Enhancement of dye absorption of cotton fabric through optimization of biopolymer treatment

Abstract

Environmental pressure is pushing towards the ‘green’ alternatives to synthetic or petro-chemically derived products. Biopolymers are replacement materials suitable for different chemical processes. The surface modification of textile fibres using biopolymers is considered as the best route for modern textile treatments, to minimize the generation of wastewater containing salts, unfixed dye and other chemicals, which may affect the environment and human health. To avoid these problems, the pretreatment of cotton with biopolymers is a safe option in eco-friendly dyeing. In the present work, chitosan was selected for application on cotton textile for improving its dyeing efficiency with natural dye (onion skin). Chitosan is a versatile polycationic polysaccharide possessing hydroxyl and amino functional groups, which can easily be fabricated with desired functional properties. The chitosan treatment was standardized on the basis of dyeing properties, such as percent dye absorption, colour strength (K/S) and wash fastness. When the chitosan treatment was applied with optimized parameters, it was found that the chitosan treated onion skin dyed fabric showed higher dye absorption (66.17%), colour strength (16.52) and wash fastness rating than the alum treated dyed fabric. Thus, the chitosan treatment enhanced the dyeing properties of cotton fabric towards the application of natural dye (onion skin), without using any metallic salt. To conclude, the chitosan treatment is a safe and environmentally benign route to improve the natural dye absorption of cotton fabrics.