Microwave reactors are important tools in chemical synthesis, as they can lead to unprecedented reductions in reaction times and improved reaction yields. In order to scale-up the technology for greater throughput and industrial application, reactor types are moving from batch to continuous flow reactors. This research designed, built, verified and modeled a continuous flow microwave reactor. The reactor could operate under high temperature/high pressure conditions, and was connected to in-line gas chromatography/mass spectrometry, for real time sample analysis. Specifically, a pressure device was developed to enable the reactor to run under high pressure conditions (< 1100 psi) without the use of a conventional back-pressure device. The reactor design was verified using two chemical reactions, and an in-line analytic apparatus was developed to assess the potential for reactor operation with in-line GC/MS. Additionally, a computational fluid dynamic model was developed to better understand the heat and mass transfer inside the reactor.

Microwave reactors are important tools in chemical synthesis, as they can lead to unprecedented reductions in reaction times and improved reaction yields. In order to scale-up the technology for greater throughput and industrial application, reactor types are moving from batch to continuous flow reactors. This research designed, built, verified and modeled a continuous flow microwave reactor. The reactor could operate under high temperature/high pressure conditions, and was connected to in-line gas chromatography/mass spectrometry, for real time sample analysis. Specifically, a pressure device was developed to enable the reactor to run under high pressure conditions (< 1100 psi) without the use of a conventional back-pressure device. The reactor design was verified using two chemical reactions, and an in-line analytic apparatus was developed to assess the potential for reactor operation with in-line GC/MS. Additionally, a computational fluid dynamic model was developed to better understand the heat and mass transfer inside the reactor.

Simple low-cost temperature feedback control loop was created, using personal computer as control and data acquisition element. It controlled the temperature inside mircowave pressure reactor. Medium in reactor tank (volume about 600 ml) was calorified by 1,8 kW magnetron, which power was driven by PSD controller. The PC- process interface was made by USB data acquisition modul UD128A8D. The utility program was written. It implemented PSD controller and data acquisition function. Furhtermore it implemented interface which enabled user to set the technological curve (time-temperature relation). The protocol of experiment was automatically stored to Micosoft Excel file before the program’s termination.

Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-26T14:51:02Z No. of bitstreams: 1 DissMAF.pdf: 3997675 bytes, checksum: 3238bd54da33e9d0c201deb533005fa2 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-26T18:48:09Z (GMT) No. of bitstreams: 1 DissMAF.pdf: 3997675 bytes, checksum: 3238bd54da33e9d0c201deb533005fa2 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-26T18:48:18Z (GMT) No. of bitstreams: 1 DissMAF.pdf: 3997675 bytes, checksum: 3238bd54da33e9d0c201deb533005fa2 (MD5) / Made available in DSpace on 2016-09-26T18:48:26Z (GMT). No. of bitstreams: 1 DissMAF.pdf: 3997675 bytes, checksum: 3238bd54da33e9d0c201deb533005fa2 (MD5) Previous issue date: 2015-03-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Xylooligosaccharides (XOS) are short-chain polymers of xylose (2 to 7 units) which can be produced by enzymatic hydrolysis of the xylan from the lignocellulosic feedstocks. XOS have a great potential as probiotic ingredients, and when they are incorporated in diets, they can provide many health benefits. The worldwide interest in the use of lignocellulosic residues is constantly growing, and in this scenario the soybean hull arises as a potential residue of the Brazilian agroindustry. The bioconversion of these residues to value-added products requires suitable pretreatments to deconstruct/disorganize the recalcitrant lignocellulosic complex, separating its main fractions: cellulose, hemicellulose, and lignin. In this context, this work did evaluate different biomass pretreatments aiming to produce XOS by the action of a Bacillus subtilis endoxylanase. Initially, the conditions for maximum catalytic activity of this enzyme were evaluated changing pH, buffer, and temperature. Among these parameters, 50 mM citrate buffer, pH 5.5, and 45 oC were the one that gave highest activity. The in nature soybean hull (previously chemically characterized) was hydrolyzed with soluble endoxylanase with different enzyme loads (40, 80, and 100 U/g biomass) under preestablished pH and temperature, producing around 55 mg RS/g dry biomass. This result, though little expressive, showed the viability of XOS production from soybean hull. However, this approach requires a suitable pretreatment of the lignocellulosic biomass to improve the endoxylanase accessibility to the C-5 fraction. Several pretreatments were performed in the soybean hulls, such as, enzymatic deproteinization, hydrogen peroxide/acetic acid pretreatment, and organosolv-ethanol pretreatment. For some pretreatments, reagent concentration and reaction time were evaluated, as well as, sequential pretreatment. Besides, enzymatic hydrolysis of the in nature soybean hull under microwave irradiation was also evaluated. The deproteinization of the soybean hull was not very efficient to the enzymatic hydrolysis of the remnant solid (production of 30 mg RS/dry biomass). However, this pretreatment allows the protein recovery as a high nutritional value hydrolysate. The pretreatment of the deproteinized soybean hulls with hydrogen peroxide solution (5 M, 1 h) removed 56% lignin without cellulose losses. However, this pretreatment did not contribute to an efficient action of the endoxylanase to the hemicellulose fraction (production of around 30 mg RS/g dry biomass). The organosolv-(50% v/v)ethanol pretreatment of the deproteinized soybean hulls promoted the removal of around 50% lignin, with low solubilization of hemicellulose (<17%), producing a poor substrate for the endoxylanase. The organosolv pretreatments with 50 and 70% (v/v) ethanol of the in nature soybean hull were able to solubilize around 30% hemicellulose, allowing the production of around 76 and 49 mg RS/g dry biomass, respectively, after hydrolysis with endoxylanase. Finally, the microwave action on the lignocellulosic biomass probably decreased the biomass recalcitrance, because the hydrolysis of the in nature soybean hulls catalyzed by the endoxylanase (100 IU / g of biomass) yielded approximately 100 mg of RS/g dry biomass. On the other hand, the hydrolysis performed in a reactor under conventional heating produced only 52 mg RS/g dry biomass. The results of this work did show that the combination of microwave irradiation and enzymatic hydrolysis might be a promising alternative to produce XOS. Keywords: soybean hulls; xylo-oligosaccharides; pretreatments / Xilo-oligossacarídeos (XOS) são polímeros de xilose de cadeia curta (2 a 7 unidades) que podem ser obtidos por hidrólise enzimática da xilana presente na fração de hemicelulose dos materiais lignocelulósicos. XOS possuem um grande potencial como ingredientes prebióticos, e quando incorporados na dieta, podem fornecer muitos benefícios à saúde. O interesse mundial no aproveitamento de resíduos lignocelulósicos é cada vez maior, e no cenário nacional a casca de soja se destaca como um potencial resíduo da agroindústria brasileira. Para viabilizar a bioconversão desses resíduos em produtos de interesse comercial (etanol 2G e XOS, por exemplo) são necessários pré-tratamentos, que atuam desconstituindo/desorganizando a estrutura altamente recalcitrante do complexo lignocelulósico e separando as frações principais da biomassa: celulose, hemicelulose e lignina. Neste contexto, este trabalho teve por objetivo avaliar diferentes pré-tratamentos da biomassa para produzir sequencialmente XOS por ação de uma endoxilanase de Bacillus subtilis. Inicialmente as condições de máxima atividade catalítica dessa enzima foram avaliadas variando pH, tampão e temperatura. Dentre as variáveis estudadas, as que contribuíram para uma melhor atividade da endoxilanase foram tampão citrato de sódio (50mM) pH 5,5 e 45 °C. A casca de soja in natura (previamente caracterizada quimicamente) foi hidrolisada com endoxilanase solúvel com diferentes cargas enzimáticas (40, 80 e 100 U/g casca) nas condições de pH e temperatura pré-estabelecidas, produzindo em média 55 mg de AR/g biomassa seca. Esse resultado, embora pouco expressivo, demonstrou a viabilidade da produção de XOS a partir de casca de soja, requerendo, entretanto, um pré-tratamento adequado para melhorar a acessibilidade da endoxilanase à fração C-5 da biomassa. Os pré-tratamentos avaliados foram a desproteinização enzimática da casca, prétratamento com peróxido de hidrogênio e ácido acético e pré-tratamento organossolve-etanol, variando nestes, as concentrações de solventes, tempo de reação e pré-tratamentos sequenciais. Adicionalmente, realizou-se a hidrólise enzimática da casca de soja in natura em reator micro-ondas. A desproteinização da casca de soja mostrou-se ineficiente para a hidrólise da fração sólida remanescente com endoxilanase (produção de 30 mg de AR/g biomassa seca), embora esse pré-tratamento permita a recuperação de proteínas como um hidrolisado de alto valor nutricional. O pré-tratamento com peróxido de hidrogênio (5 M, 1 h) para casca de soja desproteinizada removeu 56% de lignina sem perdas de celulose, entretanto, este pré-tratamento não contribuiu para uma eficiente atuação da endoxilanase sobre a fração hemicelulósica (produção de aproximadamente 30 mg de AR/g biomassa seca). O pré-tratamento organossolve-etanol 50% (v/v) da casca de soja desproteinizada removeu em torno de 50% de lignina com baixa solubilização de hemicelulose (< 17%), gerando, portanto, um líquido com baixa concentração de substrato para a ação da endoxilanase. Os pré-tratamentos organossolve-etanol 50 e 70% (v/v) da casca de soja in natura foram capazes de solubilizar em torno de 30% da hemicelulose, sendo possível a produção de 76 e 49 mg de AR/g de biomassa seca, respectivamente, após hidrólise com endoxilanase. Por fim, a ação das microondas sobre a biomassa lignocelulósica provavelmente reduziu a recalcitrância da biomassa, pois a hidrólise da casca in natura com endoxilanase (100 U/g de casca) produziu aproximadamente 100 mg de AR/g de biomassa seca, ao contrário da hidrólise conduzida em reator com aquecimento convencional que produziu em torno de 52 mg de AR/g de biomassa seca. Os resultados deste trabalho indicam que a combinação de irradiação micro-ondas e hidrólise enzimática pode ser uma alternativa promissora para a produção de XOS.

Made available in DSpace on 2015-05-14T13:21:18Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 11661227 bytes, checksum: e157f4398306766375669b2e52ab9310 (MD5) Previous issue date: 2012-11-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, we describe the investigation of the Morita-Baylis-Hillman reaction in microwave reactor, under closed vessel conditions to prepare 40 adducts, six novel, using 30 aromatic aldehydes and isatin as electrophiles and acrylonitrile (62a) , methyl acrylate (2), hydroxyethyl acrylate (62b), 2,2-dimethyl-1 ,3-dioxalyl acrylate (62c) and 2,3-dihydroxypropyl acrylate (62d) as Michael acceptors catalyzed by 1, 4-diazabicyclo [2.2.2] octane (DABCO). Most adducts were synthesized efficiently in short reaction times and excellent yields (70-99%) using this reaction protocol. However, this synthetic methodology showed limitations for less reactive substrates due to formation of byproducts and in some cases the formation of the desired adduct was not obtained. The application of low temperatures and / or conventional room temperature protocol led to the adducts preparation in a chemoselective manner. We proved that the formation of 2-hydroxy (4-bromophenyl) methyl acrylate (43) is reversible at 120 ° C, which explains the restriction observed in the preparation of certain adducts using heating by microwave irradiation and successfully protocol employing temperature of 0º C. Preliminary evaluation of cytotoxic activity against cell lines of human leukemia HL-60 was performed, where the nitrilated isatin derivatives adducts (56a and 56b) were the most active. Preliminary studies of antimitotic activity in embryonic cells of sea urchin (Echinometra lucunter) performed with nitrilated adducts containing pyridine rings (49, 47, 20), nitro group (16, 38, 15) and bromine atom attached to the aromatic ring (42) revealed that except 47, all investigated adducts strongly inhibited stages of embryonic development of the first cleavage and morula. Moreover, experimental observations showed no inhibition of microtubule organization, induction of cell necrosis and toxicity of the adducts, suggesting that the blocking mechanism of action of protein synthesis and / or DNA. / Neste trabalho, nós descrevemos a investigação da reação de Morita-Baylis-Hillman em reator de micro-ondas, sob condições de vaso fechado para preparação de 40 adutos, sendo seis inéditos, utilizando 30 aldeídos aromáticos e a isatina como eletrófilos e acrilonitrila (62a), acrilato de metila (2), acrilato de hidroxietila (62b), acrilato de 2,2-dimetil-1,3-dioxalila (62c) e acrilato de 2,3-diidroxipropila (62d) como aceptores de Michael catalisada por 1,4-diazabiciclo [2.2.2] octano (DABCO). A maioria dos adutos foram sintetizados de forma eficiente em curtos tempos reacionais e excelentes rendimentos (70-99%) usando este protocolo reacional. No entanto, esta metodologia sintética apresentou limitações para substratos menos reativos, devido a formação de subprodutos e em alguns casos a não formação do aduto desejado. A aplicação de baixa temperatura e / ou protocolo convencional a temperatura ambiente conduziram a preparação dos adutos de forma quimiosseletiva. Provamos que a reação de formação do acrilato de 2-hidroxi(4bromofenil)metila (43) é reversível a 120° C, fato que explica a limitação observada na preparação de alguns adutos usando aquecimento por irradiação de micro-ondas e o sucesso no emprego de protocolo a temperatura de 0º C. A avaliação preliminar da atividade citotóxica contra linhagem de células de leucemia humana HL-60 foi realizada, onde os adutos nitrilados derivados da isatina (56a e 56b) foram os mais ativos. Estudos preliminares da atividade antimitótica em células embrionárias de ouriço do mar (Echinometra lucunter) realizados com adutos nitrilados contendo anéis piridínicos (49, 47, 20), grupo nitro (16, 38, 15) e átomo de bromo ligados ao anel aromático (42) revelaram que, exceto 47, todos os adutos investigados inibiram fortemente os estágios de desenvolvimento embrionário de primeira clivagem e mórula. Além disso, observações experimentais não demonstraram inibição da organização dos microtúbulos, indução de necrose celular e toxicidade por parte dos adutos, sugerindo como mecanismo de ação o bloqueio da síntese protéica e/ou de DNA.