Decolorization of reactive dyes by immobilized laccase

Immobilization of laccase by Trametes versicolor on silica chemically modified with imidazol groups, amberlite IRA-400, glass-ceramic chemically modified with carbodiimide/glutaraldehyde and by aminoprolyltriethoxysilane/glutaraldehyde and montmorillonite modified by aminoprolyltriethoxysilane/glutaraldehyde were afforded. These supports were used in the decolorization of textile reactive dyes (Remazol Brilliant Blue R, Remazol Black B, Reactive Orange 122 and Reactive Red 251). One of the most efficient supports was studied in a more detailed way, silica modified by imidazole SiIm led us to obtain almost total immobilization of laccase at contact times lower than 45 min. The immobilized laccase showed high decolorization efficiency toward aqueous solutions of the dyes. In the first stages of the process, the decolorization is mainly due to adsorption of the dyes onto the support surface. However, when working in a successive dye addition system, the adsorption capacity of the supports decrease (saturation) and the enzymatic decolorization process is clearly evidenced. The use of a brief photochemical pre-treatment permitted a significantly increase on the efficiency of the enzymatic decolorization process. (C) 2002 Elsevier Science B.V. All rights reserved.