Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2014-12-18T16:36:32Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) alice_lopes_macedo.pdf: 2851693 bytes, checksum: 6e7032a0575fb31a58f4ce49e26fe1a5 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2014-12-18T17:56:03Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) alice_lopes_macedo.pdf: 2851693 bytes, checksum: 6e7032a0575fb31a58f4ce49e26fe1a5 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2014-12-18T18:00:36Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) alice_lopes_macedo.pdf: 2851693 bytes, checksum: 6e7032a0575fb31a58f4ce49e26fe1a5 (MD5) / Made available in DSpace on 2014-12-18T18:00:36Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) alice_lopes_macedo.pdf: 2851693 bytes, checksum: 6e7032a0575fb31a58f4ce49e26fe1a5 (MD5) Previous issue date: 2013 / Os catalisadores heterog?neos desenvolvidos pelo grupo de pesquisa a base de ?cidos de Lewis suportados em diferentes ?xidos inorg?nicos, como por exemplo o ZnCl2/SiO2 e FeSO4/SiO2, tem se mostrado excelentes na esterifica??o de ?cidos graxos livres, por?m ineficazes quando aplicados na transesterifica??o de ?leos vegetais. Este trabalho prop?e o estudo e a s?ntese de um catalisador produzido a partir da substitui??o dos ?cidos de Lewis por ?cido de Bronsted-Lowry, tais como, o ?cido sulf?rico e o ?cido clor?drico. ?leos e gorduras residuais geralmente cont?m um alto ?ndice de ?cidos graxos livres (AGL) e um elevado teor de ?gua em sua constitui??o. Essas subst?ncias dificultam a a??o dos catalisadores b?sicos como NaOH ou KOH que s?o amplamente empregados nestes processos, levando tamb?m a inibi??o de alguns catalisadores a base de ?cidos minerais. A nova mistura catal?tica (H2SO4/SiO2) foi sintetizada a partir de ?cido sulf?rico 10 M imobilizado em s?lica 24 mesh, previamente preparada a partir de areia de constru??o e carbonato de s?dio e caracterizada pelas seguintes t?cnicas anal?ticas: Microscopia Eletr?nica de Varredura, Espectrometria de Dispers?o de Energia, Infravermelho e Termogravimetria. O catalisador foi inicialmente aplicado com ?xito em rea??es de transesterifica??o de ?leos vegetais refinados e de ?leos e gorduras residuais purificados, por?m o grande desafio foi realizar a transesterifica??o de ?leos vegetais de baixa qualidade, os chamados ?leos e gorduras residuais, que al?m de possu?rem em sua constitui??o ?leos vegetais misturados ? gordura animal e ?cidos graxos livres, s?o muitas vezes contaminados por at? 1% de ?gua, em que propor??es acima de 0,5% m/m podem levar a total desativa??o do catalisador. O emprego de s?lica sint?tica 24 mesh na constitui??o do catalisador objetivou aumentar a ?rea de superf?cie, favorecendo o processo de adsor??o de ?gua oriunda da esterifica??o de ?cidos graxos livres e tamb?m a contida nos ?leos e gorduras residuais, evitando uma maior perda da atividade catal?tica por lixivia??o. O rendimento obtido em biodiesel foi acima de 99%, calculado a partir dos dados obtidos por Cromatografia Gasosa acoplada a Espectr?metro de Massa. O catalisador utilizado no processo foi recuperado por lavagem em ?ter et?lico e ativado em estufa 150? C por 3 horas e utilizado em outros processos reacionais. O glicerol obtido como subproduto da transesterifica??o foi utilizado sem pr?via purifica??o na rea??o de catalisa??o com acetona empregando H2SO4/SiO2, formando o cetal 2,2-dimetil-1,3-dioxolano-4-il metanol em 93% de rendimento, o qual foi determinado por CG/EM. Este produto ? caracterizado por sua grande aplica??o como aditivo para combust?veis pela ind?stria automobil?stica. A mistura catal?tica (H2SO4 10M/SiO2) utilizada possui uma capacidade de carga de 1,91x10-3 mols H+/g, ou aproximadamente 9,4% m/m de H2SO4 no catalisador e equivalente a 0,94% m/m de H2SO4 em rela??o ao ?leo vegetal empregado nos diferentes processos reacionais. Essas propor??es se mostraram bem abaixo das propor??es normalmente empregadas em rea??es de transesterifica??o catalisadas por ?cido sulf?rico, que variam de 4 a 5%. O emprego deste catalisador nos processos de transesterifica??o e de catalisa??o, permitiu a sua recupera??o e reutiliza??o por 2 ciclos, sendo que ap?s o ?ltimo ciclo a s?lica resultante foi acidificada novamente, seca e empregada em novos processos catal?ticos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT The heterogeneous catalysts developed by our research group based Lewis acid supported on various inorganic oxides such as: ZnCl2/SiO2 and FeSO4/SiO2, has proved excellent for esterification of free fatty acids, but ineffective when applied in the transesterification vegetable oils. This paper proposes the synthesis and study of a catalyst produced from the Br?nsted-Lowry acids sulfuric acid in replacement of previously employed Lewis acids. Waste oils and fats generally contain a high content of free fatty acids (FFA), as well as a high water content, these substances hinders the action of basic catalysts such as NaOH or KOH which are widely used in these processes, taking also inhibition of some catalysts from the mineral acids. The new catalyst mixture (H2SO4/SiO2) was synthesized from 10 M sulfuric acid immobilized on silica 24 mesh, previously prepared from construction sand and sodium carbonate. Later this material was characterized using the following analytical techniques, Scanning Electron Microscopy, Spectroscopy Dispersion Energy, Infrared and thermogravimetric analysis. Initially, the catalyst was applied in transesterification of vegetable oils and refined oils and waste fats purified. However, the most challenge was to perform the transesterification of vegetable oils of low quality, they called residual oils and fats, over to have in their constution vegetable oils mixed with animal fat and free fatty acid are often contaminated by 1% water, in proportions up to 0.5% w/w can lead to complete deactivation of the catalyst. The use of synthetic silica 24 mesh aimed to increase the surface area, favoring the adsorption of water from the esterification of free fatty acids and also contained in the waste oils and fats, preventing further loss of catalytic activity by leaching. The yield obtained in biodiesel was above 99%, calculated from the data obtained by GC/MS. The catalyst used in the process was recovered by washing using ethyl ether and activated in an oven 150 ?C for 3 hours and used in the process of ketalization of glycerol, as well as in subsequent transesterification reactions. The glycerol obtained as a byproduct of the transesterification was used without purification in the previous reaction of ketalization with acetone employing H2SO4/SiO2 ketalization with acetone forming the ketal 2,2-dimethyl-1 ,3-dioxolan-4-yl methanol in 93% yield, which was determined by GC/MS. This product is characterized by its wide application as a fuel additive for the automotive industry. The catalytic mixture (H2SO410 M/SiO2) used has a capacity of 1.91 x10-3mol H+/g, or about 9,4% w/w of H2SO4 in the catalyst, equivalent to 0.94% w/w of H2SO4 in compared to vegetable oil employed in the different reaction processes, these proportions were below the proportions normally used in transesterification reactions catalyzed by sulfuric acid ranging from 4 to 5%. The use of this catalyst in processes of transesterification and ketalization allowed the recovery and reuse during two cycles. After the last cycle, the resulting silica was acidified, dried and used in another catalytic process

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-11-27T15:27:52Z No. of bitstreams: 1 GiceliaRodrigues_TESE.pdf: 4017865 bytes, checksum: c0fa528988ec3e75c837780c20f66c73 (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2015-11-30T23:51:12Z (GMT) No. of bitstreams: 1 GiceliaRodrigues_TESE.pdf: 4017865 bytes, checksum: c0fa528988ec3e75c837780c20f66c73 (MD5) / Made available in DSpace on 2015-11-30T23:51:12Z (GMT). No. of bitstreams: 1 GiceliaRodrigues_TESE.pdf: 4017865 bytes, checksum: c0fa528988ec3e75c837780c20f66c73 (MD5) Previous issue date: 2014-08-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Atualmente, o Brasil conta com grande potencial e boas perspectivas futuras para a manuten??o e amplia??o de sua matriz energ?tica. S?o exemplos de alternativas para o futuro, os petr?leos oriundos do pr?-sal, energias e?licas, hidrel?tricas, nuclear, al?m dos biocombust?veis. O est?mulo ? produ??o e ao consumo de bicombust?vel favorece mundialmente a pol?tica de preserva??o ao meio ambiente, contribuindo na redu??o dos gases, poluentes, causadores do efeito estufa e redu??o das altera??es clim?ticas. A presen?a de catalisadores nos processos de produ??o de bicombust?veis desempenha um importante papel na melhoria da rotas de produ??o, tais como: taxa de rea??o, rendimento e seletividade de produtos e co-produtos de alto valor agregado. A tend?ncia atual das pesquisas nesse campo foca no aprimoramento desses processos com o uso de catalisadores heterog?neos, visto que catalisadores heterog?neos apresentam vantagens significativas, tais como: menor contamina??o dos produtos, facilidade de separa??o do catalisador do meio reacional, possibilidade de reaproveitamento do catalisador, diminui??o dos problemas de corros?o. Portanto, pesquisas est?o sendo desenvolvidas para obten??o de materiais mesoporosos, que s?o catalisadores heterog?neos, devido ao fato de que esses materiais apresentam facilidade de s?ntese e s?o economicamente vi?veis, apresentam poros relativamente grandes que facilitam a acessibilidade de ?cidos graxos no interior das part?culas, minimizando resist?ncias ao transporte de massa. Ap?s montada matriz experimental para a s?ntese do Al-SBA-15, foi realizado a s?ntese hidrot?rmica do Al-SBA-15 com diferentes raz?es de Si/Al variando as quantidades estequiom?tricas dos materiais precursores.Os testes catal?ticos foram a rea??o de transesterifica??o utilizando como m?tria-prima o ?leo de coco bruto e a pir?lise. As rea??es de transesterifica??o foram realizadas em um reator Parr de a?o inoxid?vel, modelo 4523, equipado com agitador mec?nico, indicadores de temperatura e press?o. O tratamento cin?tico referente aos dados da pir?lise do ?leo de coco puro e do ?leo de coco com AlSBA-15, realizou-se por meio da utiliza??o de curvas termogravim?tricas (TG) obtidas em uma termobalan?a modelo TGA/SDT Q600 da TA instruments, nas seguintes taxas de aquecimento: 5,10 e 20?C min-1. O ?leo de coco bruto apresentou com uma mat?ria-prima apropriada para obten??o do biodiesel via rota et?lica e o catalisador sintetizado com as condi??es experimentais I, apresentou as melhores condi??es para a s?ntese de biodiesel. Os aspectos visuais e as caracter?sticas f?sico-qu?micas dos produtos da rea??o, mostram que o catalisador AlSBA-15 favoreceu a rea??o. De acordo com as analises f?sico-qu?micas a ordem de estabilidade oxidativa do produto da rea??o de transesterifica??o foi: 1500?C +AlSBA-15 > 100?C> 100?C + AlSBA-15> 200?C + AlSBA-15. / Stimulus encouraging the production and consumption of biodiesel favors the policy of pre-serving the environment, contributing to the reduction of greenhouse gas reducing climate change. The current trend of research in this field focuses on improving these processes with the use of heterogeneous catalysts, seeing has significant advantages such as: low contamination of products, ease of separation of the catalyst from the reaction medium, possibili-ty of reuse of the catalyst, decreased corrosion problems. The objective of this research was to optimize the synthesis of AlSBA-15 for the production of biodiesel through transesterification process via ethyl route. For the optimization of hydrothermal synthesis of type AlSBA-15 catalyst has assembled a 23 factorial experimental matrix with eleven trials. The stoichiometric amounts of starting materials were varied according to different ratios Si / Al which is a factor in the experimental design, in addition to the time and temperature of aging of the synthesis gel. The material showed the best results of characterization (SBET = 591.7 (m2 / g), Vp = 0.83 (cm3 / g), Dp = 5.59 (nm), w = 6.48 (nm) was synthesized at 100 ? C for 24 hours, with a ratio Si / Al = 10.This material was applied as a heterogeneous catalyst in the reaction of ethyl transesterification as raw coconut oil in natura. Coconut oil presented suitable for obtaining biodiesel via ethyl route.The visual aspects and physical-chemical characteristics of the reaction products show that AlSBA-15 catalyst favored the reaction. According to physical-chemical analysis the order of oxidative stability of the product of the transesterification reaction was: catalytic reaction at 1500 ? C> non-catalytic reaction at 100 ? C> 100 ? C catalytic> catalytic reaction at 200 ? C Reaction. The results of oxidative stability and kinematic viscosity shows that the biodiesel produced in the catalytic sandblasting held at 150 ? C which was maintained within the ABNT NBR 7148, ABNT NBR 10441 and EN 14112.

Made available in DSpace on 2014-12-17T14:58:20Z (GMT). No. of bitstreams: 1 LuandaKOR_DISSERT.pdf: 4300124 bytes, checksum: 469607cbcb40b12cb19598ea2781bdff (MD5) Previous issue date: 2013-07-24 / The lubricants found in the market are of mineral or synthetic origin and harm to humans and the environment, mainly due to their improper discard. Therefore industries are seeking to develop products that cause less environmental impact, so to decrease mainly, operator aggression the Cutting Fluids became an emulsion of oil / water or water / oil. However, the emulsion was not considered the most suitable solution for environmental question, therefore the search for biodegradable lubricants and which no are toxic continues and so vegetable oils are seen, again, as a basis for the production of lubricants. The biggest problem with these oils is their oxidative instability that is intensified when working at high temperatures. The process transesterification decreases the oxidation, however changes some physical and chemical properties. Therefore soybean oil after the transesterification process was subjected to tests of density, dynamic viscosity, kinematic viscosity which is calculated from two parameters mentioned, flash point and acidity. Besides the physico-chemical test the soybean oil was subjected to a dynamic test in a tribometer adapted from a table vise, whose induced wear was the adhesive and ultimately was used as cutting fluid in a process of turning in two different materials, steel 1045 and cast iron. This latter test presented results below the mineral cutting fluid which it was compared in all tests, already in other experiments the result was satisfactory and other experiments not, so that chemical additives can be added to the oil analyzed to try equate all parameters and so formulate a biolubrificante not toxic to apply in machining processes of metalworking industry / Os lubrificantes encontrados no mercado s?o de origem mineral ou sint?tico e agridem ao homem e ao meio ambiente, principalmente, devido ao seu descarte inadequado, por isso as ind?strias est?o buscando desenvolver produtos que causem um menor impacto ambiental. Para diminuir a agress?o ao operador, principalmente, os Fluidos de Corte passaram a formar uma emuls?o ?leo/?gua ou ?gua/?leo. No entanto a emuls?o n?o foi tida como a solu??o mais adequada para a quest?o ambiental, portanto a busca por lubrificantes biodegrad?veis e que n?o sejam t?xicos continua e assim os ?leos vegetais est?o sendo vistos, novamente, como base para a produ??o de lubrificantes. O maior problema desses ?leos ? sua instabilidade oxidativa que ? intensificada ao trabalhar em altas temperaturas. O processo de transesterifica??o diminui a oxida??o, no entanto altera algumas propriedades f?sico-qu?micas. Portanto o ?leo de Soja ap?s o processo de transesterifica??o foi submetido aos ensaios de densidade, viscosidade din?mica (cuja viscosidade cinem?tica foi calculada a partir dos dois par?metros citados); ponto de fulgor e acidez. Al?m dos ensaios f?sico-qu?micos, o ?ster de soja foi submetido a um ensaio din?mico em um trib?metro adaptado de um torno de bancada cujo desgaste induzido foi o adesivo e por ?ltimo foi usado como fluido de corte em um processo de torneamento em dois materiais distintos, A?o1045 e Ferro Fundido. Esse ?ltimo ensaio apresentou resultados inferiores ao fluido de corte mineral o qual foi comparado em todos os ensaios, j? nos outros ensaios alguns o resultado era satisfat?rio em outros n?o de modo que aditivos qu?micos podem ser adicionados ao ?leo analisado para tentar equacionar todos os par?metros e assim formular um biolubrificante n?o t?xico para aplicar nos processos de usinagem da ind?stria metal-mec?nica

Made available in DSpace on 2014-12-17T15:01:35Z (GMT). No. of bitstreams: 1 ZanielSDP_DISSERT.pdf: 2717599 bytes, checksum: 57e9c7752ad1f265d12ad2b68b546c90 (MD5) Previous issue date: 2014-04-04 / Petr?leo Brasileiro SA - PETROBRAS / Microalgae are microscopic photosynthetic organisms that grow rapidly and in different environmental conditions due to their simple cellular structure. The cultivation of microalgae is a biological system capable of storing solar energy through the production of organic compounds via photosynthesis, and these species presents growth faster than land plants, enabling higher biomass yield. Thus, it is understood that the cultivation of these photosynthetic mechanisms is part of a relevant proposal, since, when compared to other oil producing raw materials, they have a significantly higher productivity, thus being a raw material able to complete the current demand by biodiesel . The overall aim of the thesis was to obtain biofuel via transesterification process of bio oil from the microalgae Isochrysis galbana. The specific objective was to estimate the use of a photobioreactor at the laboratory level, for the experiments of microalgae growth; evaluating the characteristics of biodiesel from microalgae produced by in situ transesterification process; studying a new route for disinfection of microalgae cultivation, through the use of the chemical agent sodium hypochlorite. The introduction of this new method allowed obtaining the kinetics of the photobioreactor for cultivation, besides getting the biomass needed for processing and analysis of experiments in obtaining biodiesel. The research showed acceptable results for the characteristics observed in the bio oil obtained, which fell within the standards of ANP Resolution No. 14, dated 11.5.2012 - 18.5.2012. Furthermore, it was demonstrated that the photobioreactor designed meet expectations about study culture growth and has contributed largely to the development of the chosen species of microalgae. Thus, it can be seen that the microalgae Isochrysis galbana showed a species with potential for biodiesel production / As microalgas s?o organismos microsc?picos fotossintetizantes que crescem rapidamente e em diferentes condi??es ambientais devido a sua simples estrutura celular. O cultivo de microalgas ? um sistema biol?gico capaz de armazenar energia solar, atrav?s da produ??o de compostos org?nicos via processo fotossint?tico, sendo que a maioria das esp?cies apresenta crescimento mais r?pido que as plantas terrestres, possibilitando maior rendimento de biomassa. Assim, compreende-se que o cultivo desses mecanismos fotossintetizantes se insere numa proposta relevante, uma vez que, quando comparados a outras mat?rias primas produtoras de ?leo, apresentam uma produtividade significativamente maior, sendo, portanto, uma mat?ria-prima capaz de completar a demanda atual de biodiesel. O objetivo geral da disserta??o foi a obten??o do biocombust?vel via processo de transesterifica??o do bio-?leo obtido a partir da microalga Isochrysis galbana. O estudo ainda teve por objetivos espec?ficos estimar o uso de um fotobiorreator em n?vel laboratorial, para realiza??o de experimentos de crescimento de microalgas; avaliar as caracter?sticas do biodiesel produzido por processo de transesterifica??o in situ da microalga; estudar uma nova rota para desinfec??o deste meio de cultura, por meio do uso do agente qu?mico hipoclorito de s?dio. Com a introdu??o deste novo m?todo foi poss?vel obter a cin?tica de crescimento do cultivo para o fotobiorreator, al?m de obter a biomassa necess?ria para transforma??o nos experimentos de an?lise e obten??o do biodiesel. A pesquisa apontou resultados aceit?veis para as caracter?sticas verificadas no bio-?leo obtido, o qual se enquadrou nos padr?es da resolu??o ANP N?14, de 11.5.2012 DOU 18.5.2012. Al?m disso, demonstrou-se que o fotobiorreator projetado atendeu ?s expectativas no que concerne ao crescimento do cultivo estudado e contribuiu amplamente para o desenvolvimento da esp?cie de microalga escolhida. Dessa maneira, pode-se constatar que a microalga Isochrysis galbana se mostrou uma esp?cie com potencial para a produ??o de biodiesel

Made available in DSpace on 2014-12-17T15:41:39Z (GMT). No. of bitstreams: 1 MirnaFF.pdf: 726469 bytes, checksum: 081aa47437617ba8013fcd1faab3c2f1 (MD5) Previous issue date: 2006-12-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work biodiesel was gotten through the transesterification reaction using the oil of castor as source of triglycerides and using the methylic route for obtaining of esters. For the characterization of biodiesel and its mixtures with mineral diesel oil, physical chemical parameters and several analytical techniques had been used, as well as: gas chromatography (GC), nuclear magnetic resonance of proton (1H NMR), infrared spectroscopy (IR) and thermal analysis. The chromatography confirmed the complete reaction of esters in biodiesel presenting a 97,08% conversion. The 1H - NMR presented singlet in 3,6 ppm corresponding to the hydrogen of the group ester RCOO CH3. The infrared presented a strong band in 1741 cm-1 referring to stretching C=O of ester and an average band in 1175 cm-1 referring C O deformation. With the data of thermal analysis it was possible to observe the thermal and oxidative stability of the samples changing the atmospheres of synthetic air and nitrogen, where stages of the thermal decomposition had been verified and had been attributed to the volatilization and/or decomposition of the triacylglycerides. The thermal degradation of the samples was carried through 150 and 210?C during 1, 12, 24 and 48 hours and was observed change in the thermogravimetric profile, therefore an increase in the number of stages of the thermal decomposition also occurred indicating characteristic intermediate composites of polymerization, being this confirmed through the rheological study that presented brusque increase of viscosity. The kinetic study showed that the activation energy has the following order: biodiesel > mineral diesel oil > mixtures biodiesel/diesel / Neste trabalho o biodiesel foi obtido atrav?s da rea??o de transesterifica??o usando o ?leo de mamona como fonte de triglicer?deos e utilizando a rota met?lica para obten??o dos ?steres. Para a caracteriza??o do biodiesel e das suas misturas com o diesel mineral foram utilizados par?metros f?sico qu?micos e v?rias t?cnicas anal?ticas, como: cromatografia em fase gasosa (CG), resson?ncia magn?tica nuclear de pr?tons (RMN 1H), espectrofotometria na regi?o do infravermelho (IV) e an?lise t?rmica. A cromatografia confirmou a rea??o completa dos ?steres em biodiesel apresentando uma convers?o de 97,08%. O RMN 1H apresentou o singlete em 3,6 ppm correspondente aos hidrog?nios do grupo ?ster RCOO CH3. J? o infravermelho apresentou uma banda forte em 1741 cm-1 referente ao estiramento C=O do ?ster e uma banda m?dia a 1175 cm-1 referente a deforma??o C-O. Com os dados de an?lise t?rmica foi poss?vel observar a estabilidade t?rmica e oxidativa das amostras variando as atmosferas de ar sint?tico e nitrog?nio, onde foram verificadas etapas da decomposi??o t?rmica que foram atribu?das ? volatiliza??o e/ou decomposi??o dos triacilglicer?deos. A degrada??o t?rmica das amostras foi realizada a 150 e 210?C por 1, 12, 24 e 48 horas e foi observado mudan?a no perfil termogravim?trico, pois ocorreu um aumento no n?mero de etapas da decomposi??o t?rmica indicando compostos intermedi?rios caracter?sticos de polimeriza??o, sendo este fato tamb?m confirmado atrav?s do estudo reol?gico que apresentou aumento brusco de viscosidade. O estudo cin?tico realizado mostrou que a energia de ativa??o tem a seguinte ordem: biodiesel do ?leo de mamona > diesel > misturas biodiesel/diesel mineral

Made available in DSpace on 2014-12-17T15:42:05Z (GMT). No. of bitstreams: 1 AndersonFG_DISSERT.pdf: 1945456 bytes, checksum: 6842614cc74ff1e826a7c5a7abfca129 (MD5) Previous issue date: 2013-06-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The cultivation of microalgae biomass in order to produce biodiesel arises as an extremely promising aspect, in that the microalgae culture includes short cycle of reproduction, smaller areas for planting and residual biomass rich in protein content. The present dissertation evaluates the performance and features, through spectrometry in the region of infrared with transformed Fourier (FTIR) and spectrometry in the region of UVvisible (UV-Vis), of the extracted lipid material (LM) using different techniques of cell wall disruption (mechanical agitation at low and at high spin and agitation associated with cavitation). The technique of gas chromatography (GC) brought to light the success of alkaline transesterification in the conversion of oil into methyl monoesters (MME), which was also analyzed by spectroscopic techniques (FTIR, proton magnetic resonance (1H NMR) and carbon (13C NMR). Through thermogravimetric analysis (TGA) were analyzed the lipid material (LM), biodiesel and the microalgae biomass. The method which provided the best results concerning the efficiency in extraction of the LP of Monoraphidium sp. (12,51%) was by mechanical agitation at high spin (14 000 rpm), for 2 hours being the ideal time, as shown by the t test. The spectroscopic techniques (1H NMR, 13C NMR and FTIR) confirmed that the structure of methyl monoesters and the chromatographic data (CG) revealed a high content of saturated fatty acid esters (about 70%) being the major constituent eicosanoic acid (33,7%), which justifies the high thermal stability of microalgae biodiesel. The TGA also ratified the conversion rate (96%) of LM into MME, pointing out the quantitative results compatible with the values obtained through GC (about 98%) and confirmed the efficiency of the extraction methods used, showing that may be a good technique to confirm the extraction of these materials. The content of LM microalgae obtained (12,51%) indicates good potential for using such material as a raw material for biodiesel production, when compared to oil content which can be obtained from traditional oil for this use, since the productivity of microalgae per hectare is much larger and requires an extremely reduced period to renew its cultivation / O cultivo de biomassa microalgal visando ? produ??o de biodiesel desponta como uma vertente extremamente promissora, pois a cultura de microalgas inclui curto ciclo de reprodu??o, ?reas menores para o plantio e biomassa residual rica em conte?do proteico. O presente trabalho avalia o rendimento e caracter?sticas, por espectofometrias na regi?o do infravermelho com transformada de Fourier (FTIR) e do UV-visivel (UV-V?s), do material lip?dico (ML) extra?do empregando-se diferentes t?cnicas de rompimento da parede celular (agita??o mec?nica em baixa e em alta rota??o e agita??o associada ? cavita??o). A t?cnica de cromatografia em fase gasosa (CG) evidenciou o ?xito da transesterifica??o alcalina na convers?o do ?leo em mono?steres met?licos (MEM), que tamb?m foram analisados por t?cnicas espectrosc?picas (FTIR, resson?ncia magn?tica de pr?ton (RMN 1H) e carbono (RMN 13C). Atrav?s da termogravimetria (TG) foram analisados o material lip?dico (ML), o biodiesel e a biomassa microalgal. O m?todo que forneceu os melhores resultados quanto ? efic?cia na extra??o do ML da Monoraphidium sp. (12,51%) foi ? agita??o mec?nica sob alta rota??o (14 000 rpm) sendo de 2 horas o tempo ideal, como mostrado pelo teste t. As t?cnicas espectrosc?picas (RMN 1H, RMN 13C e FTIR) confirmaram a estrutura dos mono?steres met?licos e os dados cromatogr?ficos (CG) revelaram alto teor de ?steres de ?cidos graxos saturados (aproximadamente 70%), sendo o constituinte majorit?rio o ?cido eicosan?ico (33,7 %), fato que justifica a elevada estabilidade t?rmica do biodiesel microalgal. A TG tamb?m ratificou a taxa convers?o (96%) do ML em MEM, mostrando resultados quantitativos compat?veis com os valores obtidos pela CG (aproximadamente 98%) e confirmou a efici?ncia dos m?todos de extra??o usados, mostrando que pode ser uma boa t?cnica para confirmar a extra??o destes materiais. O teor obtido de ML microalgal (12,51 %) indica um bom potencial de uso deste material como mat?ria prima na produ??o de biodiesel, quando comparado ao teor de ?leo que pode ser obtido de oleaginosas tradicionais para este uso, j? que a produtividade das microalgas por hectare ? muito maior e exige um per?odo extremamente reduzido para renova??o de seu cultivo

Made available in DSpace on 2014-12-17T15:42:20Z (GMT). No. of bitstreams: 1 HellydaKTAS_DISSERT.pdf: 3306619 bytes, checksum: 6db9524bb03341082d99032fc6dfcf10 (MD5) Previous issue date: 2011-03-11 / Biodiesel is a fuel made up by mono-alkyl-esters of long chain fatty acids, derived from vegetable oils or animal fat. This fuel can be used in compression ignition engines for automotive propulsion or energy generation, as a partial or total substitute of fossil diesel fuel. Biodiesel can be processed from different mechanisms. Transesterification is the most common process for obtaining biodiesel, in which an ester compound reacts with an alcohol to form a new ester and a new alcohol. These reactions are normally catalyzed by the addition of an acid or a base. Initially sunflower, castor and soybean oil physicochemical properties are determined according to standard test methods, to evaluate if they had favorable conditions for use as raw material in the transesterification reaction. Sunflower, castor and soybean biodiesel were obtained by the methylic transesterification route in the presence of KOH and presented a yield above 93% m/m. The sunflower/castor and soybean/castor blends were studied with the aim of evaluating the thermal and oxidative stability of the biofuels. The biodiesel and blends were characterized by acid value, iodine value, density, flash point, sulfur content, and content of methanol and esters by gas chromatography (GC). Also studies of thermal and oxidative stability by Thermogravimetry (TG), Differential Scanning Calorimetry High Pressure (P-DSC) and dynamic method exothermic and Rancimat were carried out. Biodiesel sunflower and soybean are presented according to the specifications established by the Resolution ANP no 7/2008. Biodiesel from castor oil, as expected, showed a high density and kinematic viscosity. For the blends studied, the concentration of castor biodiesel to increased the density, kinematic viscosity and flash point. The addition of castor biodiesel as antioxidant in sunflower and soybean biodiesels is promising, for a significant improvement in resistance to autoxidation and therefore on its oxidative stability. The blends showed that compliance with the requirements of the ANP have been included in the range of 20-40%. This form may be used as a partial substitute of fossil diesel / Biodiesel ? um combust?vel constitu?do por mono-alquil-?steres de ?cidos graxos de cadeias longas, derivado de ?leos vegetais ou gordura animal. Este combust?vel pode ser utilizado em motores de igni??o por compress?o para a propuls?o de ve?culos autom?veis ou gera??o de energia, como um substituto parcial ou total de diesel f?ssil combust?vel. O biodiesel pode ser processado a partir de diferentes mecanismos. A transesterifica??o ? o processo mais comum para obten??o do biodiesel, em que um ?ster reage com um ?lcool para formar outro ?ster e um novo ?lcool. Essas rea??es s?o normalmente catalisadas pela adi??o de um ?cido ou uma base. Inicialmente, foram determinadas as propriedades f?sico-qu?micas dos ?leos de girassol, mamona e soja de acordo com as especifica??es de metodologias de teste padronizadas, com o intuito de avaliar se os mesmos possu?am condi??es favor?veis para serem utilizados como mat?ria-prima na rea??o de transesterifica??o. O biodiesel desses ?leos foi obtido atrav?s da rea??o de transesterifica??o pela rota met?lica, fazendo uso de KOH no preparo do catalisador (met?xido de pot?ssio). O rendimento das rea??es de transesterifica??o foi acima de 93% m/m. Os biocombust?veis e as blends foram caracterizados pelos ?ndices de acidez e iodo, ponto de fulgor, pela massa espec?fica, pelos teores de enxofre, metanol e ?steres. As estabilidades t?rmica e oxidativa foram avaliadas atrav?s da Termogravimetria (TG), da Calorimetria Explorat?ria Diferencial sob Press?o (P-DSC) pelos m?todos din?mico e isot?rmico, e do Rancimat. As amostras de biodiesel de girassol e soja apresentaram conformidade com as especifica??es estabelecidas pela Resolu??o ANP no 7/2008. O biodiesel de mamona, como esperado, apresentou elevadas massa espec?fica e viscosidade cinem?tica. A adi??o do biodiesel de mamona como antioxidante ao biodiesel de girassol e de soja ? promissora, pois promoveu uma melhora significativa na resist?ncia ? auto-oxida??o e, por conseguinte, na estabilidade oxidativa de ambos. Para as blends estudadas, o aumento da concentra??o de biodiesel de mamona contribuiu para um aumento da massa espec?fica, viscosidade cinem?tica e ponto de fulgor. As blends que apresentaram conformidade ?s exig?ncias da ANP foram ?quelas compreendidas na faixa de 20-40% de biodiesel de mamona adicionado, o que as tornam candidatas ? substituta do diesel f?ssil

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-12T18:27:28Z No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-13T20:12:54Z (GMT) No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) / Made available in DSpace on 2017-12-13T20:12:54Z (GMT). No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) Previous issue date: 2017-09-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / H? d?cadas que a produ??o de combust?veis alternativos visando ? substitui??o do petr?leo e de seus derivados tem despertado o interesse de muitos pesquisadores em todo o planeta. Biodiesel ? uma alternativa renov?vel, o qual pode ser produzido a partir de ?leos residuais, gorduras animais e ?leos vegetais atrav?s do processo de transesterifica??o heterog?nea utilizando ?lcoois. Nesse contexto, catalisadores heterog?neos t?m se apresentado como potencial na produ??o de biodiesel em raz?o da possibilidade do seu reuso e por ser um processo mais limpo e eficiente. No presente trabalho, carv?o ativado obtido da pir?lise do lodo de esgoto (C.A), Mo2C, Mo2C/C.A e Ni (20%)-Mo2C/C.A foram avaliados no processo de transesterifica??o met?lica do ?leo de soja refinado visando ? produ??o de biodiesel. O carv?o do lodo foi tratado com o KOH no sentido de abrir os poros e promover maior ?rea especifica de contato, seguido de ativa??o f?sica. Os catalisadores a base de molibd?nio foram sintetizados a partir da rea??o g?s-s?lido utilizando como precursor heptamolibdato de am?nio e uma mistura de CH4/H2. Todos os materiais foram caracterizados utilizando as an?lises de TG, DRX, FRX, MEV, B.E.T e granulometria a laser. O processo de transesterifica??o foi avaliado em um reator de mistura constitu?do de um sistema de aquecimento e refluxo da fase alco?lica. Em temperatura constante de 65 oC, as condi??es operacionais estudadas para a rea??o foram: a natureza e concentra??o m?ssica (1 a 5%) do catalisador em rela??o ? massa do ?leo, a raz?o molar ?leo/?lcool (1/6 a 1/18), o pH do meio reacional (2,0 a 8,5), o tempo de rea??o (3 e 5 h) e a velocidade de agita??o da fase l?quida (450 e 600 rpm). Para todas as condi??es e demais catalisadores, o biodiesel foi produzido. A convers?o m?xima do ?leo de soja encontrada foi de 27,34%, no estudo cin?tico, para o catalisador Mo2C/C.A nas condi??es operacionais de 1% de catalisador, 6 h de rea??o, raz?o molar ?leo/?lcool de 1/12 e pH = 5. Na an?lise de caracteriza??o de uma amostra de biodiesel produzido o ponto de fulgor apresentou valor de 141 ?C, o qual est? acima do m?nimo especificado pela ANP. Um modelo cin?tico pseudo homog?neo foi utilizado, para o catalisador Mo2C/C.A atrav?s do qual foi mostrado que os resultados experimentais se ajustaram satisfatoriamente a uma cin?tica de 1? ordem, cuja constante cin?tica de velocidade teve como valor 0,0009 min-1. / For decades, the production of environment-friendly fuels, as alternative power sources for oil, has gained attention and interest of researchers worldwide. Biodiesel is a renewable alternative fuel that can be obtained from residual oils, animal fat and vegetable oils through heterogeneous transesterification reaction using alcohol. In this context, heterogeneous catalyst present potential for biodiesel production as they can be regenerated and provide a cleaner and more efficient process. In this work, several molybdenum carbide catalysts were tested for the transesterification reaction of soybean oil with methanol towards producing biodiesel. These catalysts were pure Mo2C, Mo2C supported over activated carbon (A.C), pure A.C and bimetallic Ni (20%)-Mo2C/A.C being this support produced from sewage sludge pyrolysis. The pyrolysis product was treated with KOH, in order to increase its porosity and promote a larger specific surface area, and later physically activated. Gas solid reaction with CH4 and H2 atmosphere was used to produce the studied molybdenum derived catalysts, and ammonium molybdate was used as molybdenum source in all cases. All catalysts were characterized in a TG, XDR, XFR, SEM, B.E.T and laser particle size analysis basis. Their activity towards transesterification reaction was evaluated by using a mixing reactor with temperature control and alcohol reflux at 65 ?C. The parameters that were manipulated for this experimental evaluation were: type and mass concentration of the catalyst (1 to 5%), oil/alcohol ratio (1/6 to 1/18), pH (2.0 to 8.5), reaction time (3 and 5h) and liquid phase agitation speed (450 and 600 rpm). For all conditions and other catalysts, biodiesel was produced. The maximum conversion found was 27.34% for the Mo2C/A.C catalyst under the operating conditions of 1% catalyst, 6 h reaction, oil/alcohol ration of 1/12 and pH = 5. In the characterization analysis of a sample of biodiesel produced the flash point presented a value of 141 ?C, which is above the minimum specified by the ANP. A pseudo homogeneous kinetics model was used, and experimental data presented agreement with a 1st order reaction with speed rate constant of 0,0009 min-1.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-12T18:27:29Z No. of bitstreams: 1 SauloHenriqueGomesDeAzevedo_TESE.pdf: 2820544 bytes, checksum: f1294c696450b1d2d679c0c9eac313f7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-13T20:40:34Z (GMT) No. of bitstreams: 1 SauloHenriqueGomesDeAzevedo_TESE.pdf: 2820544 bytes, checksum: f1294c696450b1d2d679c0c9eac313f7 (MD5) / Made available in DSpace on 2017-12-13T20:40:34Z (GMT). No. of bitstreams: 1 SauloHenriqueGomesDeAzevedo_TESE.pdf: 2820544 bytes, checksum: f1294c696450b1d2d679c0c9eac313f7 (MD5) Previous issue date: 2017-09-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / No contexto energ?tico mundial, o biodiesel tem despontado como uma importante fonte de energia renov?vel, sobretudo devido ? facilidade de produ??o do mesmo e ? variedade de mat?ria-prima dispon?vel mundialmente. Especificamente no Brasil, a ind?stria de biodiesel tem apresentado importante crescimento de produ??o, tendo em vista as leis federais que obrigam a mistura do B100 (biodiesel) ao diesel f?ssil. Diante da import?ncia desta ind?stria para o Brasil, este trabalho buscou avaliar o potencial do ?leo de sementes de algod?o para a produ??o de biodiesel a partir de tr?s t?cnicas: transesterifica??o, utilizando etanol, interesterifica??o, usando acetato de metila, e interesterifica??o, com acetato de metila e adi??o de solu??o aquosa de ?cido ac?tico. As rea??es ocorreram em condi??es supercr?ticas, em reator tubular de fluxo cont?nuo com volume de 15 mL. O rendimento m?ximo obtido pela transesterifica??o foi de 75,05%, na press?o de 150 e 200 bar, 375 ?C, raz?o molar ?leo/etanol 1:40, e tempos espaciais 40 min (150 bar) e 30 min (200 bar). J? na rota utilizando acetato de metila, o maior rendimento foi de 99,51% (?steres met?licos de ?cidos graxos + triacetina), obtido em 35 min, raz?o m?ssica ?leo/acetato de metila 1:3, press?o 200 bar e 350 ?C, utilizando 20%, em massa, de solu??o aquosa de ?cido ac?tico com concentra??o de 26%. Foram observados elevados valores de decomposi??o do biodiesel, em ambas as rotas, devido ?s altas concentra??es de triglicer?deos poliinsaturados no ?leo e ?s severas condi??es do processo. / In the global energy context, biodiesel has emerged as an important source of renewable energy, mainly due to its ease of production and the variety of raw material available worldwide. Specifically in Brazil, the biodiesel industry has shown significant production growth, due to the federal laws that require the mixing of B100 (biodiesel) with fossil diesel. Considering the importance of this industry to Brazil, this work sought to evaluate the potential of cotton seed oil for the production of biodiesel from three techniques: transesterification using ethanol, interesterification using methyl acetate and interesterification with methyl acetate and addition of aqueous acetic acid solution. The reactions occurred under supercritical conditions in a continuous flow tubular reactor with a volume of 15 mL. The maximum yield obtained by transesterification was 75.05%, at 150 and 200 bar pressure, 375 ?C, 1:40 oil/ethanol molar ratio, and spatial times 40 min (150 bar) and 30 min (200 bar). In the other method, using methyl acetate, the highest yield was 99.51% (methyl esters of fatty acids+ triacetin) obtained in 35 min, oil/methyl acetate ratio 1:3, pressure 200 bar and 350 ?C, using 20%, by mass, of aqueous acetic acid solution with a concentration of 26%. High values of biodiesel decomposition were observed in both routes due to the high concentrations of polyunsaturated triglycerides in the oil and the severe process conditions.

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.