New method for the covalent immobilization of a xylanase by radical grafting of acrylamide on cellulose acetate membranes

This work deals with a new grafting method of acrylamide on cellulose acetate powder and flat membranes, followed by activation with glutaraldehyde in order to provide supports for the enzyme immobilization. The grafting of acrylamide was proved by FTIR and by determination of nitrogen content of the cellulose acetate material. The influence of some polymerization parameters on the grafting degrees was checked. The grafting degrees of acrylamide, on cellulose acetate flat membranes, increased almost linearly with the initiator/membrane ratio, polymerization time and monomer/membrane ratio, whereas the activation time had a more complex influence. The immobilization of xylanase was successfully occurred on the acrylamide grafted CA membranes. The bonded enzyme has shown biocatalytic activity in beechwood xylan solution, after subsequent incubations at 50 °C, lasting 7 h altogether. The immobilized enzyme was more resistant to inactivation by heat than the soluble enzyme.