Sustainable valorization of tannery hair waste into keratin by an acoustic cavitation-assisted process using a green solvent

Abstract Keratin, a valuable biomaterial from tannery hair waste, has potential for biomedical applications due to its inherent biocompatibility, and biodegradability. This investigation deals with eco-efficient acoustic cavitation assisted method for extraction of keratin from tannery animal hair waste using ionic liquid [BMIM]Cl. Here, ionic liquid has been used as a solvent for better keratin recovery. Optimizing parameters such as solid-to-liquid ratio, acoustic irradiation time, and power, achieved a 71% keratin yield and a 95% reduction in reaction time, mitigating environmental impact and facilitating a cleaner, faster and more sustainable process. The extracted keratin's structural integrity and intactness were substantiated by ATR-FTIR and solid-state ¹³C NMR spectroscopy. Additionally, CD analysis revealed the presence of α-helix and β-sheet structures of keratin. XRD analysis confirmed the keratin's crystallinity, while DSC and TGA thermograms proved its thermal stability. FE-SEM studies elucidated the morphological features. Furthermore, the ionic liquid was successfully recovered from the effluent, and NMR studies confirmed its intact chemical structure, suggesting its potential for industrial applications. The process contributes to resource efficiency, waste minimization, and the development of sustainable materials from industrial residues.