Green Liquor Pretreatment for Hardwood chips to Ethanol conversion strategies

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dc.contributor.advisor Robert Kelly, Committee Member en_US
dc.contributor.advisor Hasan Jameel, Committee Co-Chair en_US
dc.contributor.advisor Lucian Lucia , Committee Chair en_US Diaz, Joscelin Teresita en_US 2010-04-02T18:02:40Z 2010-04-02T18:02:40Z 2009-12-02 en_US
dc.identifier.other etd-11052009-114315 en_US
dc.description.abstract Modified Green Liquor pretreatment is a novel high sulfide pretreatment method that enhances carbohydrate stability. The influence of hardwood chips pretreatment with green liquor was investigated under alkaline conditions of 12% and 16% TTA, and sulfidities of 0%, 12.5%, 25%, and 37.5% to see its effect on the sugar recovery. Also, ethanol was added in the pretreatment conditions of 12%TTA and 25%S as an Organosolv pretreatment method. Quantitative analyses of glucose, xylose, mannose, and carbohydrates yield is discussed. The influence of pretreatment conditions such as alkalinity and sulfidity charge were the main variables controlled to analyze their influence in the carbohydrate yield. The results suggest that higher sulfidity promotes an increase in delignification, and also that this delignification is more notable in the samples pretreated with ethanol. The pretreated pulps were then hydrolyzed with cellulase, xylanase, and β-glucosidase enzymes. After enzymatic hydrolysis with these commercial cellulases enzymes, higher glucose yields were obtained at higher sulfidity and higher ethanol concentration in the liquor. The results also indicated that higher enzyme activity exhibited higher carbohydrates and glucan yield. The carbohydrates yield was 70.6% for hardwood chips pretreated with 16%TTA, 37.5%S, and hydrolyzed with cellulases at 20 FPU/g pulp. However, the higher carbohydrates yield obtained was 75.7% for the pulps pretreated at 20% ethanol and 20 FPU/g pulp. Different techniques were applied in the samples 16%TTA, 0%S and 37.5%S, and 12%TTA, 25%S, 20%ethanol to determine its pretreatment effect on lignin. ToF-SIMS technique was used to detect the changes in cellulose/lignin composition and then compare the results with ones the obtained from the sugar analysis using Ion Exchange Chromatography. ToF-SIMS suggested that the removal of lignin is mainly localized on the sample surface. The molecular weight distribution of lignin using Size Exclusion Chromatography technique was also studied. The results shown a decrease in the molecular weight when sulfidity was increased. It is hypothesized that this happened mainly due to cleavage of lignin in the β-O-4 linkage that decrease the chain length of the residual lignin. Green liquor has the advantage of altering the lignin structure, and preserving the celluloses and hemicelluloses present in the biomass. An economic analysis based in different assumptions was elaborated to compare all the study cases. In general the results shown that samples pretreated with higher sulfidity always shown better profit per liter compared with lower sulfidity. Also, in the case of the samples pretreated with ethanol, the profit was even better than without ethanol. But, variations in ethanol lost during the process shown that this method is not as attractive as the pretreatment at high sulfidity and high total titratable alkali. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject pretreatment en_US
dc.subject enzymes en_US
dc.subject wood en_US
dc.title Green Liquor Pretreatment for Hardwood chips to Ethanol conversion strategies en_US MS en_US thesis en_US Wood and Paper Science en_US

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