Tuesday, May 3, 2011
Liquidambar styraciflua L. grows as understory in the southeastern U.S. pine plantations; its carbohydrates could be converted to biofuels or biochemicals via fermentation. Prior to the fermentation step, the feedstock must be deconstructed first by pretreatment then by enzymatic hydrolysis. It is critical to articulate the pretreatment and enzymatic hydrolysis steps so that the maximum possible amounts of carbohydrates are produced. To this end, a variety of 1% sulfuric acid pretreatment conditions were tested in a non-stirred batch reactor, using ground sweetgum heartwood. Dilute acid pretreatment temperature and times, including 140 °C and 160 °C, 10, 60, and 90 min respectively, were articulated with enzymatic hydrolysis. Preliminary results showed that glucose recoveries from Accellerase® 1500 hydrolysis of sweetgum heartwood pretreated at 160 °C for 60 min was the highest (88%). Although 140°C, 90 min pretreatment conditions resulted in the highest xylose recovery during pretreatment, the enzymatic hydrolysis of the ensuing biomass was not ideal. These results indicated that better hydrolysis of hemicellulose sugars does not necessarily translate to higher enzymatic hydrolysis in sweetgum heartwood.