Utilization of keratin hydrolysate of wool waste fiber for free-salt dyeing of viscose fabric

Viscose dyeing is one of the major pollutants of water due to the large amount of salt in the dyeing effluent. This study paves the way for improving environmentally sustainable wool waste and highlights a promising invaluable application through salt-free viscose dyeing. The keratin hydrolysate (KH) was obtained using microwave (MW) alkaline hydrolysis then applied on the viscose fabric in the finishing bath formulation using the pad-cure technique. The rheology of the hydrolyzed wool fibers and the amino acids composition using high-performance liquid chromatograph (HPLC) was estimated; furthermore, the fourier transform infrared spectroscopy (FTIR) of freeze-drying keratin hydrolysate was evaluated. Microwave-assisted keratin hydrolysis leads to the breakdown of peptide bonds and the release of low molecular weight proteins and peptides. The color strength (K/S) of the dyed post-finished viscose fabric increased 75% compared with that dyed by conventional technique. FTIR, scanning electron microscopy (SEM) and energy disperse x-ray spectroscopy (EDX) demonstrated and confirmed the effective finishing of keratin hydrolysate. The tensile strength and elongation of viscose fabric did not change after finishing with KH, while the air permeability improved and the light fastness properties for the modified viscose fabrics.