A New Approach to Eco-friendly Dyeing of Cotton Fabric with Vat Dyes Using Plant Extract as Natural Reducing Agents

Vat dyes are one of the most popular dye classes producing brilliant hues on cellulose, viscose, and linen fabrics. Conventional vat dyes, to be converted into watersoluble leuco form, involve reduction with sodium dithionite which produces lots of harmful and nonrenewable biproducts that causes environmental pollution. In this research work, apple, henna root, cabbage stem and amaranthus root have been used as organic reducing agents and compared with sodium dithionite in vat dyeing on cotton fabrics. Fruit extract (apple) and three plant extracts can pave a new way in the reduction process of vat dyes. Here reduction potential of reducing agents has been measured using a potentiometer coupled with photometric study and FTIR analysis has also been determined prior dyeing. The concentrations of reducing agents were noted to reach the required reduction potential which needs to be more negative than the range of 700 to 850 mV (vs. Ag/AgCl, 3M KCl) for reducing vat dye. The color strength of the dyed samples was analyzed by a Reflective Spectrophotometer and several colorfastness tests were also performed. The results show that using natural reducing agents in the reduction of vat dye can be appreciated because test results are closer to reduction with sodium dithionite. Furthermore, with introducing these substances, the production of hazardous chemicals is minimized and vat dyeing can be environmentally friendly.