3.3. Recycle of ionic liquid
Even though previous works have demonstrated the dissolution
of feathers in ionic liquids, there is yet no effective way to
separate the protein from ionic liquids. Therefore, the reusability
of ionic liquid [HOEMIm][NTf2] was investigated under the optimum
conditions mentioned above. In our study, extracted keratin
has good solubility in water, while [HOEMIm][NTf2] is immiscible
with water. Consequently, keratin could be easily separated from
the reaction mixture by water, and the extracted keratin could
be purified by dialysis and precipitated by ethanol according to
requirement of final product. The remaining ionic liquid could be
used directly in the next time. As shown in Fig. 2, the ionic liquid
was used forfive batches without essential loss inthe process of dissolving
feathers. It was also found that the recovery of ionic liquid
was about 95% in each cycle. This indicated that [HOEMIm][NTf2]
is an effective hydrophobic ionic liquid for extracting keratin from
chicken feathers.