Salt-free dyeing of cotton fabric modified with prepared chitosan-poly propylene imine dendrimer using direct dyes

This study presents a novel method for eco-friendly dyeing of cotton fabrics with direct dyes. Cotton fabric modified with chitosan-poly propylene imines dendrimer CS-PPI, and its dyeing and fastness properties were investigated using three direct dyes. The impacts of important factors, i.e., CS-PPI concentration, dye concentration, dyeing time, dyeing temperature, and salt concentration were investigated and optimized. Results showed that cotton treatment with optimum CS-PPI concentration 15 owf significantly improved dye up-take and decreased effective dye concentration required to obtain the more color depth. Also, optimum dyeing time and temperature were reduced ~50 and ~20˚C, respectively. Moreover, salt was eliminated from cotton dyeing process with direct dyes and “salt-free dyeing” was therefore developed. Colorimetric and color fastness data emphasized that this treatment had no negative effect on the hue and color fastness properties of dyed samples. So, it was concluded that this new eco-friendly process can help to save considerable amount of time, energy, chemicals, and dyeing costs, and also can remedy the associated dyeing effluent problems from dyeing of cotton with direct dyes.