Pré-tratamento hidrotérmico do bagaço de malte (BSG) visando a produção de etanol de segunda geração
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2019-02-26
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Universidade Federal de Goiás
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Brazil is the third largest producer of beer in the world and brewer’s spent grain (BSG) is the
main residue of this industry. As a low-cost, available lignocellulosic material, it has become
an attractive alternative for the production of biofuels and other chemicals. Thus, to be able to
take advantage of BSG as a raw material it must first be pre-treated. Hydrothermal pre-
treatment allows the removal of the fraction of hemicellulose present in the lignocellulosic
material and brake the lignocellular crystallinity. In this work, initially was performed the
characterization of the BSG in natura, obtaining 25.1% of cellulose, 20.9% of hemicellulose,
20.3% of lignin and 28.0% of proteins. Evaluating the effect of temperature and time of
hydrothermal pretreatment, the best result was at 160°C and 60 min, with cellulose yield of
64.8% and removal of hemicellulose of 62.0%. In a second experiment, the temperature and
solids content of the pretreatment and its effect on the enzymatic hydrolysis were analyzed,
obtained better glucose yield, 74.1%, in the enzymatic hydrolysis of the pretreated at 180°C
and 40 g of dry BSG, containing 0.020 g furfural, 0.062 g HMF and 0.902 g acetic acid (per
100 g dry BSG) which are inhibitors of the fermentation process. As the present study aimed
at the production of 2G ethanol by fermentation, the condition of pretreatment 160 °C, 80 g
was chosen for the pretreatment kinetic study, since it presented a high glucose yield, 66.3%,
and a lower concentration of inhibitors of the fermentation process with 0.020 g Furfural
0.020 g HMF and 0.444 g acetic acid (per 100 g dry BSG). In a second condition,
pretreatment kinetics were performed for comparison reasons (200°C / 80g). Samples were
withdrawn at times 0, 5, 10, 20, 40 and 60 min. Results showed that the reaction time of 10
min obtained better cellulose yield in the solid fraction at 160°C and at 200°C the highest
yield of cellulose was in 5 min. In the liquid fraction, the concentrations of oligomers did not
change significantly when varied the reaction time at 160°C, while in the temperature of
200°C there was a considerable increase of oligomers in 5 minutes. The amounts of glucose
released in the processes studied were not satisfactory high to consider hydrothermal
pretreatment to BSG as feasible for the production of second generation ethanol.
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MAIONE, N. R. Pré-tratamento hidrotérmico do bagaço de malte (BSG) visando a produção de etanol de segunda geração. 2019. 54 f. Dissertação (Mestrado em Engenharia Química) - Universidade Federal de Goiás, Goiânia, 2019.