Caracterização, estabilidade oxidativa e determinação do potencial energético do biodiesel derivado do mamão (carica papaya L.): uma fonte não convencional.

• Ano de defesa: 2010
• Autor(a) principal: Melo, Maria Ladjane Sodré de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraí­ba; BR; Química; Programa de Pós-Graduação em Química; UFPB
• Palavras-chave em Português: Sementes de mamão; Óleo; Biodiesel; Papaya seeds; Oil; CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/tede/7173

The aim of this research was to study the chemical and physical properties of the papaya seeds of three different cultivars produced in Brazil: Sunrise Solo (Hawaii), Golden and Formosa. The chemical composition of the seeds and the extracted oils, physical chemical properties of oils and obtained biodiesel were analyzed to evaluate the industrial use of this disposable residue as renewable energy source. Golden and Solo Sunrise cultivars presented lower fruit weight (391.92 and 590.32 g) compared to Formosa cultivar (1318.16 g) but a higher seed yield of 2.54 and 1.43% respectively against 0.61% of Formosa. The chemical composition of the seeds shown high protein content (23.58 to 25.46 g/100 g), fibers (16.07 to 19.19 g/100 g) and minerals (5.12 to 6.48 g/100 g) among the three cultivars with emphasis on Fe and P (104.18 mg/g and 634.12 mg/g) for the cultivars Golden Sunrise Solo cultivars. The oil content was ± 28%. The major component were oleic acid (69.78%, 70.13% and 72.04%) and palmitic acid (18.95%, 18.89% and 18.20%) respectively for Golden, Sunrise Solo and Formosa cultivars. The acidity index (1.0, 0.98 and 1.03), iodine index (71.30, 70.26 and 70.45) and saponification index (190.2, 190.14 and 189.98) were found form the three papaya variety. Methyl transesterification of the Golden oil was carried out by 0.5% basic catalysis, 1:8 molar ratio, 45°C temperature and the product was identified by TLC, GC-MS, IR and 1H and 13C NMR techniques. The yield of the methyl esters (92.07%), was gravimetrically determined according to the stoichiometry of the reaction. The kinetics of acid catalyzed methyl transesterification using the same oil was evaluated by TLC and the yield of esterification was determined by reducing the acidity index of the reaction medium. The reaction medium used and results found were: 1:9 molar ratio and 80°C temperature the acidity index was reduced from 28 to 3.31 and 3.12 mg KOH/g sample, yielding of 88.18% and 88.86% respectively, at 1.0 and 1.4% catalyst after 8 hours of reaction. In a second stage of the reaction after 2 hours, the acidity index were 1.8 mg KOH / g (1.0% of catalyst) and 1.6 g KOH / g (1.4% of catalyst) with esterification maximum respectively 93.57 and 94.28%. The biodiesel obtained by basic catalysis showed 0.35 mg KOH / g acidity value, 0.88 g/cm3 density, 6.0 mm2 / s kinematic viscosity, 1°C cloud point, -1°C flow point and 62.83 cetane number. The power generation consumption, in L / h, were 0.5837 (B100), 0.5806 (B50), 0.5814 (B20), 0.6122 (B10), 0.6225 (B5) compared to 0.6981 (diesel), indicating its high calorific power. Thermal stability studies showed that the initial temperature of mass loss in TGA (155 ° C) match with the temperature variation of enthalpy by DSC curve and the initial oxidative event shown in non-isothermal curve PDSC indicating superior thermo-oxidative stability comparing to Soybean biodiesel where similar thermal events begin at a temperature of 100 º C. The oxidative stability (25 hours) was evaluated by Rancimat test. This result was confirmed by PDSC, where the variation of the baseline occurred at 54 minutes after reaching the temperature of the isotherm, at 110°C, and any other thermal event was observed during the entire period of the experiment (10 hours), indicating no oxidation reactions. The peroxide index was evaluated 58.4 meq / kg by using an oven (65 ºC) for a period of 25 days, showing a high stability if compared with the sunflower oil biodiesel, which according to the literature and in the same procedures presented a peroxide index of 300 meq / kg in seven days. The rheological study showed a Newtonian behavior and an absolute dynamic viscosity of 5.3 ± 9.1.10-5 m.Pa.s.