Banca de QUALIFICAÇÃO: VITOR TROCCOLI RIBEIRO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : VITOR TROCCOLI RIBEIRO
DATE: 11/11/2022
TIME: 14:00
LOCAL: Via Google Meet
TITLE:

Influence of Tween 80 on pretreatment by steam and alkaline explosion, enzymatic hydrolysis and fermentation for ethanol production from green coconut fiber

KEY WORDS:

Steam Explosion, bioethanol, green coconut, Tween 80, SSSF.

PAGES: 155
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

Green coconut fiber has proved to be an interesting alternative for the production of bioethanol, as Brazil has one of the largest global productions of the fruit and its inadequate disposal causes environmental problems. However, the high recalcitrance of green coconut makes it difficult to convert it into large volumes of bioethanol. Pretreatments are necessary to destroy the crystalline structure of cellulose and increase the efficiency of enzymatic hydrolysis. Steam explosion pretreatment is a clean technology that has a low environmental impact, having as main consequence the removal of hemicellulose. Furthermore, the addition of non-ionic surfactants in the bioethanol production process has been studied as a strategy to increase its production and yield. The objective of this study was to evaluate the ethanol production from green coconut fiber using a combined steam explosion and alkaline pretreatment. Initially, the influence of the temperature and humidity in the steam explosion pretreatment were evaluated in the glucose production. Moreover, the use of Tween 80 (polysorbate 80) was evaluated in the pretreatment, enzymatic hydrolysis and fermentation processes. As there was no delignification after steam explosion and to increase enzymatic digestibility, an alkaline pretreatment with sodium hydroxide was carried out in sequence. The combination of steam explosion pretreatment and alkaline pretreatment of green coconut fiber led to cellulose contents higher than 47.22% (w/w) and maximum glucose yield equal to 54.74%. Surfactant did not increase delignification in the steam explosion pretreatment, however it increased the conversion to glucose when compared to experiments without Tween 80. The use of surfactant in enzymatic hydrolysis increased glucose production reaching a maximum value of 20.31 g/L with combined pretreated biomass when 1.0% (w/v) surfactant was added. In the absence of surfactant in any steps, the semi-simultaneous saccharification and fermentation (SSSF) strategy stood out over the simultaneous saccharification and fermentation (SSF). The SSSF increased the yield and ethanol production and the strain that obtained the best production was Saccharomyces cerevisiae PE2, reaching a maximum ethanol production equal to 24.88 g/L under 15% (w/v) solids. Different effects of Tween 80 were observed during fermentation. The use of 2.0% (w/v) Tween 80 reduced cell viability as well as reduced ethanol production in simulated medium, in SSF and SSSF. On the other hand, the use of 1.0% (w/v) Tween 80 increased the average ethanol production, although not enough to be statistically significant. To increase ethanol production under 30% (w/v) solids loading, SSSF variations were performed, including batch addition of biomass, batch addition of enzymes and temperature variation every 6 h. The SSSF with non-isothermal batch feeding and gradual addition of enzymes stood out, reaching a maximum ethanol produced of 48.21 g/L in the presence of 1.0% (w/v) Tween 80. Therefore, the results show that the use of the combined pretreatment generated a biomass with high cellulosic content that has a great potential for cellulosic ethanol production when fermentation strategies with Tween 80 were evaluated.

COMMITTEE MEMBERS:
Presidente - 1346198 - EVERALDO SILVINO DOS SANTOS
Interno - 3304882 - CARLOS EDUARDO DE ARAÚJO PADILHA
Externo ao Programa - 027.194.253-38 - SÉRGIO DANTAS DE OLIVEIRA JÚNIOR
Externo à Instituição - PEDRO FERREIRA DE SOUZA FILHO - UFPE