A New Pb 2+ Ion-selective Hybrid Cation-exchanger — EDTA–Zirconium Iodate: Synthesis,Characterization and Analytical Applications

Abstract

An amorphous sample of the new hybrid cation-exchanger EDTA–zirconium iodate was synthesized by the combination of the inorganic ion-exchanger zirconium iodate with the organic EDTA molecule, thereby providing a new class of organic–inorganic hybrid ion-exchangers with better mechanical and granular properties, good ion-exchange capacity (e.g. 2 mequiv Na⁺/g dry exchanger), good reproducibility, a higher stability and demonstrating selectivity towards heavy metal ions.

The physicochemical properties of this material were examined by instrumental analyses, viz. FT-IR spectroscopy, X-ray diffraction studies and TGA/DTA investigations. Assessments of the elution and distribution behaviour were made and pH titrations undertaken to obtain an understanding of the ion-exchange behaviour of the material. On the basis of the distribution studies, the material was found to be highly selective towards the Pb²⁺ ion, a highly toxic environmental pollutant. Its selectivity was assessed by examining its use for some important binary separations such as Mg²⁺–Pb²⁺, Cd²⁺–Pb²⁺, Hg²⁺–Pb²⁺, Zn²⁺–Pb²⁺, Cu²⁺–Pb²⁺ and Al³⁺–Pb²⁺ on a packed column of the material. The practical potential of EDTA–zirconium iodate was explored by separating Mg²⁺ and Al³⁺ ions quantitatively from a commercially available pharmaceutical formulation, viz. Digene.01.