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Wool keratin, a natural biopolymer, is potentially an important renewable source of raw materials for the polyamide plastics industry. Large quantities of non-spinnable and short fibers of wool are discarded globally and hence are available as low value waste materials. In this study, we have investigated different solvents, including ionic liquids and deep eutectic mixtures, for the dissolution and processing of wool. The results show that substantial dissolution of wool (up to 475 mg wool per gram of solvent) can be obtained in the 1-allyl-3-methylimidazolium dicyanamide [AMIM][dca] ionic liquid at 130 °C. Our studies also indicated enhanced dissolution (an additional 50-100 mg g-1) of wool upon the addition of a reducing agent to the ionic liquids. Water insoluble fractions (20-40%) were obtained on the addition of water to the dissolved wool. This regenerated fraction was characterized for structural and chemical changes and found to contain a larger fraction of β-sheets and random coils than the starting material. The water soluble fraction was characterised and the results indicated the presence of fragments of low molecular weight polypeptide chains. [ABSTRACT FROM AUTHOR]

• BAILs were used as a medium solvent to dissolve rice husk and depolymerize the lignin. • 78 % of regenerated lignin was effectively extracted from rice husk by [C 3 SO 3 HMIM]Cl. • Acidic properties of BAILs improve the delignification process. • [C 3 SO 3 HMIM][HSO 4 ] was successfully depolymerized the lignin into low molecular weight aromatic products. Lignocellulosic agricultural waste, like rice husk, is generated abundantly from rice milling industries. It is no longer mere waste but has become a treasure trove of outstanding potentials for sustainable environment growth. In this study, a series of Bronsted acidic ionic liquids (BAILs) were synthesized, characterized and used as a medium solvent to dissolve rice husk. Fractionation of rice husk into lignin, cellulose and hemicellulose was successfully achieved after 6 h of stirring at 100 °C. About 78 % and 53 % of the regenerated lignin were effectively extracted from rice husk by 1-methyl-3-(3-sulfopropyl)-imidazolium chloride, [C 3 SO 3 HMIM]Cl and 1-methyl-3-(3-sulfopropyl)-imidazolium acetate, [C 3 SO 3 HMIM][Ace] respectively, while 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate, [C 3 SO 3 HMIM][HSO 4 ] only extracted 11 % (based on the original rice husk). The regenerated lignin and cellulose were characterized using FTIR and TGA. Among the BAILs, [C 3 SO 3 HMIM]Cl was found to be a good medium solvent to extract lignin from rice husk and could be recycled up to four times. The regenerated lignin was further depolymerized using the synthesized BAILs at 120 °C (1 h) to generate low molecular weight aromatic products, which were analysed using gas chromatography-mass spectrometry (GC–MS). During depolymerization process, [C 3 SO 3 HMIM][HSO 4 ] was identified as an excellent solvent to depolymerize the lignin into low molecular weight aromatic products. [ABSTRACT FROM AUTHOR]