Development of Protein Binder from Tannery Waste for Leather Finishing

The leather industry possesses a prominent place in the fashion industry. However, waste management during leather manufacture is a limiting factor to attaining sustainability by the industry. Tannery hair waste (byproduct of enzymatic dehairing), being a rich source of keratin, remains underutilized. Casein binders are currently used for glaze finishing, which lack sustainability and incur high costs. In the present study, an attempt has been made to extract keratin hydrolysate and use it as a sustainable binder for leather finishing. The extracted keratin hydrolysate from hair waste has been characterized using nuclear magnetic resonance and Fourier transform infrared spectroscopy. Differential scanning calorimetry and thermogravimetric analysis show that the keratin hydrolysate is thermally stable. The finished leathers, characterized for distension of grain, adhesion of finish, and fastness, are found to be within the recommended standards. Gloss, contact angle, and water vapor permeability of the leather finished with a keratin hydrolysate binder show better properties as compared to the reported values for commercial casein binders. Thus, utilizing keratin hydrolysate in leather finishing not only contributes to waste reduction but also aligns with the growing trend toward closed-loop leather processing systems and circular economy practices.