Dyeing and Functionalization of Wool Fabric with Alizarin Red S via Covalent Combination Catalyzed by Horseradish Peroxidase and Hydrogen Peroxide

Metal ion mordants are commonly used in the process of dyeing natural fabrics, such as cotton, wool, and silk, to improve their color fastness, but the use of metal salts results in toxic metal wastes which can harm the environment and are costly to process. This study investigated the dyeing and functionalization of wool fabrics with Alizarin Red S (ARS), catalyzed by horseradish peroxidase (HRP) and H₂O₂, as well as the polymerization mechanism of the ARS/HRP-H₂O₂ system and possible covalent conjugation mechanisms with wool fiber proteins. The dyeing process was optimized by determining the effects of HRP and ARS dosages, reaction temperature, and reaction time on ARS dyeing performance, as well as the color fastness and antibacterial properties of the resulting dyed fabrics. The HRP and H₂O₂ catalyzed polymerization of ARS and covalent attachment of the polymers to the wool fibers resulted in dyed fabrics with high color fastness; the rubbing and washing fastness were both 4–5. The antibacterial properties of dyed wool fabrics were excellent, achieving 92.3% growth inhibition of Escherichia coli. Therefore, the HRP-H₂O₂ system has great potential to replace metal mordants in the dyeing process of natural fibers and reduce the production of toxic wastes by this industry.