Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Lignocellulosic biomass is composed of carbohydrate polymers (cellulose and hemicellulose) and lignin which are not readily available in their native form. It is widely accepted that lignin acts as the “glue” that binds cellulose and hemicellulose, giving both rigidity and resistance to the lignocellulosic structure. A dominant concern is the high price of enzymes and the costly pretreatments needed to achieve high sugar yields for their bioconversion into fuels and chemicals. The use of non-ionic surfactants during pretreatment can help alter the structure of lignocellulosic biomass to improve cellulose digestibility and ethanol yields. Tween 80, Tween 20, PEG 4000 or PEG 6000 was used in combination with ammonium hydroxide for the pretreatment of sugarcane bagasse. The pretreatment was carried out by mixing sugarcane bagasse, ammonium hydroxide (28% v/v solution), and water at a ratio of 1:0.5:20, adding 3% (w/w) surfactant based on the weight of dry biomass, and heating the mixture to 160°C for 1 h. Cellulose, hemicellulose and lignin compositions were determined before and after pretreatment with and without the addition of surfactants. Fibers were hydrolyzed using two concentrations of commercially available enzymes, Spezyme CP and Novozyme 188. Fermentable sugars, organic acids, hydroxy-methyl-furfural and furfurals were analyzed by HPLC. The results indicated that Tween 80 gave the highest glucose digestibility (86%) and ethanol yield (71%) as compared to the use of only dilute ammonia (45%, 42%) or water (30%, 25%) as catalysts, respectively.
Keywords: ammonia treatment, sugar cane, surfactant, ethanol, lignocellulose, biomass, hydrolysis