Authors:M. Dantas, A. Almeida, Marta Conceição, V. Fernandes Jr, Iêda Santos, F. Silva, L. Soledade, and A. Souza
This work presents the characterization and the kinetic compensation
effect of corn biodiesel obtained by the methanol and ethanol routes. The
biodiesel was characterized by physico-chemical analyses, gas chromatography,
nuclear magnetic resonance and thermal analysis. The physico-chemical properties
indicated that the biodiesel samples meet the specifications of the Brazilian
National Agency of Petroleum, Natural Gas and Biofuels (ANP) standards. The
analyses by IR and 1H NMR spectroscopy indicated
the ester formation. Gas chromatography indicated that biodiesel was obtained
with an ester content above 97%. The kinetic parameters were determined with
three different heating rates, and it was observed that both the methanol
and ethanol biodiesel obeyed the kinetic compensation effect.
Authors:M. Dantas, Marta Conceição, V. Fernandes Jr, Nataly Santos, R. Rosenhaim, Aldalea Marques, Iêda Santos, and A. Souza
This work evaluates the thermal and kinetic
behaviour of corn biodiesel obtained by the methanol and ethanol routes. As
to the TG curves, in air three thermal decomposition steps are for the methanol
biodiesel and two steps are for the ethanol biodiesel. These steps are related
to the evaporization and/or combustion of the methyl and ethyl esters, respectively.
The corn oil presented four thermal decomposition steps in air, and only one
step in nitrogen. These steps were attributed to the evaporization and/or
decomposition of triglycerides. The TG and DTA profiles of the biodiesel approach
the mineral diesel oil ones.
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.