CONTINUOUS PH MONITORING DURING PRETREATMENT OF YELLOW-POPLAR WOOD SAWDUST BY PRESSURE COOKING IN WATER

Yellow poplar wood sawdust consists of 41% cellulose and 19% hemicellu lose. The goal of pressure cooking this material in water is to hydrat e the more chemically resistive regions of cellulose in order to enhan ce enzymatic conversion to glucose. Pretreatment can generate organic acids through acid-catalyzed degradation of monosaccharides formed bec ause of acids released from the biomass material or the inherent acidi ty of the water at temperatures above 160 degrees C. The resulting aci ds will further promote the acid-catalyzed degradation of monomers tha t cause both a reduction in the yield and the formation of fermentatio n inhibitors such as hydroxymethyl furfural and furfural. A continuous pH-monitoring system was developed to help characterize the trends in pH during pretreatment and to assist in the development of a base (2. 0 M KOH) addition profile to help keep the pH within a specified range in order to reduce any catalytic degradation and the formation of any monosaccharide degradation products during pretreatment. The results of this work are discussed.