The surfaces of calcium hydroxyapatite (CaHAP) particles with different Ca/P atomic ratios, synthesized by the precipitation method, were characterized and the adsorption mechanism of CO 2 on CaHAP at 25 °C was elucidated mainly by FTIR. The number of surface P−OH groups was maximum at Ca/P = 1.6 while the quantity of irreversibly adsorbed CO 2 was minimum at the same Ca/P. This indicates that the surface P−OH groups not only are the reversible adsorption sites for CO 2 but also interfere with the irreversible adsorption of CO 2 . IR bands due to H 2 O and CO 3 2 - appeared on CO 2 adsorption and were intensified by increasing the adsorbed amount. The physisorbed CO 2 was converted into CO 3 2 - ions with the course of time. These results demonstrated that the irreversible adsorption of CO 2 progresses via the reaction of CO 2 with surface OH -: 2OH - + CO 2 → CO 3 2 - + H 2 O.
No takes yet. Share an insight, caveat, or question.
Cheng et al. (1998) studied this question.
Synapse has enriched 4 closely related papers on similar clinical questions. Consider them for comparative context: