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Abstract  

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 process.

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Journal of Thermal Analysis and Calorimetry
Authors: S. Silva, M. Conceiçăo, A. Souza, S. Prasad, M. Silva, V. Fernandes, A. Araújo, and F. Sinfrônio

Abstract  

The powder and the bran of algaroba pods, submitted to drying temperatures of 55, 65, 75, 85, 95 and 105C, were studied by conventional and thermogravimetric methods. The dynamic thermogravimetric curves of the samples indicated the following thermal stability order: 105>55>65>95>85>75C. The powder and the bran of algaroba pods, dried at 55C, presented protein content higher and isothermal thermogravimetric profiles comparable. The calorimetric curves of samples, dried at 55C, indicated the gelatinization of starch.

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Journal of Thermal Analysis and Calorimetry
Authors: A. Souza, H. Danta, M. Silva, I. Santos, V. Fernandes, F. Sinfrônio, L. Teixeira, and Cs. Novák

Abstract  

The biodiesel obtained by transesterification by reaction between ester and an alcohol in the presence of catalyst. The purpose of this work is to evaluate the thermal and kinetic behavior of the methanol biodiesel derived from cotton oil. The quality analysis was done by gas chromatography and proton nuclear magnetic resonance spectrometry (1H NMR) in order to examine if the product meets with the requirements of the European Standard EN 1403. The thermogravimetric profile of the cotton biodiesel indicated that the decomposition steps are associated to the volatilization and/or decomposition of the methyl esters. Kinetic data was also obtained by thermal analysis.

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Abstract  

Thermogravimetry (TG) and mass spectrometry (MS) combined techniques have been used to investigate the thermal degradation and catalytic decomposition of high-density polyethylene (HDPE) over solid acid catalysts as H-ZSM-5, Al-MCM-41 and a hybrid material with a bimodal pore size distribution (H-ZSM-5/Al-MCM-41). The silicon/aluminum ratio of all catalysts is 15. Both thermal and catalytic processes showed total conversion in a single mass loss step. Furthermore, the catalytic conversion presents average reduction of 27.4%, in the onset decomposition temperature. The kinetic parameters were calculated using non-isothermal method. These parameters do not indicate significant differences between the thermal and catalytic processes. Even though, the presence of the catalysts changes the reaction mechanism, from phase boundary controlled reaction to random nucleation mechanism. Important difference in distribution of evolved products was detected when several catalysts were used. However, in all cases the main products were alkanes (C2, C3 and C4), alkenes (C3 and C4), dienes (C4 and C5) and traces of aromatic compounds.

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Journal of Thermal Analysis and Calorimetry
Authors: N. Santos, J. Santos, F. Sinfrônio, T. Bicudo, I. Santos, N. Antoniosi Filho, V. Fernandes, and A. Souza

Abstract  

The babassu (Orbignya Phalerata Mart.) 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 process.

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Journal of Thermal Analysis and Calorimetry
Authors: A. Vasconcelos, M. Dantas, M. Filho, R. Rosenhaim, E. Cavalcanti, N. Antoniosi Filho, F. Sinfrônio, I. Santos, and A. Souza

Abstract  

The influence of drying processes in the biodiesel oxidation was investigated by means of the oxidative induction time obtained from differential scanning calorimetry data. For this purpose, corn biodiesel was dried by different methods including: chemical (anhydrous sodium sulfate) and thermal (induction heating, heating under vacuum and with microwave irradiation). The drying efficiency was evaluated by monitoring IR absorption in the 3,500–3,200 cm−1 range and by the AOCS Bc 2-49 method. In general, the oxidative induction times increased inversely to the heating degree, except that of microwave irradiation, which was selective to water evaporation and caused low impact over the unsaturation of biodiesel. The DSC technique was shown to be a powerful tool to evaluate with high level of differentiation the influence of the drying process on the oxidative stability of biodiesel.

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Journal of Thermal Analysis and Calorimetry
Authors: L. Freire, T. Bicudo, R. Rosenhaim, F. Sinfrônio, J. Botelho, J. Carvalho Filho, I. Santos, V. Fernandes, N. Antoniosi Filho, and A. Souza

Abstract  

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-differential 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.

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Journal of Thermal Analysis and Calorimetry
Authors: F. S. M. Sinfrônio, J. C. O. Santos, L. G. Pereira, A. G. Souza, M. M. Conceiçăo, V. J. Fernandes Jr., and V. M. Fonseca
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Journal of Thermal Analysis and Calorimetry
Authors: J. C. O. Santos, I. M. G. Santos, F. S. M. Sinfrônio, M. A. Silva, E. V. Sobrinho, M. M. Conceiçăo, V. J. Fernandes Jr., and A. G. Souza
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Journal of Thermal Analysis and Calorimetry
Authors: Marta M. Conceição, V. J. Fernandes Jr., F. S. M. Sinfrônio, J. C. O. Santos, M. C. D. Silva, V. M. Fonseca, and A. G. Souza
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