Authors:M. Rodrigues F, A. Souza, I. Santos, T. Bicudo, M. Silva, F. Sinfrônio, and A. Vasconselos
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.
Authors:S. Silva, M. Conceiçăo, A. Souza, S. Prasad, M. Silva, V. Fernandes, A. Araújo, and F. Sinfrônio
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.
Authors:A. Souza, H. Danta, M. Silva, I. Santos, V. Fernandes, F. Sinfrônio, L. Teixeira, and Cs. Novák
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.
Authors:F. Sinfrônio, A. Souza, Ieda Santos, V. Fernandes Jr., Cs. Novák, and Zsuzsanna Éhen
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
Authors:N. Santos, J. Santos, F. Sinfrônio, T. Bicudo, I. Santos, N. Antoniosi Filho, V. Fernandes, and A. Souza
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.
Authors:A. Vasconcelos, M. Dantas, M. Filho, R. Rosenhaim, E. Cavalcanti, N. Antoniosi Filho, F. Sinfrônio, I. Santos, and A. Souza
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.
Authors:L. Freire, T. Bicudo, R. Rosenhaim, F. Sinfrônio, J. Botelho, J. Carvalho Filho, I. Santos, V. Fernandes, N. Antoniosi Filho, and A. Souza
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.