Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
The concept of reaction severity, which combines residence time and temperature, is often used in the biofuels and pulp and paper industries. The influence of the severity of dilute acid pretreatment on the subsequent enzymatic hydrolysis of soluble oligomer-derived and insoluble cellulose-derived glucose using a commercial enzyme preparation (from Novozymes) was investigated. A dilute acid pretreatment was performed at 0.7 % H2SO4 (w/v) and 1% solid concentration with a 100 mL Accelerated Solvent Extraction (ASE, Dionex Corp.). Hydrolysis kinetics were analyzed using a Yellow Springs Instruments (YSI Corp.) glucose analyzer. The pretreatment conditions (residence time, temperature) with constant acid concentration were varied over a range of reaction severities. Enzyme kinetics were measured at different dilutions of biomass hydrolysate, with all three sources of biomass causing inhibition of the enzymes to different degrees. It was noted that the presence of soluble oligomers in the hydrolysate resulted in apparent diminution of the inhibitory effect, resulting from an increased release of oligomer-derived glucose at higher concentrations of hydrolysate. Correction for this glucose contribution from the oligomeric sugars rendered the inhibitory effect of the hydrolysate more apparent.
Analytical interrogation of the hydrolysates quantified 40 different compounds present in the hydrolysates. Comparison of analytical to hydrolysis results indicate that enzyme inhibition can be correlated to the presence of select degradation compounds present in the hydrolysate.