The uptake of strontium by calcium phosphate phase formed at an elevated pH

The sorption of radioactive strontium by poorly crystalline hydroxyapatite (HA) obtained by the transformation of amorphous calcium phosphate (ACP) at initial pH 10.8, was investigated, Morphological analysis, performed by transmission electron microscopy, has demonstrated that the solid phase consists of nanometer size ultra-micro particles connected into spherical aggregates. A maximum sorption capacity, determined as the asymptote of the sorption isotherm was Gamma = (3.8 +/- +/- 0.3). 10(-2) mol Sr/mol P. Based on this result and the structural conditions, a possible theoretical explanation for the incorporation of a strontium ion into the apatite lattice has been proposed.