Indigo Dyeing of Cotton using Alkaline Catalase and Additives

Sodium hydrosulfite is universally applied as a reducing agent for the reduction of indigo, but also produces hazardous by-products viz. sulfate, sulfite, and thiosulfate ions with harmful effects on the environment due to their toxicity, as well as corrosive effects on the waste lines. To overcome these problems, use of an ecofriendly reducing agent, viz. alkaline catalase, along with iron (II) sulfate, was used in place of sodium hydrosulfite for dyeing of cotton with indigo. Dyed samples were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The alkaline catalase with iron (II) sulfate reducing system produced the same reduction potential in dyebaths, reduction bath stability, surface color strength, and color fastness properties of dyed cotton compared to sodium hydrosulfite use.