Abstract: A method of removing a heavy metal from a composition comprises: (1) providing a fibrous protein fiber; (2) agitating the fibrous protein fiber; (3) making a slurry of the agitated fibrous protein fiber; (4) contacting the agitated fibrous protein fiber slurry with a composition containing a heavy metal ion or a heavy metal ion complex; and (5) filtering a supernatant produced in step (4) to remove the heavy metal from the composition. The fibrous protein of the fibrous protein fiber can be selected from the group consisting of keratins, collagens, fibrins, and elastins. Typically, the fibrous protein of the fibrous protein fiber is a keratin.