Selective extraction of copper, mercury, silver, and palladium ions from water using hydrophobic ionic liquids

Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium[4MOPYR](+), 1-methyl-1-octylpyrrolidinium[MOPYRRO](+), or 1-methyl-1-octylpiperidinium[MOPIP](+) and anions tetrafluoroborate[BF4](+), trifluoromethyl sulfonate[TfO](+), or non-afluorobutyl sulfonate[NfO](+). Ionic liquids containing octylpyridinium cations are good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. When these liquids contain a disulfide functional group, they are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.