Despite the growing interest in heterogeneous polymerization catalysis, the majority of the polymerization catalysts used industrially are single-use entities that are left in the polymer product. Recoverable and recyclable polymerization catalysts have not reached the industrial utility of single-use catalysts because the catalyst and product separation have not become economical. The successful development of recyclable transition metal polymerization catalysts must take a rational design approach, hence academic and industrial researchers need to further expand the fundamental science and engineering of recyclable polymerization catalysis to gain an understanding of critical parameters that allow for the design of economically viable, recoverable solid polymerization catalysts. Unfortunately, the rapid development of Atom Transfer Radical Polymerization over the past 10 years has not resulted in its wide spread industrial practice. Numerous reports regarding the immobilization of transition metal ATRP catalysts, in attempts to increase its applicability, have extended the fundamentals of recyclable polymerization catalysis. However, for industrial viability, more research is required in the area of how the catalyst complex immobilization methodology and support structure affect the catalyst polymerization performance, regeneration, and recyclability. A comprehensive rational catalyst design approach of silica-immobilized ATRP catalyst was undertaken to answer these questions and are discussed here.

Catalysis is an important field of study in chemical engineering and chemistry due to its application in a vast number of chemical transformations. Traditionally, catalysts have been developed as homogeneous molecular species or as heterogeneous insoluble materials. While homogeneous catalysts are typically very active and selective, they are difficult to recover. Conversely, heterogeneous catalysts are easy to recover and reuse, but they generally are less selective. To address these issues, the immobilization of homogeneous catalyst analogs onto solid supports has been a subject of research for the past few decades. Nonetheless, the effects of immobilization are still not completely predictable, and so continued effort is required to develop new immobilized catalysts as well as to develop a better understanding of how different parameters affect catalytic behavior. This dissertation presents the synthesis, characterization, and evaluation of new immobilized catalysts for different applications. First, a solid base catalyst supported on silica was developed and studied in the synthesis of cyclic carbonates from epoxides and carbon dioxide. Next, polymer and silica supported vanadium Schiff base catalysts were developed and evaluated for use in the oxidative kinetic resolution of alpha-hydroxy esters, an enantioselective reaction. Lastly, salen catalyst analogs with amine reactive functional groups were synthesized and characterized for grafting onto aminosilicas with different degrees of amine group isolation. The grafted catalysts were then tested to determine how catalyst spacing on the surface affects their behavior. Throughout the presentation of these results, comparisons are made amongst the new supported catalysts and relevant existing catalysts to discern general trends which could be applied to a wider range of immobilized catalysts. Finally, research opportunities for further improvements in these areas are suggested.

Title: Optimization of surface-enhanced Raman scattering spectroscopy for study of biologically important biomolecules and their interactions Author: Natália Šmídová Department: Institute of Physics of Charles University Supervisor of the doctoral thesis: Doc. RNDr. Marek Procházka, PhD. Abstract: The main goal of this thesis was to optimize surface-enhanced Raman scattering (SERS) spectroscopy for study of biologically important biomolecules. For that purpose we focused on substrates based on gold colloidal nanoparticles immobilized to silanized glass plates. Stable, uniform and highly reproducible SERS-active substrates have been prepared by using aminopropyltrimethoxysilane and citrate- reduced gold nanoparticles thermally stabilized after their immobilization. Model biomolecules 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin (TMPyP) and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) were studied on these substrates by using a classical Raman spectrometer in macro-mode and a confocal Raman microspectrometer. Conditions for SERS spectroscopy of porphyrins were optimized with respect to sensitivity and reproducibility. SERS microspectroscopy showed several advantages over SERS measurements in macromode: possibility of surface spectral mapping, easier manipulation with samples, shorter...

Organophosphates and carbamates are potent inhibitors of the neurotransmitter acetylcholinesterase. This inhibition results in the blocking of nerve signal transference into the post synaptic neuron leading to loss of muscle action and death. Because of the universal mechanisms of signal transduction in animals, these inhibitors have been widely used as agricultural pesticides as well as chemical warfare agents (nerve agents). Health issues associated with pesticide usage result from the fact that both the pesticides and their breakdown products often end up in water and food sources as well as in the soil. As a result, there has been an increase in the number of studies aimed at the detection of these pesticides in the environment. One popular research area is enzyme based biosensor construction. Some important criteria for consideration during the construction of biosensors are the importance of a suitable solid support as well as the enzyme immobilisation method. Recently, there has been increased interest in using nano-scale material e.g. using nanoparticles as enzyme support material. This is largely due to their advantages such as large surface area to volume ratio as well as reduced mass transfer resistance. Electrospinning is a straight forward and cost effective method for producing nanofibres from any soluble polymer(s). The applications of electrospun nanofibres have been reported in clinical studies, biofuel production as well as bioremediation. In this study two polymers were selected: nylon for its mechanical stability and chitosan for its biocompatibility and hydrophilicity, for the fabrication of electrospun nanofibres which would function as immobilisation support material for acetylcholinesterase. The first objective of this study was to electrospin nanofibres from a nylon-6 and chitosan blend solution. A binary solvent system consisting of formic acid and acetic acid (50:50) successfully dissolved and blended the polymers which were subsequently electrospun. Scanning electron microscopy characterisation of the nanofibres showed that (i) a nylon-6: chitosan ratio of 16%: 3% resulted in the formation of bead free nanofibres and (ii) the fibres were collected in non-woven mats characterised by different size nanofibres with average diameters of 250 nm for the main fibres and 40 nm for the smaller nanofibres. Fourier transform infra-red (FT-IR) analysis of the nanofibres indicated that a new product had been formed during the blending of the two polymers. The second aim of the study was to carry out a facile immobilisation of electric eel acetylcholinesterase via glutaraldehyde (GA) cross-linking. Glutaraldehyde solution 5% (v/v) resulted in the immobilisation of 0.334 mg/cm² of acetylcholinesterase onto the nanofibres. The immobilisation procedure was optimised with reference to acetylcholinestease and crosslinker concentrations, incubation time and the cross-linking method. A comparative investigation into the optimum pH and temperature conditions, pH and thermal stabilities, substrate and inhibition kinetics was then carried out on free and immobilised acetylcholinesterase. The final objective of this study was to determine the storage stabilities of the immobilised and free enzymes as well as the reusability characteristics of the immobilised acetylcholinesterase. Several conclusions were drawn from this study. Acetylcholinesterase was successfully immobilised onto the surface of nylon-6:chitosan nanofibres with retention of its activity. There was a shift in the pH optimum of the immobilised acetylcholineseterase by 0.5 units towards a neutral pH. Although both free and immobilised acetylcholinesterase exhibited the same optimum temperature, immobilised acetylcholinesterase showed enhanced thermal stability. In terms of pH stability, immobilised acetylcholinesterase showed greater stability at acidic pH whilst free acetylcholinesterase was more stable under alkaline pH conditions. Relative to free acetylcholinesterase, the immobilised enzyme showed considerable storage stability retaining ~50% of its activity when stored for 49 days at 4°C. Immobilised acetylcholinesterase also retained > 20% of its initial activity after 9 consecutive reuse cycles. When exposed to fixed concentrations of carbofuran or demeton-S-methyl sulfone, immobilised acetylcholinesterase showed similar inhibition characteristics to that of the free enzyme. The decrease in enzyme activity observed after immobilisation to the nanofibres may have been due to several reasons which include some enzyme molecules being immobilised in structural conformations which reduced substrate access to the catalytic site, participation of the catalytic residues in immobilisation and enzyme denaturation due to the reaction conditions used for acetylcholinesterase immobilisation. Similar observations have been widely reported in literature and this is one of the major drawbacks of enzyme immobilisation. In conclusion, nylon-6:chitosan electrospun nanofibres were shown to be suitable supports for facile acetylcholinesterase immobilisation and the immobilised enzyme has potential for use in pesticide detection. Future recommendations for this study include a comparative study of the GA cross-linking method for AChE immobilisation which will lead to more intensely bound enzyme molecules to prevent non-specific binding. An investigation into the effect of inhibitors on stored immobilised AChE, as well as reactivation and reuse studies, may also be useful for determining the cost-effectiveness of reusing immobilised AChE for pesticide detection in environmental water samples. Several models have been designed for the determination of the kinetic parameters for immobilised enzymes. These take into account the mass transfer resistance as well as the overall charge of the immobilisation matrix. The use of these models to analyse experimental data will give a clear understanding of the effects of immobilisation on enzyme activity

Made available in DSpace on 2014-10-09T12:33:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:58Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientador: Roberto Alves de Oliveira / Banca: Marcelo Zaiat / Banca: Tania Leme de Almeida / Resumo: Neste trabalho foi avaliado o desempenho de três reatores anaeróbios horizontais instalados em série, em escala de bancada, com volume de 1,2 L cada, para o tratamento de águas residuárias do beneficamento do café por via úmida. Foi utilizado um reator anaeróbio horizontal com manta de lodo (R1) e dois de leito fixo, preenchidos com anéis de bambu (R2) e fibras da casca de coco (R3) como meio suporte. O reator R1 foi inoculado com lodo proveniente de reator UASB tratando águas residuárias de suinocultura. Os tempos de detenção hidráulica (TDH) aplicados aos reatores anaeróbios horizontais (R1+R2+R3) foram de 90, 72 e 54 h resultando em cargas orgânicas volumétricas médias (COV) de 12,8, 13,2 e 19,7 kg DQOtotal (m3 d)-1, nos ensaios 1, 2 e 3, respectivamente. Os valores médios da DQO total do afluente foram de 16002, 13198 e 14774 mg L-1, nos ensaios 1, 2 e 3, respectivamente. Os valores médios da DQO total dos efluentes dos reatores R1, R2 e R3 foram 6424, 4067 e 2975 mg L-1 , 6807, 5232 e 4081 mg L-1 e 8154, 6871 e 5700 mg L-1 nos ensaios 1, 2 e 3, respectivamente. As eficiências médias de remoção de DQO total no sistema de tratamento com os três reatores, foram de 76, 69 e 61%, nos ensaios 1, 2 e 3, respectivamente. A produção volumétrica média foi de 1,70, 1,25 e 0,70 L CH4 (L reator d)-1 no conjunto dos reatores, (R1+R2+R3), respectivamente. As eficiências médias de de remoção de DQOtotal, SST, e fenóis totais no conjunto de reatores (R1+R2+R3) não apresentaram diferença significativa e foram de 76, 69 e 61%, de 77, 81, 82% e de 58, 62 e 69% nos ensaios 1, 2 e 3, respectivamente. Os valores médios de pH nos efluentes dos reatores variaram de 6,2 a 7,9. A concentração média de ácidos voláteis totais do afluente e efluente do R3 foram de 2206, 1630 e 1732 mg CH3COOH L-1 e de 168, 1269 e 1220 mg CH3COOH L-1, nos ensaios 1, 2 e 3, respectivamente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work it was evaluated the efficiency of three horizontal anaerobic reactors installed in series, in bench scale (volume of 1,2 L each), one with sludge blanket (R1) and two of fixed bed filled out with bamboo rings (R2) and coconut fibers (R3) as it supports. The reactor R1 was inoculated with sludge originating from reactor UASB treating swine residual water. These reactors were fed whit wastewater from the coffee pulping originating by hand pulping of the dry coffee beans, simulating the wastewater of the mechanical pulping of the coffee beans. Each reactor was submitted at hydraulic detention time (HDT) of 30, 24 and 18 h resulting in organic load rate (OLR) of 12,8, 13,2 and 19,7 kg COD (m3 d)-1, in the rehearsals 1 and 2, respectively. The average values of total COD of the influent in the rehearsals 1, 2 and 3 were of 16002, 13198 and 14774 mg L-1, respectively. The average values of total COD of the effluent of the reactors R1, R2 and R3 were 6424, 4067 and 2975 mg L-1, 6807, 5232 and 4081 mg L-1 and 8154, 6871 and 5700 mg L-1 in the rehearsals 1, 2 and 3, respectively. The average efficiencies of removal of total COD in the treatment system with the three reactors, in the rehearsals 1, 2 and 3 were of 76, 69 and 61%, respectively. The content of methane in the biogas was of 76, 69 and 61% and the maximum volumetric methane production was of 1,7 L CH4 (L reactor d)-1 in the system of treatment, with OLR of 12,8 kg DQO (m3 d)-1 and HDT of 30 h, in the second rehearsal the average content of methane was 71, 64 and 17% in the reactors R1, R2 and R3, respectively with volumetric methane production of 1,21 L CH4 (L reactor d)-1 in the system of treatment. The average values of pH in the effluent of the reactors ranged from 6,2 to 7,9. In the rehearsal 1 the average concentration of total volatile acids of the influent was of 2206 mg CH3COOH L-1 and in the effluent... (Complete abstract click electronic access below) / Mestre

Orientadores: Maria Helena Andrade Santana, Heizir Ferreira de Castro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-27T20:07:32Z (GMT). No. of bitstreams: 1 Soares_CleideMaraFaria_M.pdf: 5966176 bytes, checksum: 181a14205ef4b15d71734d115dd39efe (MD5) Previous issue date: 2000 / Resumo: A metodologia de preparação do biocatalisador pode influenciar no processo catalítico. De acordo com estudos anteriores a lipase de Candida rugosa pode ser imobilizada com presença de alta atividade em sílica de porosidade controlada (SPC) ativada com glutaraldeído. Neste trabalho, foram desenvolvidas estratégias para otimizar a estabilidade operacional desta preparação de lipase imobilizada. Para atingir este propósito, foram testados diferentes tipos de agentes estabilizantes com a finalidade de proteger a enzima de efeitos de agregação ou desnaturação que ocorrem devido à presença dos silanos usados durante a formação da matriz de sílica. Os aditivos usados como estabilizantes foram as proteínas (albumina e lecitina) e os polímeros orgânicos (P-ciclodextrina e polietilenoglicol) e seus efeitos foram comparados ao controle (lipase imobilizada sem aditivo). A metodologia de planejamento experimental foi utilizada para selecionar o aditivo que fornecesse maior rendimento de imobilização. Foram realizados três planejamentos fatoriais completos 22, com repetição no ponto central para avaliar a variável resposta, em função do tipo de aditivo e concentração de enzima. Entre todos os aditivos testados, rendimentos mais elevados foram obtidos quando PEG-1500 foi utilizado como agente estabilizante. De acordo com os resultados estatísticos, um novo planejamento fatorial completo 22, com repetição no ponto central foi realizado, para avaliar o rendimento de imobilização em função da concentração de PEG-1500 e lipase. Utilizandose da metodologia de superficie resposta, obteve-se o seguinte modelo matemático para o rendimento de imobilização: Y = 50,91+4,70X1 - 9,89X2 + 4,04 XI X2 onde X I e X2 correspondem aos valores codificados para as variáveis concentração de aditivo e enzima, respectivamente. A estabilidade operacional das preparações de lipase imobilizada na presença de PEG-1500 foi determinada na síntese de butirato de butila em regime de bateladas consecutivas. Adotando a estratégia proposta neste trabalho, o tempo de meia vida da lipase imobilizada em SPC foi aumentado em 13 vezes, quando comparado com o tempo de meiavida do controle (lipase imobilizada em SPC sem aditivo) / Abstract: The method for preparing the biocatalyst can influence the catalytic processo In agreement with previous studies Candida rugosa lipase can be immobilized with high activity retention on silanized controlled pore silica (CPS) activated with glutaraldehyde. This work aimed at improving the performance of the immobilized form in long-term operation. Five additives were tested in the immobilization step in order to select the most activity derivative for esterification reactions. This strategy is suggested to protect the enzyme from aggregation effects or denaturation that occur due to the presence of silane precursors used in the formation of the silica matrix. Proteins (albumin and lechitin) and polymers (B-cyclodextrin and polyethyleneglycol) were added during the immobilization procedure and their effects are reported and compared with the behavior of the immobilized biocatalyst in the absence of additive. The methodology of experimental design was used to select the most efficient additive considering the coupling yield as a response variable. Three 22 full factorial design with repetitions at the center point were employed to evaluate the immobilization yield as a function of additive type and lipase loading. The best stabilizing effect was found when small amounts of PEG-1500 and lipase were added simultaneously to the lipase onto support. According to statistic results, further 22 full factorial design with 2 repetitions at the center point were employed to evaluate the immobilization yield as a function of PEG and lipase concentrations. A response surface methodology permitted to obtain the following mathematical model for immobilization yield: Y = 50.91+4.70X1 - 9.89X2 + 4.04 Xl X2 where: Xl and X2 are the codified values for additive PEG-1.500 and enzyme concentrations, respectively. This immobilized system was used to perform esterification reactions under repeated batch cycles (for the synthesis of butyl butyrate as a model). The half-life of the lipase immobilized on CPS in the presence of PEG-1500 was found to increase 13 times when compared with the control (immobilized lipase on CPS without additive) / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Orientador: Telma Teixeira Franco / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-28T03:46:25Z (GMT). No. of bitstreams: 1 Sousa_KathiaAssisde_M.pdf: 2724531 bytes, checksum: 3490f460776b8b8cf4564482c815165b (MD5) Previous issue date: 2001 / Resumo: Foram investigadas estabilidade frente a pH e temperatura e condições ótimas da enzima peroxidase do extrato bruto da casca da soja (Glycine max). Foi verificada a afinidade entre a enzima e íons cobre imobilizados no gel "Chelating Sepharose FastFlow" (CSFF) e também foi estudado o efeito do pH sobre a adsorção desta enzima. Foram construídas isotennas de adsorção para a peroxidase do extrato bruto de casca da soja e para as peroxidases padrão de soja e de nabo (horseradish), para verificar a capacidade máxima de adsorção do complexo CSFF-IDA-CU2+ para estas enzimas. Curvas de ruptura para a peroxidase do caldo bruto de casca da soja foram construídas para estudar a eficiência do complexo na adsorção da enzima. A purificação da peroxidase do extrato bruto da casca da soja foi estudada na coluna HR 5/5 empacotada com o complexo CSFF­IDA-CU2+ equilibrado com tampão fosfato de sódio O,IM a pH 6,0. Foi verificado que a peroxidase do extrato bruto da casca da soja apresentou condições ótimas de atividade a pH 4,5, mostrou-se estável por três horas em temperaturas entre 1 e 55°C. Foi observado que a adsorção mais seletiva da peroxidase do extrato bruto de casca da soja se deu a pH 6,0, quando 51% da enzima foi retida após dez minutos de contato entre a peroxidase e o complexo CSFF -IDA-Cu2+ a 25°C em tampão fosfato de sódio O,IM. A adsorção das peroxidases da casca da soja, padrão comercial de nabo e padrão comercial de soja no complexo CSFF-IDA-Cu2+ obedeceu ao modelo proposto por Langmuir. Com a construção das curvas de ruptura foi verificado que a pH 6,0 houve a melhor seletividade na separação da atividade de peroxidase, quando 96,9% de atividade foi recuperada. Na adsorção da peroxidase do extrato bruto da casca da soja na coluna HR 5/5 empacotada com CSFF-IDA-CU2+ a pH 6,0, foi obtido um fator de purificação de 5,9 vezes com um rendimento de 83,4% / Abstract: The conditions for the soybean hull peroxidase activity were investigated for pH and temperature. It was observed that the best pH for maximum activity was at 4.5, however the activity was only 5% reduced at pH values 5.0 and 5.5 and was 20% reduced for pH's between 6.0 and 7.0 and 45% reduced at pH 8.0. It was stable at this pH interval for four hours period, however, it lost 20% activity at pH 4.5 after one hour incubation. Best temperature for the enzyme active was 55 °C and it was stable from 1 to 55 °C for at least three hours. The affinity between the soybean hull peroxidase and copper ions immobilized in a solid matrix was investigated. The maximum capacity ofthe CSFF-IDA-CU2+ to interact with the enzyme was calculated by plotting the concentrations of the proxidase found in the liquid phase in equilibrium with the peroxidase concentrations found in the solid phase (isotherms). Breakthrough curves were built to study the efficiency ofCSFF-IDA-CU2+ bed to adsorb the peroxidase of soybean hulI and also two standards peroxidases commercially available from soybean and ITom horseradish. The effect of pH on the adsorption of the enzyme was also investigated and it was observed that the most selective adsorption of the soybean hulI peroxidase was at pH 6.0. Purification of the soybean hull peroxidase was studied in the column HR 5/5 packed with the complex CSFF-IDA-CU2+ in 100 mM phosphate buffer at pH 6.0. The adsorption of the soybean hull peroxidase, soybean and horseradish peroxidases by the CSFF-IDA-CU2+ was observed to folIow Langmuir model. The final peroxidase purified by the process developed in this work showed that the specific activity of the enzyme was about 5.9 fold higher than that of cru de extract and the yield was about 83.4% / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Made available in DSpace on 2014-10-09T12:33:56Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:58Z (GMT). No. of bitstreams: 0 / A nanociência e a nanotecnologia vêm abrindo inúmeros desenvolvimentos de dispositivos e sistemas em escala nanométrica, com novas organizações moleculares, propriedades e funções distintas. Nesse contexto, as nanopartículas magnéticas poliméricas são compósitos formados por materiais magnéticos com tamanhos de partículas entre 1 e 100 nm combinados com polímeros funcionais. São materiais bem conhecidos e têm sido amplamente estudados devido às suas aplicações em diversas áreas tecnológicas. Nas áreas biológica e médica, as aplicações incluem separação e imobilização de enzimas e proteínas, melhoria nas técnicas de imagem de ressonância magnética para diagnóstico e sistemas de liberação controlada de fármacos. Neste trabalho, proteínas foram imobilizadas na superfície de um biopolímero combinado com partículas superparamagnéticas de magnetita para formar o compósito magnético. Utilizou-se o biopolímero quitosana, reticulada e funcionalizada com glutaraldeído, aplicável em ensaios biológicos. Obtiveram-se 3 tipos de compósitos magnéticos, os quais foram nomeados QM1Glu, QM2NaGlu e QM3Glu. Foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura, magnetometria de amostra vibrante, calorimetria exploratória diferencial, termogravimetria e espectroscopia por infravermelho. Foram avaliados quanto à imobilização das proteínas albumina de soro bovino (SAB), colágeno e tripsina. A imobilização das proteínas no biopolímero ocorreu em 30 min de incubação. O compósito magnético de quitosana não funcionalizada (QM3) também foi avaliado. Para a tripsina verificou-se que QM3 apresentou maior potencial de imobilização do que QM3Glu. Após 30 dias, QM3-Trip e QM3Glu-Trip ainda apresentavam a tripsina ativada. Foram demonstradas a atividade e a cinética enzimática da QM3Glu-trip com o substrato BApNA. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Biodiesel is a mixture of fatty acid alkyl esters produced by the reaction between vegetable oils and short chain alcohols, like methanol and ethanol, using a catalyst that can be acid, basic or enzymatic. However, the high cost of the raw material when refined vegetable oil is used, have made biodiesel production economically unattractive. Therefore, research with waste oils has increased, showing the technical viability of the production of biodiesel using the residential and industrial residues as raw material. Another variable that has influenced this type of reaction is the type of alcohol. In Brazil, the use of ethanol is interesting because the country has become one of the top worldwide producers of ethanol from vegetables sources, a cheaper and less toxic product than methanol, decreasing our petroleum dependence. The type of catalyst also influences biodiesel production. Alkali is the catalysts that is more often used in industry, but when the vegetable oil has a high acid value, it can not be used because soap is produced, diminishing the esters yield. In this case an acid or an enzyme is used as a catalyst. Based on the previous explanation, the results of this work correspond to the study of enzymatic production of biodiesel using waste oil and ethanol. The immobilized Candida antarctica lipase (Novozym 435) behavior was studied in the oleic acid esterification, studying the effect of the variables that has influence in the process. The variables chosen were: temperature (30 â 50oC), molar ratio acid:alcohol (1:1 â 1:6) and water content (0 â 20%). The reaction were performed in closed reactors with a capacity of 250 mL containing 10 g of oil, a known amount content of alcohol, pre-determined by experimental design and enzyme content of 5% p/p, based on the oil mass. The reaction medium was kept under constant stirring, 200 rpm. Maximum conversion of 88,36% was achieved when high molar ration, the lower temperature and water content values were used. However, by the kinetic study, it can be concluded that it is not necessary to use an alcohol excess to achieve good conversions. After that, the behavior of Candida Antarctica lipase B immobilized in chitosan was studied in acid oleic esterification. A slower initial rate of reaction was observed in comparison to Novozym 435. The behavior of both lipases was also studied in the esterification of waste coconut oil, showing good stability and giving a conversion of about 80% in 60 minutes. Both biocatalyst could be reused 10 times, keeping the same activity. In order to compare the behavior of Novozym 435 in two different mediums, an experimental design was performed with waste cotton oil, which had a low acid value. The same negative influence of the temperature and molar ratio was observed, but with a high reaction time, getting a maximum conversion of 82,66% in 72 hours of reaction. To calculate the conversions, the decreasing of the acid value was used when the raw material had a high acid value, and when the raw material had a low acid value the glycerol production was used. / O biodiesel à uma mistura de Ãsteres alquÃlicos de Ãcidos graxos resultante da reaÃÃo entre Ãleos vegetais e Ãlcoois de cadeia curta, como metanol ou etanol, auxiliada por um catalisador, que pode ser Ãcido, bÃsico ou enzimÃtico. Entretanto, o alto custo da matÃria-prima quando se utiliza Ãleo vegetal de grau alimentÃcio tem inviabilizado economicamente a produÃÃo desse biocombustÃvel. Por isso, as pesquisas com Ãleo residual tem aumentado, mostrando a viabilidade tÃcnica da produÃÃo de biodiesel a partir de resÃduos residenciais e industriais. Outro fator que influencia a reaÃÃo de produÃÃo de biodiesel à o tipo de Ãlcool. No Brasil, o uso do etanol à interessante desde que o nosso paÃs se tornou um dos maiores produtores mundiais de etanol vegetal, um produto mais barato e menos tÃxico que o metanol, diminuindo assim a nossa dependÃncia do petrÃleo. O catalisador tambÃm exerce influÃncia nesse tipo de reaÃÃo. Os catalisadores mais usados industrialmente sÃo as bases, mas quando o Ãleo vegetal tem um alto teor de Ãcidos graxos livres, o que acontece, geralmente, com os Ãleos residuais, nÃo à possÃvel usar catalisador bÃsico por favorecer a formaÃÃo de sabÃo e diminuir o rendimento em Ãsteres. Nesse caso, usa-se um catalisador Ãcido ou enzimÃtico. Partindo dessa premissa, os resultados constantes nessa dissertaÃÃo correspondem ao estudo da produÃÃo enzimÃtica de biodiesel utilizando Ãleo residual e etanol. Avaliou-se o comportamento da lipase comercial imobilizada de CÃndida antarctica tipo B (Novozym 435) na esterificaÃÃo do Ãcido olÃico comercial, estudando as variÃveis que influenciam no processo. As variÃveis escolhidas foram: temperatura (30-50o C), razÃo molar Ãcido:Ãlcool (1:1-1:6) e a concentraÃÃo de Ãgua presente no meio (0-20%). As reaÃÃes foram conduzidas em erlenmeyers de 250 mL fechados contendo 10 g de Ãleo e a quantidade de Ãlcool prÃ-determinada pelo planejamento de experimentos, mantendo-se a agitaÃÃo fixa em 200rpm e a concentraÃÃo de enzima em 5% m/m baseada na massa de Ãleo medida, obtendo-se uma conversÃo mÃxima de 88,36% na condiÃÃo de maior razÃo molar, menor temperatura e menor concentraÃÃo de Ãgua. Entretanto, pelo estudo cinÃtico concluÃ-se que nÃo à necessÃrio um excesso de Ãlcool para conseguir boas conversÃes. Em seguida, avaliou-se o comportamento de uma lÃpase do tipo B de CÃndida antarctica imobilizada em quitosana na esterificaÃÃo do Ãcido olÃico, observando um comportamento semelhante ao da Novozym 435 mas com uma taxa inicial de reaÃÃo mais lenta. Avaliou-se tambÃm o comportamento das duas lÃpases na esterificaÃÃo do Ãleo de coco residual Ãcido, observando uma boa estabilidade para ambos os biocatalisadores que forneceram uma conversÃo acima de 80% com 60 minutos de reaÃÃo e puderam ser reutilizados por no mÃnimo 10 vezes consecutivas sem perda considerÃvel de atividade. Para comparar o comportamento da Novozym 435 em dois meios distintos, realizou-se um planejamento experimental fatorial com um Ãleo de algodÃo residual de baixa acidez livre, observando a mesma influÃncia negativa da temperatura e da razÃo molar entre reagentes, mas com um tempo de reaÃÃo maior, pois uma conversÃo mÃxima de 82,66% sà foi atingida com 72 horas de reaÃÃo. Para o cÃlculo da conversÃo, utilizou-se a reduÃÃo do Ãndice de acidez quando a matÃria-prima tinha um alto teor de Ãcidos graxos livres e o mÃtodo do periodato de sÃdio na determinaÃÃo da glicerina quando a matÃria-prima tinha uma baixa acidez livre.