Date of Award

January 2015

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Buchang Shi

Department Affiliation

Chemistry

Second Advisor

Darrin L. Smith

Department Affiliation

Chemistry

Third Advisor

Tanea T. Reed

Department Affiliation

Chemistry

Abstract

Lignocellulosic biomass is an abundant, renewable and environmentally friendly raw materials that can be converted into biofuels as an efficient alternative energy source. Sugar production is one of the key steps in converting biomass to fuels and chemicals. In order to enhance the accessibility of lignocellulosic biomass to catalytic enzyme, microorganism, and other types of catalysis during bioprocessing, the pre-treatment of lignocellulosic biomass is needed. To depolymerize the lignocellulosic materials, a 7% NaOH/12% urea solution was used. Selection of enzyme from Novozyme was performed, as a result, NS22074, a Cellulase complex was used throughout the research. Under the same reaction conditions, the treated cotton fibers were converted to glucose in almost 65% yield (based on 90% cellulose in cotton) within 2 hours at room temperature (22ºC); while the conversion for non-treated cotton fibers were only 20%. Different composition of NaOH/urea as the de-polymerization solutions were used and studied. Cellulose dissolution with NaOH/thiourea , LiOH/urea, KOH/urea were also used and studied. Next step is to apply the same pretreatment method to three different switchgrass samples, Alamo, Kanlow, and Bluegrass. Reaction time for swithgrass samples takes longer than that for cotton fibers, pretreated switchgrass samples were converted to glucose in 45% yield (based on 25% cellulose in switchgrass) within 3 days; non-treated swithgrass samples were only 20% yield. Besides cotton fibers, Avicel® PH-101 commercial cellulose, printer paper, luffa, and a cotton t-shirt were also treated with this novel procedure. Acid hydrolysis using 10% HCl and 5% HCl was performed. The results showed that there is almost no glucose conversion present. Scanning electron microscopy (SEM) studies of the treated and non-treated samples have showed that the structure of treated sample is significantly different from the non-treated ones. High-performance liquid chromatography (HPLC) result showed that glucose is the only product produced. Fourier transform infrared spectrometry (FTIR) results showed a sharp peak in both 3400cm-1 and 1500 cm-1 region for pretreated samples, which explains less hydrogen bonding can allow urea hydrates self-assembled at the surface of the NaOH for enzymatic hydrolysis.

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