(348f) Development and Validation of a Model for Cellulase Diffusion, Adsorption and Reaction In Wood Particle

In the pretreatment process of
biofuel production, the use of woody biomass such as hybrid poplar and lodgepole pine requires an energy
intensive size reduction step. Optimization of wood particles with respect
to specific size and shape not only reduces the energy cost for size reduction,
but also facilitates downstream biochemical conversion. Modeling enzyme
behavior in wood particles can provide useful information for wood particle
design. In this study, cellulase diffusion, adsorption, and reaction in wood
particles were modeled using simulation software "COMSOL Multiphysics".  The
model predicted that physical dimensions and vascular characteristics of the
wood particle had great influence on the enzyme diffusion into wood. The
adsorption of cellulases on cellulose and lignin also played an important role
in enzymatic hydrolysis. Experiments supporting this model comprised measurements
of enzyme and sugar concentrations both in bulk solution and inside the wood
particle. The hydrolysis experiment was carried out using a range of wood
particle sizes from 1 mm to 6 mm derived from different size reduction
approaches. The model described the enzyme and sugar concentration profiles during
hydrolysis accurately and can be used to optimize wood particle design for
pretreatment and saccharification, as well as to provide essential information
for reactor and process design of biofuel production.

Figure 1 enzyme concentration profile in 8 tracheids wood
particle model