Optimization of acid and alkali pretreatment of deteriorated abaca fiber for bioethanol production

Date

12-2010

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Veronica P. Migo

Abstract

PAITA, CONSORTIA ADELWISA M. University of the Philippines at Los Banos, December 2010. Optimization of Acid and Alkali Pretreatments of Deteriorated Abaca Fiber for Bioethanol Production.

Adviser: Dr. Veronica P. Migo Advisory Committee Members: Dr. Ernesto J. Del Rosario Prof. Joy Elaine P. Kaligayahan

Several lignocellulosic biomasses are being studied as substrates to produce bioethanol as an alternative and renewable source of energy. This study utilized deteriorated abaca fiber (DAF), a natural fiber from Moor tern& nee, as a lignocellulosic substrate. Compositional analysis of the untreated substrate was first done according to NREL standard procedures. The compositional analysis (moisture-free basis) were as follows: total carbohydrate (73.48%), cellulose content (30.35%), alcohol extractives (6.14%), total ash (4.90%), acid soluble (4.52%) and acid insoluble (10.41%) lignin. Optimization of dilute acid and dilute alkali pretreatments was determined in terms of three variables: acid and base concentration (1.84-9.20% w/v and 1-5% w/v respectively), pretreatment time (15-60 minutes) and temperature (80-120°C). The response measured in the experiments was the cellulose content of DAF after pretreatment. StatEase Design-Expert v.7 software was utilized to statistically analyze the data. Response Surface Methodology was employed using Box Behnken design for a quadratic model to determine the optimum pretreatment conditions that will give maximum response (in terms of cellulose content) after pretreatment. For dilute acid pretreatment, the optimum condition was found to be 1.84% w/v H2SO4, 60 minutes and 80°C. Compositional analysis was done on acid pretreated DAF where cellulose content was 49.98% (-19% increase), acid soluble and insoluble lignin content were 1.36% and 12.16% respectively. The optimum alkali pretreatment was at 1% w/v NaOH, 15 minutes and 80°C. Cellulose content of base pretreated OAF was 46.76% (-16% increase) , acid soluble and insoluble lignin content were 0.65% (-4% decrease) and 8.51% (-2% decrease) respectively. Based on the results, dilute alkali pretreatment can delignify more than acid while acid can effectively solubilize hemicelluloses as compared to base. Both acid and alkali pretreatments can significantly increase cellulose accessibility in DAF. Acid and alkali pretreated DAF at optimum conditions were also subjected to SEM. It has been observed that untreated OAF was still intact and recalcitrant while only same of the structure of acid pretreated OAF was degraded. As for base pretreated DAF, the lignin-carbohydrate complex was disrupted to a great extent. Enzymatic saccharification was done using Accelerase® 1500 from Genencor® International. The highest saccharification efficiency (42.44%) was on base pretreated OAF indicating a higher enzyme digestibility of base pretreated OAF. Separate Hydrolysis and Fermentation (St-IF) was done using Pichia myanmarensis. Sequential Non-isothermal Simultaneous Saccharification and

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2010 C4 P35

Document Type

Thesis

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