under magnetic stirring condition. After desired time, the residual
solids were removed by suction filtration immediately under the
high temperature because the increase of viscosity with decreasing
temperature will cause difficulty in filtration. Then, the keratin
solution was added with some water at room temperature to precipitate
keratin. The solid keratin and liquid phase were separated
by suction filtration. IL was recovered from the liquid IL–water
phase by evaporating water, and it can be used repeatedly.