Banca de DEFESA: HELLOCKSTON GOMES DE BRITO
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : HELLOCKSTON GOMES DE BRITO
DATE: 04/07/2023
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: 98
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:
Large volumes of green coconut husk residues are generated from the exploration of the fruit. Thus, arousing interest in the use of this lignocellulosic material as a raw material for the production of biofuels. Therefore, the present study evaluates the influence of different pre-treatments, aiming at using coconut fiber to obtain cellulosic ethanol, being: sulfuric acid (H2SO4, 1% (v/v)) and steam explosion, as well as their combination (combined pre-treatments) with sodium hydroxide (NaOH, 1 and 4% (m/v)) and alkaline hydrogen peroxide (H2O2, 3 and 6% (m/v)). Were also evaluated separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and semi-simultaneous saccharification, and fermentation (SSSF) strategies using the enzyme cocktail Cellic CTec2 and the yeast Saccharomyces cerevisiae (PE-2). The evaluation of the pre-treatments 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 the sugars during the hydrolysis and fermentation processes. The results of the composition of materials and conversion of sugars applied in the tests indicated that the acid sulfuric 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 hydroxide provided higher levels of delignification, facilitating the enzymatic attack during the hydrolysis step. It is noteworthy that practically all the hemicellulose was hydrolyzed in the acid pre-treatment, thus, a significant concentration of xylose (10.5 g/L) was recorded in its liquid fraction, which was higher than that of the steam explosion (2.53 g/L). The use of sulfuric acid pre-treatments and steam explosion were effective to remove the hemicellulose present in the coconut fiber, but the enzymatic digestibility values of the combined pre-treated materials were low (cellulosic conversion less than 50%). 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, with the best results obtained for the load of 10.0 FPU/g for using the ACN4 pre-treatment and 15.0 FPU/g for the EXPN4 pretreatment, with cellulosic conversions 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 SSSF strategy, when using the acid-alkaline pre-treatment with NaOH (4.0% m/v), showed a better result compared to SSF, with a cellulosic ethanol yield of 46.67% and 18.37±0.91 g/L of ethanol. HFS, on the other hand, did not show results. For all these reasons, green coconut fiber proved to be suitable to be used to obtain second-generation ethanol (2G).
COMMITTEE MEMBERS:
Presidente - 1346198 - EVERALDO SILVINO DOS SANTOS
Interno - 3304882 - CARLOS EDUARDO DE ARAÚJO PADILHA
Interna - 3214434 - NATHALIA SARAIVA RIOS
Externo à Instituição - SÉRGIO DANTAS DE OLIVEIRA JÚNIOR - INPA