Analytical Sciences

Adsorption of Divalent Transition Metal Ions with a Chelating Agent on Octadecyl Silica Gel

Masamitsu IIYAMA,* Syunichi OSHIMA,* Hisao KOKUSEN,* Masami SEKITA,** Shigekazu TSURUBOU,*** and Yu KOMATSU*

*Department of Environmental Chemistry, College of Environmental Engineering and Architecture, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501, Japan
**National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
***Department of Chemistry, School of Dentistry, Asahi University, 1851 Hozumi, Hozumi-cho, Motosu-gun, Gifu 501-0296, Japan

This investigation looked at the extraction ability of divalent transition metal ions onto an octadecyl silica gel (C18g) with a 4,4-trifluoro-1-(2-thienyl)-1,3-butadione (TTA) chelating agent. A method of retaining TTA onto C18g (TTA-C18g) was developed in order to adsorb the metal ions. The difference in the half-adsorption and half-extraction pH values between transition metals Ni²⁺-Co²⁺ was found to be 0.7 in this system. This is better than previously published results of 0.3 for the conventional extraction method using TTA in nitrobenzene. More than 96% of the metal ions in aqueous solution could be adsorbed onto TTA-C18g. Our system, which has no organic phase, can achieve a better removal or separation of transition metal ions than the conventional solvent-extraction methods using TTA in toluene or nitrobenzene.

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