Catalytic Decomposition Of H₂O₂ By Immobilized Catalase

Catalase is an oxidoreductase widely existing in the biological tissues and decomposes hydrogen peroxide to water and molecular oxygen. In the textile industry, this enzyme was mostly applied to degrade hydrogen peroxide after textile bleaching and decompose hydrogen peroxide in oxygen bleaching effluents. Many scholars both at home and broad did large numbers of studies on immobilization of catalase. They immobilized catalase on different types of supports and had different purposes. But there was a litter reports on immobilization of catalase on cotton fabric oxidized by sodium periodate and application of treat with oxygen bleaching effluents.The processes of catalase immobilized on cotton fabric were studied in the paper and the optimal condition of immobilization was obtained. On this basis the characterizations of immobilized catalase that was immobilized under optimal condition were researched. The main contents included the optimum temperature and pH, thermal stability, optional stability, storage stability and the effects of some additives on activities of immobilized and free catalases. The kinetic parameters of immobilized and free catalases were also determined further in this text. Finally, the article gave a research on treatment of oxygen bleaching effluents by immobilized catalase.The results showed that the optimal conditions for oxidation of cotton fabric were as follows: concentration of sodium periodate 0.20mol/L, oxidation time 8h, oxidation pH 6.0 and oxidation temperature 40℃. The optimum immobilization process was as follows: catalase dosage 0.20mL/g cotton fabric, immobilization time 24h. The optimum temperature of immobilized catalase was 10℃higher than that of the free enzyme. Both the immobilized and free enzymes presented their optimum pH at 7.0. Under a certain condition, the immobilized catalase was reusable. The thermal and storage stabilities and the effect of metal ions on activity of immobilized catalase were better than those of free catalase. Compared to free catalase, the K'm value of immobilized catalase increased and the immobilized catalase had less affinity toward substrate. And that the V'm value of immobilized catalase decreased. The K/S value of fabric dyed by oxygen bleaching effluents treated by immobilized catalase was very close to that of fabric dyed by fresh water. The dyeing in immobilized catalase-treated oxygen bleaching effluents resulted in smaller color difference and equal rubbing fastness compared to the dyeing in fresh water.