Cotton Dyeing with Sulfur Dyes using Alkaline Enzymes as Alternate Reducing Systems

Sulfur dyes are water insoluble and require reduction as well as solubilization before application. These dyes are used for dyeing cotton with heavy shades, primarily because of good light and wash fastness at low cost. Sodium sulfide used for reduction is highly toxic, releasing sulfur products in drained out liquor, including hydrogen sulfide gas. Enzymes capable of reducing sulfur dyes were studied to replace sodium sulfide in dyebath formulations. It was found that a few enzymes viz. protease, pectinase, lipase, and catalase can effectively reduce all sulfur dyes. Dyebath potential, color strength ( K/ S), reduction bath stability, and colorfastness of dyeing were comparable among the reducing systems, thus demonstrating the feasibility of enzymatic cotton dyeing with sulfur dyes.