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Poster Presentation 1-17
Modeling of Dilute Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover
Byung Hwan Um, M. Nazmul Karim, and Linda L. Henk
Department of Chemical and Bioresource Engineering Colorado State University 100 Glover Building Fort Collins, CO 80523
Telephone: (970) 491-1188; E-mail: byung@engr.colostate.edu
Dilute acid pretreatments at moderate temperatures using either sulfuric or phosphoric acid were used for converting lignocellulosic biomass, including the hemicellulose fraction, to soluble sugars, followed by enzyme-catalyzed hydrolysis of the cellulosic fraction to glucose. Enzymatic hydrolysis may be improved by using a surfactant to swell the cellulosic fraction to glucose. This reagent enhances the accessibility of the cellulose to enzymatic attacks, and thus improves overall economics of the process. The batch pretreatments of corn stover were carried out at 121ºC, 0~2 % (w/v) acid concentration, with residence times of 30, 60, and 120 minutes.
Dilute acid pretreated corn stover was treated with Tween 80 with concentrations ranging from 1~10 % (w/v). The treated material was tested by an enzymatic-digestibility procedure along with an untreated control sample. The dilute acid treatment proved to be a very effective method in terms of hemicellulose recovery and cellulose digestibility. Hemicellulose recovery was 65-90% and enzymatic digestibility of the cellulose in the solid was more than 80%. In sulfuric acid prehydrolysis, hemicellulose conversion and cellulose digestibility were significantly higher than those obtained in phosphoric acid. Enzymatic hydrolysis using surfactant produced 10~20 percent more sugar than without surfactant. It also confirms that high saccharification yields can be achieved when the acid-insoluble content (i.e. 1 % cellulose loading) is low.
Mathematical models describing the acid pretreatment and the enzymatic hydrolysis were developed for batch operation. The models were validated by experimental results. Models incorporate glucose and cellobiose inhibition during the saccharification process.
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