Extracting keratin from chicken feathers by using a hydrophobic ionic liquid

Keratin was extracted from chicken feathers by using a hydrophobic ionic liquid (IL), 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([HOEMIm][NTf2]). Extracted keratin has good solubility in water while the ionic liquid is immiscible with water, and therefore the extracted keratin could be easily separated from the reaction system by water. The effects of ionic liquid, NaHSO3, reaction temperature and time were investigated and extracting conditions were optimized. The maximum yield of keratin was up to about 21% with mass ratio of feathers to NaHSO31:1 and mass ratio of feathers to ionic liquid 1:40 at 80 °C for 4 h. Moreover, there was no obvious loss in the yield after ionic liquid was reused for five batches under optimized conditions. In addition, the recovery of ionic liquid was about 95% each time. The results indicated that [HOEMIm][NTf2] was very efficient as catalyst and solvent for dissolving feathers and could be easily recovered due to its hydrophobicity.

► A hydrophobic ionic liquid [HOEMIm][NTf2] was used to extract keratin from feathers.
► There was an easy separation of extracted keratin with water after reaction.
► [HOEMIm][NTf2] could be reused and the recovery of it was about 95% each cycle.
► The extraction yield of keratin was kept the same level when ionic liquid was reused.