Banca de QUALIFICAÇÃO: JOSÉ DALADIÊ BARRETO DA COSTA FILHO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : JOSÉ DALADIÊ BARRETO DA COSTA FILHO
DATE: 14/12/2020
TIME: 14:30
LOCAL: https://meet.google.com/ujr-gfec-xvx
TITLE:

Corn cob valorization: Second generation ethanol production and use of residual lignin from enzymatic hydrolysis as a cationic dye adsorbent

KEY WORDS:

Agroindustrial Residue, Lignin, Adsorption, Dye

PAGES: 79
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

The conversion of lignocellulosic materials into fermentable sugars for ethanol production has been a promising alternative to increase the production of biofuels. However, the approach focused only on ethanol production is not adequate in terms of economic viability and sustainability. Given this context, the present work had as main objective to give an appreciation to the corn cob for the production of second generation ethanol as well as to apply the residual lignin as a cationic dye adsorbent. The effects of the organosolv (Os) and oxidative (Ox) pretreatments of corn cob were evaluated, as well as the combination of these (oxidation followed by organosolv - OxOs; and organosolv followed by oxidation - OsOx) and the synergistic effect in a single step in the presence of sulfuric acid (Oxs) and without acidification of the medium (GP). In compositional terms, the combined and combined action techniques OxOs, OsOx and Oxs were responsible for the highest rates of removal of lignin and hemicellulose. The glycerol-based liqueurs from the pre-treatments Os, Oxs and OxOs were chemically characterized. It was observed that the concentrations of reducing sugars were higher than glucose, being possible to infer that the cellulose remained mostly in the solid after the processes. Pre-treated as well as untreated biomasses were subjected to enzymatic hydrolysis with a 5% (m / v) solids load and 10.0 FPU / g biomass load for 48 hours. After saccharification, the hydrolyzate was separated to determine the concentration of reducing sugars and glucose. The highest concentrations were obtained with OxOs, while OsOx and Oxs showed statistically equal results, therefore, the hydrolysates of Oxs and OxOs were applied in fermentation tests for 72 hours with S. cerevisiae PE2 via separate hydrolysis and fermentation. Os hydrolyzate was used as a control in the experiments in order to evaluate oxidation. Rapid ethanol production in the initial 12 hours of incubation was achieved. The final concentrations of ethanol for Os, Oxs and OxOs were 10.13g / L, respectively; 11.41 g / L and 12.29 g / L. The solid residues of Os (ROs), Oxs (ROxs) and OxOs (ROxOs) after saccharification were washed with citrate buffer, dried in an oven at 80 ° C for 24 hours and finally characterized and applied in blue dye adsorption tests. methylene. The residues showed traces of polysaccharides not digested by the enzymes during saccharification, but with a major composition of lignin (approximately 70%). FTIRs indicate the digestibility of solids when compared to pre-treated materials, as well as the presence of hydroxyl, carbonyl and carboxylic groups. Methylene blue is rapidly captured in the initial minutes of the process, with a rapid reduction in concentration. The kinetics that best fitted the experimental data was the pseudo second order type. The equilibrium points were analyzed after 24 hours of incubation since despite the majority catch at the beginning, after 2 hours there was still a slow decay of the methylene blue concentration. The Langmuir isotherm had R²> 0.95, satisfactorily representing the experimental data. The estimated maximum adsorptive capacities of ROs, ROxs and ROxOs were, respectively, 199.52 mg / g 245.78 mg / g and 269.53 mg / g, being in agreement with the results obtained in batch (ROxOs> ROxs> ROs). The better performance of biomass residues that were subjected to oxidation can be justified due to the possible formation of carbonyl and carboxylic acid groups after cleavage of the aromatic lignin ring, positively influencing the adsorption of methylene blue. In view of what was discussed, the application of organosolv with temperature-activated persulfate oxidation in a single pretreatment step proved to be an efficient technique for cellulosic conversion in saccharification and consequently in ethanol production, as well as showing positive effects adsorption of cationic substances.

BANKING MEMBERS:
Externo à Instituição - CARLOS EDUARDO DE ARAÚJO PADILHA - UFRN
Presidente - 1584174 - DOMINGOS FABIANO DE SANTANA SOUZA
Interno - 1346198 - EVERALDO SILVINO DOS SANTOS
Externo à Instituição - PEDRO FERREIRA DE SOUZA FILHO