Banca de DEFESA: MARCIA ANDREA GOMES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARCIA ANDREA GOMES
DATE: 20/04/2023
TIME: 15:00
LOCAL: Sala de videoconferencia RNP_UFBA_PEI
TITLE:

STUDY OF THE PRODUCTION OF LIGNOCELLULOSIC ETHANOL FROM
RESIDUES FROM COCONUT CULTIVATION.

KEY WORDS:

green coconut shell, coconut-tree leaflet, enzymatic hydrolysis, fermentation,
detoxification, biomass, clean energy.

PAGES: 94
BIG AREA: Engenharias
AREA: Engenharia de Produção
SUMMARY:

The use of lignocellulosic biomass for the production of second-generation ethanol, such as the green coconut husk, implies the development and improvement of the stages of conversion of sugars into ethanol using a fermentative pathway. Thus, the execution of the pre-treatment step becomes necessary, responsible for breaking the lignocellulosic matrix, leaving it accessible to enzymatic attack in the subsequent step, the hydrolysis. With the available sugar monomers, the yeast converts them to ethanol in the fermentation step. Thus, this work aims to study the saccharification and fermentation configurations, using coconut cultivation residues as carbon sources, with the objective of evaluating the best saccharification and fermentation conditions for E2G production. Initially, the hydrothermal pretreatment (HPT) was carried out in a PARR type reactor using 15% (m/v) of solids, at 195°C, 10 min and 200 rpm. In parallel, an experimental design was carried out for the acid pretreatment (APT) (factors: H2SO4 concentration and temperature) aiming at the optimization of the pretreatment operational conditions. The function of glucose, conditions of 1% (v/v) H2SO4 at 100 °C for green coconut shell (GCS), 2% (v/v) H2SO4 at 120 °C for coconut-tree leaflet (CLL) and 2% (v/v) H2SO4 at 100 °C for the coconut-tree leaf stalk (CLS) followed for enzymatic hydrolysis, using 7.5 % (m/v) of solids and 20 FPU/g dry biomass of Cellic Ctec2 supplemented with 10% Cellic Htec. After 72h of reaction, glucose concentrations reached 31.85 and 19.07 g/L for the hydrolysis of GCS submitted to PTH and PTA. Regarding the behavior of CLL in hydrolysis, 21.31 and 13.65 g/L of glucose concentration were reached when this biomass was submitted to HPT and APT. For CLS, 45.39 and 21.01 g/L of glucose were obtained after HPT and APT, respectively. These results showed that enzymatic hydrolysis using hydrothermal pretreatment was more efficient than the results obtained for pretreated acidic biomasses. Then, the samples went on to fermentation with the yeast Kluyverkomyces marxianus at 37°C/24 h. In this step, it is possible to verify that practically all the glucose and xylose contents were consumed by the yeast. However, the ethanol yield reached values between 47 and 80%, indicating possible problems of a toxic nature, the production of secondary compounds, acetic acid, furfural and 5-hydroxymethylfurfural (HMF). A preliminary study was carried out to increase the fermentation efficiency in sugarcane bagasse hydrolyzate, known biomass, and submitted to hydrothermal (195 ºC, using 200 rpm for 10 min) and acid (0.5% (v/v) pretreatments.) of sulfuric acid at 121ºC for 15 min) and (10% w/v solids load). The enzymatic hydrolysis of the pre-treated material was performed using the CellicCtec® enzyme complex (60 FPU/dry biomass, 50 mM citrate buffer and pH 4.8) at 50ºC using 150 rpm for 72h. Before the detoxification process, a test was carried out with the species of Saccharomyces cerevisiae to verify if the compounds furfural (1 and 4g.L-1) and acetic acid (1 and 5% v/v) exerted significant inhibition in the tested species. The detoxification process evaluated the concentration of activated carbon (1, 3 and 5% w/v) and the process time (30, 45 and 60 min) at 30 ºC, 150 rpm for 24 h. The presence of furfural and acetic acid had a strong influence on the species considered, affecting more than 90% of the consumption of sugars in the medium. The detoxification process increased the fermentation efficiency by 13% for the hydrolysateobtained hydrothermally, while for the acid there was no significant difference. Thus, it was possible to conclude that the study of process conditions increased ethanol production compared to values already reported in previous studies with green coconut husk. And it identified the potential of the coconut leaf for the production of second-generation ethanol. It also verified that the detoxification conditions can be adapted to the biomass of coconut cultivation to increase efficiency and make the results feasible for industrial production.

COMMITTEE MEMBERS:
Externo à Instituição - Antônio José Gonçalves da Cruz
Externa à Instituição - Andrea Lopes de Oliveira Ferreira
Externa à Instituição - Martha S. R. dos Santos Rocha
Externo à Instituição - CARLOS EDUARDO DE FARIAS SILVA - UFAL
Presidente - 1677204 - ELAINE CHRISTINE DE MAGALHAES CABRAL ALBUQUERQUE
Externa à Instituição - Renata Maria Rosas Garcia Almeida