Analytical Sciences

Organic-solvent/Water/Ionic-liquid Triphasic System for the Fractional Extraction of Divalent Metal Cations

Takeshi TAKATA* and Naoki HIRAYAMA**

*Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
**Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan

A novel cyclohexane/water/ionic-liquid (1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF₆]) triphasic extraction system was studied for a possible fractional extraction of divalent metal cations with co-using 8-quinolinol (HQ) and tri-n-octylphosphine oxide (TOPO) as competitive extractants. In this system, Ni²⁺ was extracted into the [bmim][PF₆] phase as a Q⁻-complex, whereas each of Mn²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ was extracted into the cyclohexane phase as an ion-pair of a cationic TOPO-complex and PF₆⁻. A suitable selection of extractants and ionic liquid can result in developing a powerful triphasic fractional extraction system.

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