Abstract
The application of the enzyme catalase in the textile bleaching process requires the use of catalase under high-temperature, alkaline conditions. We therefore investigated the immobilization of catalase on calcined montmorillonite and pillared interlayer clays (PILCs) as a means of increasing the enzyme’s temperature and pH stabilities. SiO2－PILCs and Al2O3－PILCs were prepared from montmorillonite and were calcined at 400 or 600 ℃. The temperature stability of catalase immobilized on the clays was higher than that of free catalase up to 55 ℃. Additionally, the pH at which the catalase immobilized on the two PILCs was stable was shifted to more alkaline values compared to the pH values for free catalase. In particular, the relative activity (with 100% activity being defined as that observed at pH 7) of catalase immobilized on Al2O3－PILCs was higher than that of free catalase at pH 8–12. Furthermore, the relative activity at pH 10–11 of catalase immobilized on Al2O3－PILCs calcined at 600 ℃ was only 40–60% of that observed at pH 7 for the same PILC. However, the relative activity of catalase immobilized on calcined montmorillonite was almost the same as that of free catalase at pH ＞7.
