Author : Indira Priya Samayam
Publisher :
ISBN 13 :
Total Pages : 208 pages
Book Rating : 4.:/5 (781 download)
Book Synopsis Characterization and Saccharification of Ionic Liquid Pretreated Lignocellulosic Biomass by : Indira Priya Samayam
Download or read book Characterization and Saccharification of Ionic Liquid Pretreated Lignocellulosic Biomass written by Indira Priya Samayam and published by . This book was released on 2011 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this dissertation research is to gain a more fundamental understanding of the impact of ionic liquid (IL) pretreatment of lignocellulosic biomass in production of ethanol and other chemicals through a sugar platform and biochemical conversion of polysaccharides to monomeric sugars. Recalcitrance of cellulose hydrolysis is a primary roadblock for efficient enzymatic conversion of lignocellulosic biomass to monomeric sugars that are fermented to ethanol or other products. The structure of lignocellulosic biomass is rendered amenable to enzymatic saccharification upon IL pretreatment. Changes in the structure of cellulose in relation to the biomass digestibility with varying ionic liquid (IL) pretreatment were examined. Conversion of native cellulose I to amorphous cellulose or cellulose II improved the susceptibility of cellulose to enzymatic hydrolysis. The performance of commercial enzyme mixtures were evaluated through saccharification of IL pretreated biomass substrates (poplar and switchgrass) at low biomass slurry concentrations. Poplar and switchgrass hydrolysis with commercial cellulase, Spezyme CP, and Multifect Xylanase showed synergism between the two enzymes. However, switchgrass hydrolysis was less complete than that of poplar, likely due to differences in hemicellulose structural features. Hydrolysis of polysaccharides in lignocellulose at high biomass slurry concentrations is essential in economical fermentation of hydrolyzates to ethanol and other products. Commercial enzyme mixtures were varied for simultaneous or sequential hydrolysis and fermentation of pentose and hexose sugars with Pichia stipitis for IL treated poplar. In sequential hydrolysis of poplar at modest enzyme loadings of 9 mg/g xylan Multifect Xylanase, 1.8 mg/ g xylan SXA (ß-xylosidase) at 50°C in the first step and 10 FPU/g glucan Spezyme CP, and 40 CBU/g glucan Novozyme 188 at 25°C in the second step, the yields of glucose and xylose at 15% (w/v) solid loadings were 61% and 83%, respectively. The incomplete hydrolysis may be due to the accumulation of cellobiose and low activity of enzymes at 25°C. Further increase in Novozyme 188 loadings or hydrolysis may improve hydrolysis yields. A maximum of 66% theoretical ethanol yield based on initial sugar analysis of poplar was expected from these hydrolyzates if all the released sugars were fermented to ethanol. In sequential hydrolysis and fermentation with P. stipitis, 56% theoretical ethanol yields based on the initial sugar composition of poplar respectively was achieved.