Navegando por Autor "Sinfrônio, F. S. M."
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Artigo Antioxidative properties of hydrogenated cardanol for cotton biodiesel by PDSC and UV/VIS(Springer, 2009-04-27) Bicudo, Tatiana de Campos; Rodrigues Filho, M. G.; Souza, A. G.; Santos, I. M. G.; Silva, M. C. D.; Sinfrônio, F. S. M.; Vasconcelos, A. F. F.Biodiesel is a non-toxic biodegradable fuel that consists of alkyl esters produced from renewable sources, vegetal oils and animal fats, and low molecular mass alcohols, and it is a potential substitute for petroleum-derived diesel. Depending on the raw materials used, the amount of unsaturated fatty acids can vary in the biodiesel composition. Those substances are widely susceptible to oxidation processes, yielding polymeric compounds, which are harmful to the engines. Based on such difficulty, this work aims to evaluate the antioxidant activity of cashew nut shell liquid (cardanol), as additive for cotton biodiesel. The oxidative stability was investigated by the pressure differential scanning calorimetry (PDSC) and UV/Vis spectrophotometer techniques. The evaluated samples were: as-synthesized biodiesel – Bio T0, additivated and heated biodiesel – Bio A (800 ppm L –1 of hydrogenated cardanol, 150°C for 1 h), and a heated biodiesel – Bio B (150°C, 1 h). The oxidative induction time (OIT) analyses were carried out employing the constant volume operation mode (203 psi oxygen) at isothermal temperatures of 80, 85, 90, 100°C. The high pressure OIT (HPOIT) were: 7.6, 15.7, 22.7, 64.6, 124.0 min for Bio T0; 41.5, 77.0, 98.6, 106.6, 171.9 min for Bio A and 1.7, 8.2, 14.8, 28.3, 56.3 min for Bio B. The activation energy (E) values for oxidative processes were 150.0 1.6 (Bio T0), 583.8 1.5 (Bio A) and 140.6 0.1 kJ mol –1 (Bio B). For all samples, the intensities of the band around 230 nm were proportional to the inverse of E, indicating small formation of hyper conjugated compounds. As observed, cardanol has improved approximately four times the cotton biodiesel oxidative stability, even after the heating processArtigo Influence of the storage on the thermo-oxidative stability of methyl and ethyl esters by PDSC(Springer, 2011-02-14) Bicudo, Tatiana de Campos; Candeia, R. A.; Sinfrônio, F. S. M.; Queiroz, N.; Barros Filho, A. K. D.; Soledade, Luiz Edmundo Bastos; Santos, I. M. G.; Souza, A. L.; Souza, A. G.Biodiesel oxidation is a complex process widely influenced by the chemical composition of the biofuel and storage conditions. Several oxidation products can be formed from these processes, depending on type and amount of the unsaturated fatty acid esters. In this work, fatty acid methyl and ethyl esters were obtained by basecatalyzed transesterification of soybean oil and physicochemically characterized according to standards from ASTM, EN, and ABNT. The thermal and oxidative stabilities of biodiesel samples were investigated during the storage process by pressure differential scanning calorimetry (PDSC) and by viscosity measurements. Absolute viscosities of biodiesels after accelerated aging were also determined. The viscosity increased as the aging temperature and time were raised. The results showed that oxidation induction can occur during storage, decreasing the biodiesel stability. PDSC analysis showed that during storage under climate simulation the values of high-pressure oxidative induction times (HPOIT) were reduced for both FAEE and FAMEArtigo Themo-oxidative stability ald cold flow properties of babassu biodiesel by PDSC ans TMDSC techniques(Springer, 2009-04-27) Bicudo, Tatiana de Campos; Santos, N. A.; Santos, J. R. J.; Sinfrônio, F. S. M.; Santos, I. M. G.; Antoniosi Filho, N. R.; Fernandes Jr, V. J.; Souza, A. G.The babassu (Orbignya PhalerataMart.) biodiesel has lauric esters as main constituents, resulting in high oxidative stability and low cloud and freezing points. In order to reduce these side effects, the saturated ethyl esters content was reduced by means of winterization process. The TMDSC and PDSC techniques were used to verify the thermal and oxidative stabilities of the ethyl babassu biodiesel. During the heating stage, the winterized solid phase of ethyl esters presented an endothermic transition associated to the solidification process. This behavior was not observed for the liquid winterized FAEE, confirming the efficiency of the winterization processArtigo Thermal investigation of oil and biodiesel fromJatropha curcasL.(Springer, 2009-06-19) Bicudo, Tatiana de Campos; Freire, L. M. S.; Rosenhaim, R.; Sinfrônio, F. S. M.; Botelho, J. R.; Carvalho Filho, J. R.; Santos, Ieda Maria Garcia dos; Fernandes Júnior., V. J.; Antoniosi Filho, N. R.; Souza, A. G.Biodiesel is susceptible to autoxidation if exposed to air, light and temperature, during its storage. Physic nut (Jatropha curcas L.) seeds show potential application for biodiesel production since its oil yields high quality biodiesel. This work aims to evaluate the thermal behavior of the physic nut oil and biodiesel, from several Brazilian crops, by means of thermoanalytical techniques. Thermogravimetry (TG) and pressurized-ifferential scanning calorimetry (PDSC) were used in order to determine the applicability of physic nut biodiesel as fuel. Results suggest that physic nut biodiesel is a practical alternative as renewable and biodegradable fuel able to be used in diesel motors