Extraction of noble metal ions from aqueous solution by ionic liquids

Nine ionic liquids containing pyridinium, pyrrolidinium and piperidinium cations with anion bis(trifluoromethylsulfonyl)imide were synthesized to investigate the ability of ionic liquids to extract silver, palladium, or gold metal ions from water at room temperature. Results are reported for distribution coefficients and extraction percentages with these ionic liquids. Ionic liquids containing a disulfide group or a nitrile group exhibit good extraction properties for silver or palladium ions. Gold ions were efficiently and selectively extracted with these functionalized ionic liquids. The influence of the mass ratio of water to ionic liquid on distribution coefficient or extraction percentage for aqueous gold ions was evaluated.

► Nine ionic liquids were synthesized to investigate extraction for noble metal ions from aqueous solution.
► Functionalized ionic liquids exhibit high extraction properties for silver, palladium, or gold ions.
► Ionic liquids containing a disulfide group, an alkenyl group, or a nitrile functional group exhibit good selective extraction for gold.