Features of sorption binding of Y³⁺ ions with hydroxyapatite of various textural organization

The parameters of the sorption of yttrium ions on hydroxyapatite samples of various textural organization, viz., lamellar nanoparticles (HAPn) and porous microparticles synthesized by the enzymatic method (HAPe), were studied. The values of the maximum amount adsorbed are shown to be higher in the case of HAPe, while the sorption process is faster in the case of HAPn. The sorption kinetics is well described by a pseudo-second-order model. The kinetics of isotope exchange between sorbed and dissolved yttrium was studied by the method of radioactive indicators using the 90Y label. The exchange proceeds in several stages, at the first of which the available yttrium is exchanged from the sorbent surface. In the case of HAPe, a slow stage of yttrium exchange is observed apparently related to the yttrium located in the pore space of microparticles.