Banca de QUALIFICAÇÃO: HELLOCKSTON GOMES DE BRITO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : HELLOCKSTON GOMES DE BRITO
DATE: 18/04/2023
TIME: 14:00
LOCAL: Via Google Meet
TITLE:

Application of different pretreatment strategies to convert green coconut fiber into cellulosic ethanol

KEY WORDS:

lignocellulosic material, green coconut, pretreatments, enzymatic hydrolysis, alcoholic fermentation, 2G ethanol

PAGES: 93
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

The present study evaluates the influence of different pretreatments, aiming at the use of coconut fiber to obtain cellulosic ethanol, including sulfuric acid (H₂SO₄) and steam explosion, as well as their combination (combined pretreatments) with sodium hydroxide (NaOH) and alkaline hydrogen peroxide (H₂O₂). It also evaluates different hydrolysis and fermentation strategies, simultaneous saccharification and fermentation (SFS), and semi-simultaneous saccharification and fermentation (SFSS) using Saccharomyces cerevisiae (PE-2). The evaluation of the pretreatments was carried out based on the analysis of the chemical composition of the materials, using High-Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (DRX) for the crystallinity index. HPLC was also used to evaluate sugars during the hydrolysis and fermentation processes. The results of the composition of materials and conversion of sugars indicated that the acid pretreatment followed by NaOH (4.0% m/v) (ACN4) and the pretreatment with a steam explosion followed by NaOH (4.0% m /v) (EXPN4) were the best, since the 4% concentration of the hydroxide provided higher levels of delignification, facilitating enzymatic attack during the hydrolysis step. It is noteworthy that the hemicellulose was fully hydrolyzed in the acid pretreatment, with a significant generation of xylooligosaccharides (1.46 g/L) being observed in the liquid fraction of the steam explosion. The use of acid pre-treatments and steam explosion were effective to remove the hemicellulose present in the coconut fiber, but the enzymatic digestibility values of the pre-treated materials were low (cellulosic conversion less than 50.0%). In this case, a glucose production of 15.59 ±0.63 g/L was obtained for ACN4 and 13.28 ±0.75 g/L for EXPN4. In the enzymatic hydrolysis, the enzymatic cocktail Cellic CTec2 was used in different enzymatic loads and the best results were obtained for a load of 10.0% FPU/g using the ACN4 pretreatment and 15.0% FPU/g for the EXPN4 pretreatment, with cellulosic conversions of 48.68 ± 1.98% and 50.24 ± 2.87%, glucose content 15.59 ± 0.63 g/L and 13.28 ± 0.75 g/ L, for the ACN4 and EXPN4 assays, respectively. Regarding the fermentation strategies that were carried out varying the solid load, between 5% and 15% (m/v), the SFSS strategy, when using the acid-alkaline pre-treatment with NaOH (4.0% m/v), showed better results compared to SFS, with a cellulosic ethanol yield of 46.67% and providing 18.37±0.91 g/L of ethanol, thus showing that green coconut fiber has the potential to second-generation (2G) ethanol production.

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