ADSORPTION OF CO2 ON NONSTOICHIOMETRIC STRONTIUM CALCIUM HYDROXYAPATITES

Colloidal particles of homogeneous solid solutions of strontium and ca lcium hydroxyapatites (SrCaHAP) have been synthesized in different mol e fractions, Sr/(Ca + Sr) ranging from 0 to 1. The crystallite size of the SrCaHAP particles obtained was a minimum around Sr/(Ca + Sr) = 0. 3, whereas the specific surface area was maximum around the same Sr/(C a + Sr). The morphology of the SrCaHAP particles became irregular as S r/(Ca + Sr) increased up to 0.5. The irreversible adsorption of CO2 pe r unit surface area was a minimum at (Ca + Sr)/P = 1.56, less than the stoichiometric value of 1.67 These results suggest that there are two kinds of irreversible adsorption site for CO2 on SrCaHAP.