Selective separation of precious metals using biomass materials

Proteins are known to exhibit specific interactions with various metalions. In this study, we investigated two types of protein-rich biomass, chicken feather and hen eggshell membrane, as adsorbents for separation of precious metal ions. Precious metal ions such as Au(III), Pd(II) and Pt(IV) were selectively adsorbed on the biomass in the presence of various transition metal ions. The adsorption capacity of eggshell membrane was higher than that of feather. Adsorption of Au(III) on the eggshell membrane was prominent at a pH range below 5. The adsorption behavior was explained by the complexation of Au(III) ion with proteins in the eggshell membrane and it was affected by Au(III) ion species in the feed aqueous solutions.