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 Km from 57.3 mM (free catalase) to 21.6 mM after immobilization, indicating enhanced substrate affinity. In contrast, Vmax 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.