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

Abstract

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.

Cotton Dyeing with Vat Dyes using Alkaline Pectinase and Iron (II) Salt

“…In our earlier work, we established that alkaline pectinase can reduce sulfur dyes at 90 °C, thus proving its dye reduction abilities. 27 To develop a new enzyme-based reduction method, dyebaths were prepared with alkaline pectinase (0.25% owd) and NaOH (10% owd). Dyeings were carried out at 60 °C.…”

A review on synthesis of nitrogen-containing heterocyclic dyes for textile fibers - Part 1: Five and six-membered heterocycles

“…Soaping off, after dyeing, is significant to guarantee the highest colorfastness to washing and rubbing. Sulphur dyes are cheaper than numerous other dyes, however, the waste water from dyeing may necessitate particular treatments before discharge into waste water treatment plants [49].…”