Kinetic modeling of rapid enzymatic hydrolysis of crystalline cellulose after pretreatment by NMMO.

Pretreatment of cellulose with an industrial cellulosic solvent, N-methylmorpholine-N-oxide, showed promising results in increasing the rate of subsequent enzymatic hydrolysis. Cotton linter was used as high crystalline cellulose. After the pretreatment, the cellulose was almost completely hydrolyzed in less than 12 h, using low enzyme loading (15 FPU/g cellulose). The pretreatment significantly decreased the total crystallinity of cellulose from 7.1 to 3.3, and drastically increased the enzyme adsorption capacity of cellulose by approximately 42 times. A semi-mechanistic model was used to describe the relationship between the cellulose concentration and the enzyme loading. In this model, two reactions for heterogeneous reaction of cellulose to glucose and cellobiose, and a homogenous reaction for cellobiose conversion to glucose was incorporated. The Langmuir model was applied to model the adsorption of cellulase onto the treated cellulose. The competitive inhibition was also considered for the effects of sugar inhibition on the rate of enzymatic hydrolysis. The kinetic parameters of the model were estimated by experimental results and evaluated.