(142br) Changes in Fiber Shape and Rheology of Cellulosic Suspensions During Enzymatic Hydrolysis

The initial stage of cellulose hydrolysis, or liquefaction, is of particular importance in bioprocesses that use microorganisms to produce chemicals or fuels. A rapid liquefaction stage is desirable to reduce mixing energy input and reactor volume. During this process large changes in rheology occur that are relevant for economical scale up of the process. Slurry rheology depends not only on solids concentration but also on fiber shape, both of which change during hydrolysis. The evolution of the particle length-to-width ratio is believed to be important, but has not been extensively characterized in the literature. To probe the effect of concentration and fiber shape on rheology during hydrolysis we combine fiber length and width measurements with rapid rheology measurements based on magnetic resonance imaging. Two fiber types were used that differed in the initial average length. For both fiber types rapid changes in rheology were observed during the first ten minutes of hydrolysis. The yield stresses measured displayed good correlation with crowding numbers.