduction of CO2 to formate with a turnover constant of 4.6 s-1 and a KM of 13 μM. For the first time a NAD+-independent molybdenum-containing formate dehydrogenase was found to catalyze CO2 reduction, allowing its use as a biocatalyst in energetically efficient CO2 fixation processes that can be directed towards bioremediation or as an alternative and renewable energy source. Characterizing these enzymes may lead to the development of more efficient synthetic catalysts, make them readily available and more suited for practical applications.

The thermal effects on the methanol-to-olefins reaction: A modelling and experimental approach

With the projection of an increasing world population, hand-in-hand with a journey towards a bigger number of developed countries, further demand on basic chemical building blocks, as ethylene and propylene, has to be properly addressed in the next decades. The methanol-to-olefins (MTO) is an interesting reaction to produce those alkenes using coal, gas or alternative sources, like biomass, through syngas as a source for the production of methanol. This technology has been widely applied since 1985 and most of the processes are making use of zeolites as catalysts, particularly ZSM-5. Although its selectivity is not especially biased over light olefins, it resists to a quick deactivation by coke deposition, making it quite attractive when it comes to industrial environments; nevertheless, this is a highly exothermic reaction, which is hard to control and to anticipate problems, such as temperature runaways or hot-spots, inside the catalytic bed. The main focus of this project is to study those temperature effects, by addressing both experimental, where the catalytic performance and the temperature profiles are studied, and modelling fronts, which consists in a five step strategy to predict the weight fractions and activity. The mind-set of catalytic testing is present in all the developed assays. It was verified that the selectivity towards light olefins increases with temperature, although this also leads to a much faster catalyst deactivation. To oppose this effect, experiments were carried using a diluted bed, having been able to increase the catalyst lifetime between 32% and 47%. Additionally, experiments with three thermocouples placed inside the catalytic bed were performed, analysing the deactivation wave and the peaks of temperature throughout the bed. Regeneration was done between consecutive runs and it was concluded that this action can be a powerful means to increase the catalyst lifetime, maintaining a constant selectivity towards light olefins, by losing acid strength in a steam stabilised zeolitic structure. On the other hand, developments on the other approach lead to the construction of a raw basic model, able to predict weight fractions, that should be tuned to be a tool for deactivation and temperature profiles prediction.

A technical investigation of an oil painting on copper support, including a study on consolidants for treatment

Paper submitted to e-conservation Journal: Maria Leonor Oliveira, Leslie Carlyle, Sara Fragoso, Isabel Pombo Cardoso and João Coroado, “Investigations into paint delamination and consolidation of an oil painting on copper support”.

Electrosynthesis of heterocyclic compounds by radical cyclization in environmentally friendly media

We investigated the reductive intramolecular cyclization of bromopropargyl ethers derivatives, catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane)nickel(I), [Ni(tmc)]+ as the catalysts in N,N,N-trimethyl-N-(2- hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide,[N1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim][NTf2] by cyclic voltammetry and controlled-potential electrolysis. The results show that the reaction leads to the formation of the expected cyclic compounds, which are important intermediates in the synthesis of natural products with possible biological activities.

Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.

Aproximación al diseño de sistemas de bio-reactores para la delignificación de materiales lignocelulósicos y para la decontaminación de suelos y efluentes. Approximation to the design of bio-reactors systems for the delignificación of lignocellulosic materials and for the decontamination of soil and effluents

Los materiales lignocelulósicos residuales de las actividades agroindustriales pueden ser aprovechados como fuente de lignina, hemicelulosa y celulosa. El tratamiento químico del material lignocelulósico se debe enfrentar al hecho de que dicho material es bastante recalcitrante a tal ataque, fundamentalmente debido a la presencia del polímero lignina. Esto se puede lograr también utilizando hongos de la podredumbre blanca de la madera. Estos producen enzimas lignolíticas extracelulares fundamentalmente Lacasa, que oxida la lignina a CO2. Tambien oxida un amplio rango de sustratos ( fenoles, polifenoles, anilinas, aril-diaminas, fenoles metoxi-sustituídos, y otros), lo cual es una buena razón de su atracción para aplicaciones biotecnológicas. La enzima tiene potencial aplicación en procesos tales como en la delignificación de materiales lignocelulósicos y en el bioblanqueado de pulpas para papel, en el tratamiento de aguas residuales de plantas industriales, en la modificación de fibras y decoloración en industrias textiles y de colorantes, en el mejoramiento de alimentos para animales, en la detoxificación de polutantes y en bioremediación de suelos contaminados. También se la ha utilizado en Q.Orgánica para la oxidación de grupos funcionales, en la formación de enlaces carbono- nitrógeno y en la síntesis de productos naturales complejos. HIPOTESIS: Los hongos de podredumbre blanca, y en condiciones óptimas de cultivo producen distintos tipos de enzimas oxidasas, siendo las lacasas las más adecuadas para explorarlas como catalizadores en los siguientes procesos:  Delignificación de residuos de la industria forestal con el fin de aprovechar tales desechos en la alimentación animal.  Decontaminación/remediación de suelos y/o efluentes industriales. Se realizarán los estudios para el diseño de bio-reactores que permitan responder a las dos cuestiones planteadas en la hipótesis. Para el proceso de delignificación de material lignocelulósico se proponen dos estrategias: 1- tratar el material con el micelio del hongo adecuando la provisión de nutrientes para un desarrollo sostenido y favorecer la liberación de la enzima. 2- Utilizar la enzima lacasa parcialmente purificada acoplada a un sistema mediador para oxidar los compuestos polifenólicos. Para el proceso de decontaminación/remediación de suelos y/o efluentes industriales se trabajará también en dos frentes: 3) por un lado, se ha descripto que existe una correlación positiva entre la actividad de algunas enzimas presentes en el suelo y la fertilidad. En este sentido se conoce que un sistema enzimático, tentativamente identificado como una lacasa de origen microbiano es responsable de la transformación de compuestos orgánicos en el suelo. La enzima protege al suelo de la acumulación de compuestos orgánicos peligrosos catalizando reacciones que involucran degradación, polimerización e incorporación a complejos del ácido húmico. Se utilizarán suelos incorporados con distintos polutantes(por ej. policlorofenoles ó cloroanilinas.) 4) Se trabajará con efluentes industriales contaminantes (alpechínes y/o el efluente líquido del proceso de desamargado de las aceitunas). The lignocellulosic raw materials of the agroindustrial activities can be taken advantage as source of lignin, hemicellulose and cellulose. The chemical treatment of this material is not easy because the above mentioned material is recalcitrant enough to such an assault, due to the presence of the lignin. This can be achieved also using the white-rot fungi of the wood. It produces extracellular ligninolitic enzymes, fundamentally Laccase, which oxidizes the lignin to CO2. The enzyme has application in such processes as in the delignification of lignocellulosic materials and in the biobleaching of fibers for paper industry, in the treatment of waste water of industrial plants, in the discoloration in textile industries, in the improvement of food for ruminants, in the detoxification of polutants and in bioremediation of contaminated soils. HYPOTHESIS: The white-rot fungi produce different types of enzymes, being the laccases the most adapted to explore them as catalysts in the following processes:  Delignification of residues of the forest industry in order to take advantage of such waste in the animal feed.  Decontamination of soils and / or waste waters. The studies will be conducted for the design of bio reactors that allow to answer to both questions raised in the hypothesis. For the delignification process of lignocellulosic material they propose two strategies: 1- to treat the material with the fungi 2-to use the partially purified enzyme to oxidize the polyphenolic compounds. For the soil and/or waste water decontamination process, we have: 3- Is know that the enzyme protects to the soil of the accumulation of organic dangerous compounds catalyzing reactions that involve degradation, polymerization and incorporation to complexes of the humic acid. There will be use soils incorporated into different pollutants. 4- We will work with waste waters (alpechins or the green olive debittering effluents.

Synthetic and mechanistic studies of the Thia-Fries Rearrangement

A study has been undertaken of the published literature on the Fries rearrangement, thermal, photo and microwave, since its discovery in 1908. A resume of these publications and especially of those pertaining to the thia-Fries rearrangement of sulfamate esters, has been compiled. Phenyl sulfamate, phenyl N,N-dimethylsulfamate, phenyl N,N-diethylsulfamate and phenyl N,N-di-n-propylsulfamate and many of their substituted compounds have been synthesised and purified, a total of thirty nine esters. The sulfamates have been characterised by mp / bp, infrared, C, H and N microanalysis and mass spectrum. Many of these sulfamates, twenty six in total, have been rearranged to sulfonamides in the thia-Fries rearrangement, and subsequently purified. The products were characterised by mp / bp, infrared, C, H and N microanalysis and mass spectrum. Mechanistic studies of the sulfamates have been investigated, particularly phenyl N,N-dimethylsulfamate. The rearrangement with various catalysts and catalytic ratios, the effect of solvents on the rearrangement and many crossover experiments have been carried out to determine the molecularity i.e. whether it is an inter-, intra- or bimolecular reaction. The microwave induced thia-Fries rearrangement has been examined to determine what effect this irradiation has on the rearrangement. Photo thia-Fries rearrangement has also been investigated.

Conservation status assessment of the amphibians and reptiles of Uruguay

The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN Red List criteria. Out of 47 amphibian species, seven are listed as Critically Endangered (CR), five as Endangered (EN), one as Vulnerable (VU), three as Near Threatened (NT), and two as Data Deficient (DD); the remaining species are considered to be Least Concern (LC). Among the 64 species of reptiles evaluated, one is listed as Critically Endangered (CR), seven as Endangered (EN), two as Vulnerable (VU), one as Near Threatened (NT) and seven as Data Deficient (DD); the rest are considered to be Least Concern (LC). The use of these results as an additional criterion in the definition of protected areas in Uruguay will contribute towards the conservation of the aforementioned threatened species and their associated ecosystems.

Preparació de materials híbrids orgànico-inorgànics a partir de sals d'imidazoli

Estudi elaborat a partir d’una estada a l’ Ecole Nationale Supérieure de Chimie de Montpellier, França, durant 2006. S’han sintetitzat materials híbrids orgànico-inorgànics mitjançant el procés sol-gel i altres estratègies sintètiques. En alguns casos, s’ha intentat estructurar aquests materials, ja sigui per autoestructuració o per mitjà de tensioactius. Com a catalitzadors de les reaccions d'hidròlisi i policondensació s’han utilitzat àcids, bases i fluorurs. Els materials obtinguts s’han caracteritzat mitjançant diferents tècniques: BET (Brunauer-Emmett-Teller), TEM (microscopia electrònica de transmissió), SEM (microscòpia electrònica de rastreig), raigs X en pols , IR i RMN (ressonància magnètica nuclear) en estat sòlid. Amb aquests materials es pretén preparar catalitzadors heterogenis de Pd per reaccions d’acoblament creuat, i de Ru per reaccions de metàtesi. També s’han sintetitzat sals d'imidazoli amb cadenes hidrocarbonades llargues amb l'objectiu de preparar gels de sílice amb aquestes molècules atrapades dins la matriu inorgànica. Aquests materials s’utilitzaran com a organocatalitzadors i també es prepararan els corresponents catalitzadors de Pd per reaccions de Heck, Suzuki i Sonogashira. Les sals d’imidazoli s’han utilitzat com a tensioactius en la preparació de gels de sílice estructurats. Aquestes molècules han resultat ser cristalls líquids i s’han caracteritzar mitjançant DSC (differential scanning calorimetry), microscopia òptica i raigs X.