Analytical Sciences

Multielemental Elution Behavior of Metal Ions Adsorbed on Iminodiacetic Acid Chelating Resin by Using Hydrogen Peroxide as an Eluent

Tomoki YABUTANI,* Hidehiko SUMI,** Takamasa NAKAMURA,** Shinsuke AKATSUKI,** and Le Thi Xuan THUY**

*Department of Life System, Institute of Technology and Science, The University of Tokushima, 2-1 Minamijosanjima, Tokushima 770-8506, Japan
**Department of Earth and Life Environmental Engineering, Graduate School of Advanced Technology and Science, The University of Tokushima, 2-1 Minamijosanjima, Tokushima 770-8506, Japan

In the present work, we investigated the multielemental elution behavior of metal ions absorbed on iminodiacetic acid (IDA) chelating resin by using hydrogen peroxide (H₂O₂) as an eluent. As a result, V(V), Mo(VI), W(VI), Nb(V) and Ta(V) were efficiently eluted by H₂O₂. In contrast, other metal ions were rarely recovered. The oxidation states of V(V), Mo(VI), and W(VI) were not changed through the H₂O₂ eluting process, checked by X-ray photoelectron analysis. In addition, the UV-vis adsorption spectra and IR spectra of V(V), Mo(VI) and W(VI) in the H₂O₂ eluent suggested the formation of metal-peroxo complexes through H₂O₂ elution. The desorption of these metal ions from IDA functional groups is explained in term of destabilization along with the coordination of peroxo-ligands to the V(V)-, Mo(VI)- and W(VI)-IDA complexes, and a decrease in the adsorption capacity by electrostatic repulsion between dissociated carboxylic groups of IDA and the oxoanions in the neutral pH shown in 30 wt% H₂O₂. When this method was applied to the selective separation of V(V), Mo(VI) and W(VI) from other metals in an acid soluble fraction of fly-ash, 83.4 ± 2.5% of V(V), 88.1 ± 3.3% of Mo(VI), and 69.3 ± 5.4% of W(VI) were recovered in a 30 wt% H₂O₂ eluent.

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