Na Ficha Catalogr?fica consta o t?tulo: "Monitoramento qu?mico da composi??o e da a??o do biodiesel do ?leo de am?ndoa da maca?ba no contato direto com a?o carbono e a?o carbono galvanizado". / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-11-01T18:00:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-11-10T11:52:57Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) / Made available in DSpace on 2018-11-10T11:52:57Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) claudia_eliane_dias_batista.pdf: 1707707 bytes, checksum: f480bf5d3fe108357404021690844f2f (MD5) Previous issue date: 2018 / O biodiesel ? uma importante fonte alternativa de energia, pois ? derivado da biomassa fotossint?tica de plantas oleaginosas. ?leos de muitas esp?cies de plantas t?m sido investigados por serem material precursor para a produ??o de biodiesel. Maca?ba (Acrocomia aculeata) ? uma palmeira nativa do Brasil, cuja fruta tem uma propor??o significativa de ?leo, com potencial real para a produ??o industrial de biodiesel. Existe uma ampla gama de quest?es ainda a serem sistematicamente exploradas, a fim de se obter uma vis?o adequada do manejo racional da cultura da palma, extra??o e processamento do ?leo para a produ??o e armazenamento comercial do biodiesel. O comportamento qu?mico dos ?steres met?licos de ?cidos graxos do ?leo da am?ndoa de maca?ba e a lixivia??o de elementos met?licos por contato dos a?os carbono usados na constru??o de tanques e dutos s?o o foco principal deste trabalho experimental. A composi??o em ?steres met?licos do biodiesel obtido da rea??o de transesterifica??o de triacilglicer?is do ?leo de am?ndoa da maca?ba com metanol, em contato direto com os a?os carbono ASTM A283 grau C e API X65 galvanizados e n?o galvanizados foi monitorada. A lixivia??o de elementos qu?micos da estrutura dos a?os carbono foi tamb?m investigada. Os resultados obtidos por espectroscopia M?ssbauer neste trabalho tamb?m mostraram que o contato com o biodiesel de maca?ba confere prote??o aos a?os n?o galvanizados contra a corros?o oxidativa no contato direto com o ar. Al?m disso, observou-se ainda a forma??o de esp?cies qu?micas contendo ferro, nomeadamente magnetita (Fe3O4) e w?stita (Fe1-xO), na superf?cie das barras de a?o n?o galvanizado quando em contato direto com o ar, mas sem contato com o biodiesel; nenhum ?xido de ferro foi detectado nas barras de a?o usadas no biodiesel, monitoradas at? 105 dias de armazenamento. As taxas de corros?o s?o baixas, de acordo com a norma NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. O biodiesel do ?leo da am?ndoa da maca?ba tem 63,44 massa% de ?steres de ?cidos graxos saturados. Uma condi??o que assegura relativamente alta estabilidade oxidativa do combust?vel, mesmo em contato (na presente experi?ncia, por imers?o) com o a?o carbono API ou ASTM, galvanizado ou n?o. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018. / Biodiesel is an important alternative source of energy, as it is derived from the photosynthetic biomass of oleaginous plants. Oils of many plant species have been investigated for being precursor material for the production of biodiesel. Maca?ba (Acrocomia aculeata) is a native palm in Brazil, whose fruit has a significant proportion of oil, with real potential for the industrial production of biodiesel. There is a wide range of issues still to be systematically explored, in order to achieve an adequate view of the rational crop management of the palm, extraction and processing of the oil for the production and the commercial storage of biodiesel. The chemical behavior of the fatty acid methyl esters from the maca?ba oil and the leaching of metal elements put directly in contact with carbon steels used in the construction of tanks and pipelines are the main focus of the present experimental work. The composition in methyl esters of the biodiesel obtained from the transesterification reaction of triacylglycerols of the maca?ba fruit kernel oil with methanol, in direct contact with the galvanized and non-galvanized carbon steels ASTM A283 grade C and API X65. The M?ssbauer spectroscopy results obtained in this work also showed that the contact with the maca?ba biodiesel gives protection to the non - galvanized steels against the oxidative corrosion in direct contact with air. Also the formation of iron-bearing chemical species, namely magnetite (Fe3O4) and w?stite (Fe1-xO), on the surface of the non-galvanized bar steels when in direct contact with air; no such iron oxide was detected on the steel bars used in the biodiesel, by monitoring up to 105 days of storage. But the corrosion rates are low, according to the NACE-RP0775, Standard Recommended Practice: Preparation, Installation, Analysis, and Interpretation of Corrosion Coupons in Oilfield Operations. These results allow better evaluate and more adequately specify conditions of storage and transportation of biodiesel obtained from the maca?ba oil. The biodiesel of the maca?ba almond oil has 63.44 mass% of esters of saturated fatty acids. A condition that ensures relatively high oxidative stability of the fuel, even in contact (in the present experiment, by immersion) with API or ASTM carbon steel, galvanized or not.

Made available in DSpace on 2015-03-13T17:10:27Z (GMT). No. of bitstreams: 1 GeovanyPGD.pdf: 1787770 bytes, checksum: c8df50f7d51101a4c3cc2bdd4d9910ac (MD5) Previous issue date: 2007-12-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The objective of the current piece of research is to reflect upon the diverse changes that have occurred in the social and spatial dynamics of the Maca?ba fair in the period between 1960 and 2006. During the second half of the 19th century, Maca?ba had in the commerce one of this principle economic base a contribution for which the city became one of the main commercial warehouses of the East coast of the Rio Grande do Norte region. This helped lead to the growth of Maca?ba s fair, which proved to be one of the most important existing in the state until the 1970 s. In the last two decades of the 20th century, certain elements represented challenges to the fair at Maca?ba. These challenges stimulated substantial changes in the fair s dynamics which include the growth and expansion of the commercial and service sector, primarily though supermarkets; consolidation among the commercial and distribution networks, represented by the Central Office of Supply of the Rio Grande do Norte S/A (Ceasa/RN), by the wholesale and refrigeration companies; and the modernization of transportation methods, which permitted an expanded reach for these networks. Even with all these changes, the fair continues to be one of the strongest aspects of the city being the center of resistance against the surge of new forms of commerce and consumption in the city (notable the supermarkets) and the diffusion of other aspects of globalization. The fair has economic importance, as it offers a popular marketplace for the commercialization of very different products and a means for supplying goods to the residents of the city and the rural communities of Maca?ba and the surrounding municipalities; and socio-cultural importance in that the fair is a place where popular tradition is expressed, a place where a great number of parallel activities occur, a place for meeting again and again, of conversations, of manifestations of culture and art, and of socialization in all of its dimensions / O presente trabalho de pesquisa objetiva fazer uma reflex?o sobre as diversas modifica??es ocorridas na din?mica socioespacial da feira de Maca?ba no per?odo compreendido entre 1960 e 2006. Durante a segunda metade do s?culo XIX, Maca?ba teve no com?rcio uma das principais bases econ?micas o que contribuiu para que a cidade fosse o principal entreposto comercial do litoral leste do Rio Grande Norte. Esta condi??o propiciou o surgimento de sua feira, a qual se destacou como uma das principais existentes no estado at? por volta da d?cada 1970. Nas ?ltimas duas d?cadas do s?culo XX, alguns elementos representaram fatores de concorr?ncia para a feira de Maca?ba, o que possibilitou modifica??es substanciais na sua din?mica, dentre os quais se destacam: o crescimento e a expans?o do setor de com?rcio e de servi?os, atrav?s principalmente dos supermercados; a consolida??o das redes de comercializa??o e distribui??o, representado pela Central de Abastecimento do Rio Grande do Norte S.A(Ceasa/RN), pelas empresas atacadistas e pelos frigor?ficos; e, a moderniza??o dos meios de transportes, que permitiu uma expans?o do alcance espacial dessas redes. Mesmo com todas essas mudan?as, a feira ainda permanece como um dos tra?os mais marcantes da din?mica da cidade sendo um l?cus de resist?ncia frente ao surgimento de novas formas de com?rcio e de consumo na cidade (notadamente dos supermercados) e a difus?o de outros vetores da globaliza??o. A feira possui uma import?ncia econ?mica, pois s?o mercados peri?dicos populares destinados ? comercializa??o dos mais diferentes produtos e ao abastecimento da popula??o residente na cidade e nas comunidades rurais de Maca?ba e de outros munic?pios pr?ximos; e sociocultural na medida que a feira ? o lugar onde se expressa com mais for?a a tradi??o popular, o lugar onde se realizam um grande n?mero de atividades paralelas, o lugar dos encontros e reencontros, das conversas, das manifesta??es culturais e art?sticas, da sociabilidade em todas as suas dimens?es

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-19T13:03:28Z No. of bitstreams: 5 isadora.pdf: 1113191 bytes, checksum: d7fa6c19b7906bcd17915b6d1233d2e6 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-20T09:25:04Z (GMT) No. of bitstreams: 5 isadora.pdf: 1113191 bytes, checksum: d7fa6c19b7906bcd17915b6d1233d2e6 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-20T09:25:04Z (GMT). No. of bitstreams: 5 isadora.pdf: 1113191 bytes, checksum: d7fa6c19b7906bcd17915b6d1233d2e6 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Amilases s?o enzimas que atuam no rompimento das liga??es glicos?dicas presentes nas cadeias de amilose e amilopectina. As amilases possuem aplica??es em diversas ?reas tais como: ind?stria de papel e celulose, ind?stria t?xtil, ind?stria de detergentes e produtos de limpeza, ind?stria qu?mica e farmac?utica, na produ??o de vitaminas e antibi?ticos. Embora as amilases sejam encontradas em plantas, animais e micro-organismos, as enzimas microbianas geralmente atendem de maneira satisfat?ria ? demanda industrial. As enzimas microbianas podem ser obtidas por meio de processos fermentativos, podendo ser obtidas tanto por cultivo superficial como por cultivos submersos. O presente trabalho teve por objetivo avaliar a produ??o de enzimas amilol?ticas por fermenta??o submersa utilizando Bacillus amyloliquefaciens ATCC 23350 e coprodutos da cadeia produtiva do biodiesel como substrato. A capacidade da produ??o das enzimas amilol?ticas foi testada utilizando como substratos diferentes coprodutos, sendo esses: torta de maca?ba, torta de dend?, farinha de pupunha, torta de mamona e torta de tremo?o. A torta de maca?ba e farinha de pupunha foram os substratos que demonstraram maior capacidade de produ??o das enzimas amilol?ticas, sendo os coprodutos selecionados para a etapa de otimiza??o da produ??o das enzimas. Diferentes condi??es de processo foram otimizadas com intuito de obter o m?ximo rendimento da produ??o de amilases, atrav?s do emprego de delineamentos experimentais aplicados ? Metodologia de Superf?cie de Resposta. Os processos fermentativos deste trabalho foram realizados ? temperatura de 37?C, 120 rpm de agita??o, utilizando solu??o de sais para suplementa??o do meio. As vari?veis pH, raz?o s?lido-l?quido (S/L) (% m/v) e concentra??o de NH4NO3 (gL-1) foram estudadas. As dosagens das atividades enzim?ticas foram realizadas em tempos de fermenta??o de 12, 24, 36, 48 e 72 horas. A m?xima produ??o das amilases foi alcan?ada com 24 horas de fermenta??o, S/L de 12% e pH 7,0, obtendo valores de 3.393 U.mL-1 com a farinha de pupunha e 196 U.mL-1 com a torta de maca?ba como substratos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012. / ABSTRACT Amylases are enzymes that act in the rupture of glycosidic bonds present in the chains of amylose and amylopectin. Amylases have applications in diverse areas such as pulp and paper industry, textiles, laundry detergents and cleaning products, chemical and pharmaceutical industry, production of vitamins and antibiotics. Although the amylases are found in plants, animals and micro-organisms, microbial enzymes generally meet satisfactorily the industrial demand. The microbial enzymes can be obtained by fermentative procedures, which may be obtained by cultivation both surface and submerged cultivation of micro-organisms. This study aimed to evaluate the production of amylolytic enzymes by submerged fermentation using Bacillus amyloliquefaciens ATCC 23350, and co-products from biodiesel production chain as substrates. The capacity of the production of amylolytic enzymes was tested using different substrates such as co-products, these being: macauba cake, palm kernel cake, peach palm flour, castor bean and lupine cake. The peach palm flour and macauba cake were the substrates which show greater production capacity of amylolytic enzymes, and co-products selected for the optimization step of enzyme production. Different process conditions were optimized with the aim of obtaining the maximum yield of amylases, through the use of experimental designs applied to the Response Surface Methodology. The fermentation process of this work was performed at 37?C, 120 rpm agitation, using salt solution for supplementation of the medium. The pH, liquid-solid ratio (S/L) (% w/v) and concentration of NH4NO3 (gl-1) were studied. The measurements of enzyme activities were carried out in fermentation times of 12, 24, 36, 48 and 72 hours. Maximum production of amylase was achieved with 24 hours of fermentation, S/L of 12% and pH 7.0 to obtain values of 3.393 U.mL-1 with peach palm flour and 196 U.mL-1 with maca?ba cake as substrate.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-19T13:34:45Z No. of bitstreams: 5 hil.pdf: 1837336 bytes, checksum: 915b40a5d9c4387507e76471c6ae2ca7 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-20T11:01:25Z (GMT) No. of bitstreams: 5 hil.pdf: 1837336 bytes, checksum: 915b40a5d9c4387507e76471c6ae2ca7 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-20T11:01:25Z (GMT). No. of bitstreams: 5 hil.pdf: 1837336 bytes, checksum: 915b40a5d9c4387507e76471c6ae2ca7 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-20 / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Para a manuten??o das pr?ticas econ?micas e s?cio-culturais constru?das sobre a explora??o e transforma??o do petr?leo, faz-se necess?rio criar alternativas que n?o rompam de forma estanque com as pr?ticas industriais hoje vigentes. Nesse contexto, o uso de biomassas para a produ??o de combust?veis l?quidos que alimentem motores ? combust?o permite sustentar pr?ticas antigas com novos benef?cios. Dessa forma, a presente disserta??o teve por objetivo avaliar o potencial da torta de maca?ba, um coproduto da ind?stria de ?leos vegetais, como insumo para produ??o de bioetanol. Tal objetivo foi trabalhado atrav?s de estudos de sacarifica??o da torta de maca?ba com posterior processo fermentativo. A biomassa em quest?o foi caracterizada quimicamente, o que indicou a presen?a de aproximadamente 50% de carboidratos, distribu?dos em, 23,16 ? 0,95 % de amido, 11,49 ? 1,08% de celulose, 9,6 ? 0,79% de hemicelulose e 11,48 ? 0,62 % de a??cares sol?veis. Para a primeira interven??o da despolimeriza??o dos polissacar?deos presentes na torta de maca?ba foi realizado um planejamento experimental fatorial 25-1 com 5 fatores e 4 pontos centrais com as seguintes vari?veis: concentra??o de ?cido sulf?rico, tempo de pr?-tratamento ?cido, raz?o s?lido/l?quido, concentra??o de amiloglicosidase e concentra??o de celulase. Na sequ?ncia, o processo de sacarifica??o foi otimizado com o uso de delineamento composto central rotacional 23, com 3 fatores, 4 pontos centrais e 6 pontos axiais, onde foram avaliadas as concentra??es de ?cido sulf?rico, amiloglicosidase e celulase. Um hidrolisado obtido em condi??o otimizada com 92% de efici?ncia foi submetido ? destoxifica??o com carv?o ativado e, em seguida, foram realizados ensaios de fermentabilidade conduzidos como as leveduras Saccharomyces cerevisiae e Pichia stipitis. A levedura S. cerevisiae se mostrou resistente ao hidrolisado n?o destoxificado, apresentando YP/S de 0,49. P. stipitis mostrou-se suscept?vel ao meio n?o destoxificado, mas foi capaz de converter 99% dos a??cares redutores presentes no meio destoxificado. A torta de maca?ba apresentou potencial consider?vel para produ??o de bioetanol. A partir dos dados de bancada ? poss?vel estimar uma produ??o de 104l de etanol por tonelada de torta de maca?ba. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011. / ABSTRACT For the maintenance of economic and socio-cultural practices built on the exploitation and processing of oil it is necessary to create alternatives that do not break so tight with current industrial practices. In this context, the use of biomass to produce liquid fuels that are fed into to combustion engines allows to sustain old practices with new benefits. Thus, this dissertation aimed to evaluate the potential of macaw palm coconut cake, a co-product of vegetable oil industry, as an input for bioethanol production. This goal was worked out through studies of the process of saccharification of macaw palm coconut cake with subsequent fermentation. The biomass in question was characterized chemically, what indicated the presence of approximately 50% of carbohydrates, among which, 23,16 ? 0,95% of starch, 11,49 ? 1,08% of cellulose, 9,6 ? 0,79% of hemicellulose and 11,48 ? 0,62% of soluble sugars. For the first intervention of deconstruction of the polysaccharides present in the macauba cake it was held a 25-1 factorial experimental design with five factors and four central points with the following variables: concentration of sulfuric acid, time of acid pretreatment, solid / liquid ratio, amyloglucosidase and cellulose concentrations. Following, the saccharification process was optimized using central composite rotational design 23, with three factors, four central points and six axial points, whereas the concentrations of sulfuric acid, cellulose and amyloglucosidase were evaluated. A hydrolyzed obtained in optimum condition with 92% efficiency was subjected to detoxification with activated charcoal and then, fermentability assays were carried out with yeasts Saccharomyces cerevisiae and Pichia stipitis. The yeast S. cerevisiae has proved resilient to the non-detoxified hydrolyzate and presented YP/S of 0.49. P. stipitis was found to be susceptible to the non-detoxified medium, but it was able to convert 99% of reducing sugars present in the detoxified medium. The macaw palm coconut cake showed considerable potential for bioethanol production. From the lab bench data it is possible to estimate a production of 104 l of ethanol per ton of macaw palm coconut cake.

Data de aprova??o retirada da vers?o impressa do trabalho. / Incluir a Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) como ag?ncia financiadora. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-12-13T16:15:41Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-01-03T12:17:24Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) / Made available in DSpace on 2018-01-03T12:17:24Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) Previous issue date: 2017 / Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) / A crescente demanda global por combust?veis l?quidos para transporte, gera??o de eletricidade, atividade industrial e produ??o agropecu?ria tem imposto planejamento de a??es direcionadas ao uso de fontes ambientalmente limpas de energia. Os derivados da biomassa s?o alternativas econ?mica e tecnicamente vi?veis aos de origem f?ssil, n?o renov?vel, ora dominantes na matriz energ?tica global. O biodiesel, l?quido formado por uma mistura de ?steres de ?cidos graxos, ? adequado ? opera??o em motores de combust?o interna de ciclo Diesel, em substitui??o ou em complemento ao petrodiesel, ou em outras m?quinas t?rmicas. O prop?sito central do presente trabalho foi o desenvolvimento de um catalisador s?lido economicamente vi?vel, quimicamente eficiente e ambientalmente limpo para a produ??o de biodiesel via processos de transesterifica??o de triacilglicer?is dos ?leos de maca?ba ou de soja, com metanol. Foi preparado o catalisador heterog?neo baseado em iodeto de pot?ssio impregnado em s?lica amorfa (SiO2; derivada de areia da constru??o civil) e misturada a um componente magn?tico sint?tico (maghemita, ?Fe2O3). As estruturas qu?mica, cristalogr?fica e hiperfina essenciais e as propriedades magn?ticas dos materiais precursores e do catalisador s?lido foram investigadas. O teor de ?steres e a composi??o dos biodieseis produzidos foram determinados por cromatografia de fase gasosa acoplada a espectr?metro de massa. A composi??o qu?mica do catalisador, verificada por espectroscopias de energia dispersiva sob feixe de el?trons e por fluoresc?ncia de raios X (FRX), confirmou a ocorr?ncia de Si, Fe, K, e I. As ?reas espec?ficas BET encontradas para os componentes individuais, SiO2, ?Fe2O3 e do catalisador SiO2/KI/?Fe2O3, foram 352, 102, e 19 m2 g-1, respectivamente. A significativa redu??o da ?rea espec?fica do catalisador aponta que os componentes foram efetivamente impregnados no suporte. A morfologia das part?culas visualizadas por microscopias eletr?nicas de varredura e de transmiss?o revela a textura esponjosa do catalisador SiO2/KI/?Fe2O3, similarmente ao suporte de s?lica; o ?xido de ferro magn?tico aparece como material altamente organizado, cristalino, disperso no suporte. Os dados M?ssbauer e da magnetometria do ?xido de ferro magn?tico puro e no catalisador confirmam ser a maghemita, resultando em uma magnetiza??o de satura??o do catalisador de 4,6 emu g-1. O catalisador SiO2/KI/?Fe2O3, usado na transesterifica??o de triacilglicer?is, na propor??o em massa em rela??o ao ?leo da am?ndoa de maca?ba de 4,5% e raz?o molar ?leo:metanol de 1:35, levou ? produ??o de 94,3 massa% de ?steres, ap?s 8 h de rea??o. Foi experimentalmente observado que a maghemita tem comportamento qu?mico-catal?tico sin?rgico com os demais componentes do catalisador. O SiO2/KI/?Fe2O3 foi reutilizado em seis rea??es consecutivas com ?leo de soja, na mesma propor??o do catalisador e raz?o molar ?leo:metanol de 1:35, com rendimentos de 94,5% e tempo reacional de 110 min, para o primeiro ciclo, e de 61,2% e 150 min, para o ?ltimo ciclo. O catalisador, antes e ap?s cada ciclo de reuso, e as al?quotas das rea??es foram analisados por FRX, que mostrou que n?o h? perda significativa dos componentes do catalisador. Os resultados demonstram uma perspectiva tecnol?gica que permite redu??o substantiva do volume de efluentes poluentes e utiliza??o de diferentes mat?rias-primas oleaginosas de alto potencial para a produ??o de biodiesel. / Tese (Doutorado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The global demand for liquid fuels destined to propel automobile motors and for all other types of transport has been growing significantly over the last decades in response to the needs of the population for mobility. These fuels are also necessary for the generation of electricity to support industrial and agricultural activities. However, the principal concern involved in the generation of mechanical work involves the threat that the effluents from burning fuels, particularly those from fossil origin, impart to the environment. Biomass-derived fuels are energetically, economically and environmentally interesting alternatives to the non-renewable fossil fuels, which still dominate the global energy matrix. Biodiesel, a liquid that is composed of a mixture of esters of fatty acids, is mainly suitable for use in Diesel-cycle internal combustion engines, totally replacing or partially complementing petrodiesel. The main purpose of the present work was the development of an economically viable, environmentally clean and chemically efficient solid catalyst for the production of biodiesel via the transesterification reaction of triacylglycerols from maca?ba or soybean oil with methanol. The proposed heterogeneous catalyst was based on potassium iodide-impregnated particles of amorphous silica (SiO2; derived from construction sand) mixed with a synthetic magnetic iron oxide (maghemite, ?Fe2O3). The essential chemical, crystallographic and hyperfine structures and magnetic properties of the starting materials and of the solid catalyst mixture were assessed by physical laboratory techniques. The ester content and the chemical composition of the biodiesel produced were determined by gas chromatography coupled with mass spectrometry. The chemical composition of the catalyst, as determined by electron energy dispersive and X-ray fluorescence (FRX) spectroscopies, confirmed the occurrence of Si, Fe, K, and I. Specific BET surface areas for the SiO2 and ?Fe2O3 components and for the SiO2/KI/?Fe2O3 catalyst were found to be 352; 102 and 19 m2 g-1, respectively. The significant reduction in the specific area of the catalyst indicates that the solid components were intimately mixed and that KI was indeed impregnated on the support. The morphology of the particles, as visualized from the scanning and transmission electron microscopy images, reveals the spongy texture of the SiO2/KI/?Fe2O3 catalyst, which was quite similar to that of the initial silica support. The atomic framework of the magnetic iron oxide appeared to be a highly organized, crystalline nano-material, relatively well dispersed on the silica support. The M?ssbauer and magnetometric data for the pure magnetic iron oxide and for the catalyst confirm that the component is essentially maghemite. The resulting saturation magnetization of the catalyst mixture was 4.6 emu g-1. From the chemical point of view, this maghemite was found to act synergically with the other components of the catalyst and to significantly improve its catalytic activity. The transesterification reaction of triacylglycerols using the SiO2/KI/?Fe2O3 catalyst at a mass ratio corresponding to 4.5 mass% relative to the maca?ba kernel oil and a methanol:oil molar ratio 30:1 yielded 94.3 mass% of esters after 8 h of reaction. The SiO2/KI/?Fe2O3 catalyst was reused for six consecutive transesterification reactions of triacylglicerols in soybean oil employing the same mass proportion of the catalyst and a methanol:oil molar ratio 35:1. A 94.5% yield of esters was obtained after 110 min of reaction in the first cycle, and a 61.2% yield was obtained in the last reaction cycle after 150 min. The compositions of the catalyst before and after each reaction cycle, along with detection of residual chemical elements in the liquid mixture of esters formed, were duly monitored by FRX. There was no significant leaching of the catalyst components during the reactions. These results open a perspective for (i) a substantial reduction in the volume of polluting effluents and (ii) the use bio-oils from native Brazilian flora (maca?ba) as raw materials for the industrial production of biodiesel.