The Removal of Pertechnetate from Aqueous Solution by Synthetic Hydroxyapatite: The Role of Reduction Reagents and...

The use of knowledge from technetium radiochemistry (even from nuclear medicine applications) allows us to select an sorbent for ^99mTc radionuclide sorption, which is hydroxyapatite. Using radioisotope indication, the ^99mTcO₄^- sorption process on synthetic hydroxyapatite was studied by the batch method in the presence of SnCl₂ and FeSO₄ reducing agents. The complexing organic ligands' effect on the ^99mTcO₄^- sorption under reducing conditions was investigated. In the presence of Sn²⁺ ions without the addition of organic ligand, the sorption percentage reached above 90% independently of the environment. In the presence of Fe²⁺ ions without the addition of organic ligand, the sorption of ^99mTcO₄^- was significantly lower and was at approximately 6%, depending on the concentration of Fe²⁺ ions in solution. The effect of complexing organic ligands on the ^99mTcO₄^- sorption on hydroxyapatite from the aqueous solution, acetate buffer and phosphate buffer decreases in the following order for Sn²⁺: oxalic acid > ethylenediaminetetraacetic acid > ascorbic acid. In the presence of Fe²⁺ ions without organic ligands, the sorption reached up to 15% depending on the composition of the solution. The addition of oxalic acid and ascorbic acid increased the sorption up to 80%. The ethylenediaminetetraacetic acid had no significant effect on the sorption of technetium on hydroxyapatite.