Enhanced kinetic performance and stability of catalase immobilized on epoxy-functionalized kaolinite

The immobilization of catalase onto stable, reusable supports is crucial for efficient peroxide-based biocatalytic applications. In this study, catalase was immobilized for the first time onto epoxy-functionalized kaolinite particles prepared via surface silanization with (3-glycidyloxypropyl)trimethoxysilane. Structural and surface characterizations confirmed successful organosilane grafting while preserving the layered kaolinite framework. The modified support exhibited rapid enzyme uptake and a high immobilization capacity of approximately 300 mg g(-1). Kinetic analysis showed a substantial decrease in K-m from 57.3 mM (free catalase) to 21.6 mM after immobilization, indicating enhanced substrate affinity. In contrast, V-max decreased due to diffusion limitations typical of heterogeneous systems. Despite this, catalytic efficiency increased nearly 1.8-fold. Moreover, immobilized catalase demonstrated significantly improved operational reusability and long-term storage stability compared to the free enzyme. These results highlight silanized kaolinite as a robust, low-cost, and efficient mineral-based support for catalase immobilization, with strong potential for environmental and industrial biocatalytic applications.