Persimmon peel gel for the selective recovery of gold

The use of persimmon peel gel for the recovery of Au(III) from aqueous chloride medium was investigated. By comparing with the adsorption of some other metal ions, the gel was found to be selective only for Au(III). The XRD analysis and the digital micrograph of the gel taken after adsorption supported the formation of gold particles during adsorption process. High selectivity and capacity of the gel for Au(III) is associated with the reduction of Au(III) to elemental form. Comparative study of reduction of Au(III) by typical tannin rich materials, green tea and oolong tea, and by various organic acids clarified the involvement of polyphenolic groups in the reduction of Au(III) during adsorption. Innovative use of this novel adsorption gel can fulfill the need of cost effective and environment friendly mean for the recovery of valuable metals.