Dissolution and regeneration of keratin from duck feathers using N-methylmorpholine N-oxide across variable conditions

Keratin, a valuable fibrous protein found in poultry waste, holds promise for applications in bioplastics, films, and biomedical materials. The objective of this study was to develop a greener extraction route for keratin from duck feathers using N -methylmorpholine N-oxide (NMMO) and to evaluate how process parameters influence yield and structure systematically. Clean duck feathers were ground and dissolved in concentrated aqueous NMMO under controlled conditions, varying the solid-to-liquid ratio, dissolution temperature, and dissolution time. Regeneration was carried out by precipitation with water or acids (acetic, citric, sulfuric) at the keratin isoelectric point. The regenerated keratin was then recovered after precipitation, dialyzed, freeze-dried, and characterized using FTIR, solid-state ^ 13 C NMR, XRD, DSC, SEM, and elemental analysis. Optimal conditions (S/L 0.1, 110 °C, 7 h) yielded up to 48 % regenerated keratin. Keratin precipitation, particularly with citric acid, affects not only the yield but also the chemical environment of keratin, as revealed by FTIR, solid-state ^13C NMR, and XRD. Thermal and morphological analysis (TGA, DSC, and SEM) confirms that structural preservation depends strongly on process conditions. This work demonstrates a scalable, greener route to keratin recovery and provides mechanistic insight into solvent–biopolymer interactions relevant to broader biomass valorization, using a recyclable solvent system.