A diffusion-reaction model for alpha-chymotrypsin carrying uniform thermosensitive gel beads

In this study, the kinetic behavior of alpha-chymotrypsin-immobilized, unif orm poly(isopropylacrylamide) gel beads was investigated. The kinetic study was performed by using a continuous reactor operated at steady-state condi tions. In the experiments, substrate feed concentration, residence time, an d reactor temperature were changed. The results were explained by a diffusi on-reaction model developed for steady-state conditions. The effectiveness factor and Thiele modulus values of the thermosensitive enzyme-gel system w ere estimated at different temperatures by using an iterative procedure bas ed on fourth order Runge-Kutta algorithm. The results indicated that the ov erall hydrolysis rate was controlled by the substrate diffusion through the gel matrix. A bending point was detected for the Thiele modulus at the low er critical solution temperature (LCST) of the thermosensitive gel. The eff ective diffusion coefficient of substrate and effectiveness factor decrease d suddenly at LCST. The mass transfer process within the thermosensitive ca rrier could be described in detail by the proposed model. The results of ou r numerical procedure were also compared with an analytical approximate sol ution available in the literature. The consistency between two different mo del was reasonably good. (C) 1999 John Wiley & Sons, Inc.