Sorption of Co2+, Pb2+, and Sr2+ Ions on Hydroxyapatite, Synthesized in the Presence of Oxyethylidenediphosphonic Acid

Abstract

The physicochemical and sorption properties of hydroxyapatite synthesized in the presence of oxyethylidenediphosphonic acid, as crystallization inhibitor, were studied. The effect of acid concentration and calcium phosphate reagents was established on the sorption properties of hydroxyapatite with respect to ions Co²⁺, Pb²⁺, and Sr²⁺. It was shown that the sorption capacity of amorphous hydroxyapatite obtained in the presence of 1.0 mol % oxyethylidenediphosphonic acid, for Co²⁺ and Sr²⁺ ions, increases by 2–2.5 times, and for Pb2+ ions, by 4–5 times compared to crystalline hydroxyapatite obtained without acid additives. It was revealed that the observed differences in the sorption capacity of amorphous and crystalline hydroxyapatite with respect to the studied metal ions are due to different mechanisms of their adsorption.