A robust and stable nano-biocatalyst by co-immobilization of chloroperoxidase and horseradish peroxidase for the decolorization of azo dyes

BACKGROUND Immobilization of more than one peroxidase on the same support is an ideal technology for application because such a multi-enzyme catalytic system may show high activity over a very wide optimal range of pH, temperature and H 2 O 2 concentration. In this work, chloroperoxidase (CPO) and horseradish peroxidase (HRP) were co-immobilized on ZnO nanowires/macroporous SiO 2 composite support through an in situ cross-linking method. An anionic bi-epoxy cross-linker was used by adsorption on the surface of ZnO nanowires before cross-linking. RESULTS The cross-linking was carried out under suitable conditions: pH 6.5, reaction temperature 15°C and reaction time 15 h. Using a 1/1 mixture of CPO and HRP resulted in a co-immobilized enzyme with loading 79.6 mg CPO g -1 support and 52.8 mg HRP g -1 support , and total specific activity up to 15.7 U per mg support . The co-immobilized enzyme also showed good stability after 60 days of storage, and excellent reusability over 20 repeat uses. CONCLUSIONS For the decolorization of azo dyes the co-immobilized CPO (60%)/HRP (40%) exhibited high catalytic activity over very wide ranges of pH, temperature and H 2 O 2 concentration. Using this robust biocatalyst, complete decolorizations of azo dyes have been realized within 3 h of reaction. © 2017 Society of Chemical Industry