Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-12T14:40:37Z No. of bitstreams: 1 AldoMiroDeMedeiros_DISSERT.pdf: 1734971 bytes, checksum: 889f757c4cc2a5e3660c134b7cf6a984 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-18T14:31:25Z (GMT) No. of bitstreams: 1 AldoMiroDeMedeiros_DISSERT.pdf: 1734971 bytes, checksum: 889f757c4cc2a5e3660c134b7cf6a984 (MD5) / Made available in DSpace on 2017-01-18T14:31:25Z (GMT). No. of bitstreams: 1 AldoMiroDeMedeiros_DISSERT.pdf: 1734971 bytes, checksum: 889f757c4cc2a5e3660c134b7cf6a984 (MD5) Previous issue date: 2016-07-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / No presente trabalho foi realizado um estudo do processo de interesterifica??o do ?leo de algod?o com acetato de metila, usando met?xido de pot?ssio como catalisador, na presen?a de ondas ultrass?nicas. Com o objetivo de melhor compreender as vari?veis importantes do processo, foi utilizado um planejamento experimental do tipo estrela, uma metodologia de superf?cie de resposta e t?cnicas estat?sticas. Os experimentos foram realizadas com raz?o molar variando de 1:8 a 1:24, percentagem de catalisador de 0,1 a 1,3% em peso, amplitude do bico ultrass?nico de 30 a 90% (180 a 540W) e pulso de vibra??o de 50 a 90%. No planejamento, a temperatura utilizada foi de 50 ?C, o tempo de rea??o de 30 min e o di?metro do bico ultrass?nico de 28 mm. Utilizou-se o software Statistica 8.0 para otimizar as vari?veis do processo, onde a raz?o molar foi otimizada em 1:14,87, concentra??o de catalisador em 1,17%, amplitude do bico ultrass?nico em 67,64% e pulso de vibra??o em 67,30%. Nas condi??es otimizadas pelo planejamento experimental (98,12% de convers?o de triglicer?deos), foi realizado um estudo cin?tico da rea??o nas temperaturas de 30, 40 e 50 ?C. A rea??o se apresentou com uma cin?tica de 2? ordem, em que a constante de velocidade da rea??o cresce com o aumento da temperatura. A energia de ativa??o foi quantificada em 79,129 kJ/mol. Por fim, foi realizado um estudo comparativo da produ??o de biodiesel por interesterifica??o na presen?a de ondas ultrass?nicas, com uma metodologia convencional (agita??o mec?nica), sendo verificado um aumento significativo de 13% da convers?o de triglicer?deos com a utiliza??o de ondas ultrass?nicas em compara??o com uma metodologia convencional / In this paper we present a study of the interesterification process of cottonseed oil (Gossypium hirsutum L.) with methyl acetate using potassium methylate as a catalyst in the presence of ultrasonic waves. In order to better understand the important process variables, we used an experimental design star type, a response surface methodology and statistical techniques. The experiments were carried out with molar ratio ranging from 1:8 to 1:24, percentage of catalyst from 0.1 to 1.3 % mass, amplitude of the ultrasonic nozzle 30 to 90 % (180 to 540 W) and pulse vibrating 50 to 90 %. In planning, the temperature used was 50 ?C, the reaction time 30 min and the ultrasonic nozzle diameter of 28 mm. Statistica 8.0 software was used to optimize the process variables, wherein the molar ratio was optimized in 1:14.87, catalyst concentration of 1.17 %, amplitude of the ultrasonic nozzle 67.64 % and vibration pulse of 67.30 %. For the optimized by experimental design (98.12 % of triglyceride conversion), we performed a kinetic study of the reaction at temperatures of 30, 40 and 50 ?C. The reaction was performed with 2nd-order kinetics in that the rate constant of the reaction increases with increasing temperature. The activation energy was quantified in 79.129 kJ/mol. Finally, we conducted a comparative study of the production of methyl esters by interesterification in the presence of ultrasonic waves, with a conventional method (mechanical stirring), with a significant increase of 13 % of triglyceride conversion with the use of ultrasonic waves compared with a conventional method.

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.