Keratin Hydrolysate from Wool By-products as an Additive for Dyeing Bovine Leathers

In this research, the aim was to obtain keratin hydrolysate from wool waste from sheep breeders and use it in technologies for dyeing bovine hides. The keratin hydrolysate (KerNa), obtained by alkaline hydrolysis with sodium hydroxide, was physico-chemically analyzed, determining the protein substance in the amount of 80.65%, highlighting the bands specific to peptides and compounds with sulfur by FTIR spectroscopy and particle size by DLS technique, obtaining majority populations at 161 nm and 615 nm. Bovine hides were treated with keratin hydrolysate, in different stages of the dyeing process, and an increase in the dyeing resistance to wet and dry rubbing and the dyeing resistance to water drops was obtained, as well as the improvement of the specific color parameters. Leathers dyed with the use of the KerNa additive showed an increase in the friction resistance of the dyeing (grade 5/5) and brighter colors according to ISO Brightness. Treatments based on protein-rich keratin hydrolysate, applied in various stages of the dyeing process, interact with the leather's collagen or tanning agents, giving the finished leathers improved properties of shade, shine and softness. The good results obtained in the applications of keratin hydrolysate in the leather industry show that the keratin extract can be the basis for obtaining new biomaterials with various applications. The utilization of wool waste from animal husbandry leads to a decrease in the amount of waste and the prevention of environmental pollution.