The Addition of Water to Extract Maximum Levoglucosan from the Bio-oil Produced via Fast Pyrolysis of Pretreated Loblolly Pinewood

Levoglucosan is one of the major polar compounds that can be initially extracted into an aqueous fraction with water as the solvent. Levoglucosan can be hydrolyzed by an acid catalysis into monomeric sugars (primarily glucose), which can be further converted biochemically into alcohols or lipids, or converted catalytically into hydrogen. It has been demonstrated that the levoglucosan yield can be greatly increased if the proper pretreatment is applied to demineralize the feedstock prior to pyrolysis. In this study, bio-oil with a high levoglucosan concentration was produced via the fast pyrolysis of a dilute acid pretreated loblolly pine wood in an auger reactor. The water-to-bio-oil ratio, temperature, and time were selected as the three parameters to investigate the optimal condition for extracting the maximum amount of levoglucosan from the bio-oil. A response surface design (Box Behnken Design) was utilized to determine the direct and interactive effects of the three parameters on the extraction yield of the levoglucosan from the bio-oil. The optimal condition for the levoglucosan extraction was found to be 1.3:1 (water-to-bio-oil ratio), 25°C, and 20 min, with a levoglucosan yield of 12.7 wt%.