Sustainable and energy-efficient dyeing of esterase-treated polyester with reactive dyes

Abstract

The conventional high-temperature, high-pressure (HTHP) dyeing of polyester with disperse dyes is energy-intensive (~1580 kcal/kg fabric), time-consuming, and requires specialized machinery while producing harmful, dye-laden effluents. The issue is more pronounced with polyester cotton blends, as polyester requires disperse dyeing at high temperature while cotton requires reactive dyes, both in aqueous media, necessitating separate or sequential dyeing steps that increase water, energy, and chemical consumption. This study presents a cleaner, energy-efficient alternative through the enzymatic surface modification of polyester using Esterase enzyme. The treatment introduces reactive -OH and -COOH groups, enabling dyeing with cold-brand reactive dyes, which are water-soluble, self-hydrolyzing, and require much less energy (~201 kcal/kg fabric). Treatment parameters, enzyme concentration, time, temperature, and pH, were optimized, and FTIR analysis confirmed successful functionalization. The modified polyester showed enhanced absorbency, reduced wicking height and contact angle, and better dye affinity without compromising fabric strength. Dyeing at 40-45 °C achieved 60-70% energy savings over the HTHP process. This method also eliminates the need for high-pressure machinery, reduces process complexity, and lowers effluent load due to the environmentally benign nature of reactive dyes. The dyed fabrics exhibited uniform shades, good color fastness, and moderate K/S values. Overall, this strategy supports sustainable, eco-efficient textile processing.