REACTION ENGINEERING STUDY ON THE CATALYST ACTIVITY OF immobilized biocatalysts

点击翻译按钮获取中文摘要

Investigation of the influence of intraparticle mass transfer was carried out using immobilized microorganisms and immobilized plant cells entrapped in Ca-alginate gel particles. Baker's yeast and Zymomonas sp. were used as microorganisms and Papaver somniferum was used as a model of plant cells.1. The influence of mass transfer was studied using immobilized resting yeast and immobilized growing yeast. In the latter case. the inhomogeneous cell distribution in the carrier was observed. Effective diffusivity in the gel holding cells was measured and correlated by the random pore model taking account of the decrease of effective diffusion area caused by the cells. The reaction rate of ethanol production was obtained using free cells. Combining the effective diffusivity and the reaction rate, the overall reactivity of the immobilized yeast was calculated. The calculated value coincided with the experimental data. The overall reaction rate decreased due to the large diffusion resistance when the cell concentration in the carrier increased.2. A similar approach was applied to study the behavior of immobilized resting Zymomonal mobilis. The effectiveness factor was obtained from the overall reaction rate. The inherent reaction rate of the cells was found to be about 80% of that of the free cells.3. The analysis was again carried out for the case of immobilized plant cells. The biotransformation of codeinone to codeine was investigated using immobilized Papaver somniferum. The repeated use of the biocatalyst resulted in the decrease of the activity. although the initial reactivity of the immobilized cell was almost identical with that of the free cells. According to the analysis of the diffusion behavior of substrates. the oxygen transfer was found salient to the stability of the immobilized plant cells.