The Preparation Of Modified PVA/Chitosan Hybrid Beads For Catalase Immobilization

Catalase is a kind of biomacromolecule that can catalyze the decomposition of hydrogen peroxide to water and oxygen. In the textile industry, catalase has been widely used to degrade the hydrogen peroxide in the oxygen bleaching effluents. Immobilization of catalase to increase its stability has been researched by many scholars both at home and abroad. In this paper,3-aminopropyl triethoxysilane was used to modify polyvinyl alcohol (PVA) and attach–NH2on it. Then the modified PVA formed chemically crosslinked beads with chitosan with the help of glutaraldehyde. After activation, these beads were used to immobilize catalase. The process of immobilization has been optimized and the properties of immobilized catalase were investigated.Firstly, FTIR and SEM were used to characterize the support and immobilized catalase. After analysis of these FTIR and SEM, we found that the modification of PVA and immobilization of catalase were carried out successfully. The main conditions of immobilization (addition of APTES, concentration of glutaraldehyde and catalase) were studied and the optimal immobilization conditions were obtained.2mL of APTES was used to modify100mL of PVA, and5%glutaraldehyde was used to activate the carrier. The activated carriers were then used to immobilize catalase in1.25mg/mL enzyme solution at last. Compared with the control group, the activity of modified group increased about26%.Then, we compared the properties of modified group with that of control group and free catalase. The optimal temperature of control group and modified group was45℃, which was20℃higher than that of free catalase. The optimal pH of control group, modified group was pH7, which was the same as that of free catalase. The resistibility of modified group and control group to bleaching bath stabilizers, surfactants and ethanol were improved. The thermal stability, pH stability and storage stability of modified group were better than those of control group, which were better than those of free catalase. Moreover, the immobilized catalase retained more than90%of its original activity after using for9times.