Clark et al. (1985)
recently formulated a kinetic model for coupling restricted diffusion and immobilized reaction of enzyme molecules in a cylindrical pore using the concept of "pore central core restricted diffusion." This model takes into consideration the increase of diffusion resistance by the reduction of available cross-sectional area during the enzyme immobilization process. It successfully predicts the results of nonuniform enzyme distribution in porous supports as observed in some experiments.
Clark's model assumes that supports have uniform pore size. This is in contrast to the fact that pore size distribution exists in almost all porous solids. Treating pores of various diameters as uniform in size (e-g., average pore diameter) tends to underestimate the plugging effect of small pores by enzyme molecules during the immobilization process, especially for porous solids with broad or bimodal pore size distributions. This might result in significant deviations of the predicted values of the amount of the enzyme loaded.
The objective of this study is to improve Clark's model by incorporating a pore size distribution into the pore central core restricted diffusion model. By using a refined equation for the void cross-sectional area of pore, we recalculate the amount of enzyme immobilized vs. time on stream. In addition, a real pore size distribution of silica supports is measured to investigate the deviation of the loaded amount of enzyme predicted by Clark's model. et al. (1985) proposed a quasisteady-state model to simulate the enzyme immobilization process within a cylindrical
Mathematical Model
Clark