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

Abstract

In this study, the kinetic behavior of α-chymotrypsin-immobilized, uniform poly(isopropylacrylamide) gel beads was investigated. The kinetic study was performed by using a continuous reactor operated at steady-state conditions. In the experiments, substrate feed concentration, residence time, and reactor temperature were changed. The results were explained by a diffusion-reaction model developed for steady-state conditions. The effectiveness factor and Thiele modulus values of the thermosensitive enzyme-gel system were estimated at different temperatures by using an iterative procedure based on fourth order Runge-Kutta algorithm. The results indicated that the overall hydrolysis rate was controlled by the substrate diffusion through the gel matrix. A bending point was detected for the Thiele modulus at the lower critical solution temperature (LCST) of the thermosensitive gel. The effective diffusion coefficient of substrate and effectiveness factor decreased suddenly at LCST. The mass transfer process within the thermosensitive carrier could be described in detail by the proposed model. The results of our numerical procedure were also compared with an analytical approximate solution available in the literature. The consistency between two different model was reasonably good.