Analytical Sciences

Direct Evidence for Two Interaction Modes in Adsorption of Divalent Metal Ions to Iminodiacetate-Type Chelating Resins

Akio YUCHI,  Kouichi MUKAIE, Yuka SOTOMURA, Hiromichi YAMADA, and Hiroko WADA

Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan

The adsorption curves of divalent metal ions (M²⁺) to an iminodiacetate(IDA)-type chelating resin (-L^2-) under the condition of metal ions in excess against IDA groups clearly indicated the difference in contribution between two species. Copper and nickel are adsorbed only as [(-L)M^II], while cadmium and calcium are adsorbed as [(-L)M^II] and [(-LH)₂M^II]. Addition of salts may enhance the deprotonation of IDA groups, interfere with the adsorption as [(-LH)₂M^II], and yield remarkable changes in adsorption curves, depending on the metal ions.

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