Synthesis of A-type carbonated hydroxyapatite (CHA) materials has typically involved heating of a hydroxyapatite composition for 24 hours or greater. In this study, a hydroxyapatite powder was heated at 800, 900 or 1000°C for 1, 8 or 16 hours in dry CO2. Samples heated for 8 and 16 hours at 900/1000°C were fully-carbonated A-type CHAs. After only one hour at 1000°C, the carbonate content approached 95% of the theoretical maximum. Preparing compositions with more than 95% of the theoretical maximum with reduced thermal energy (1000°C for 1 hour, or 900°C for 8 hours) results in powders with higher surface areas and a reduced level of sintering, compared to powders prepared with typical thermal treatments reported for A-type CHAs, such as 1000°C for 16 hours. As far as the authors are aware, these are the shortest heating times reported for the preparation of fully-carbonated A-type CHAs which is significant for future applications of such powders, particularly in applications beyond medical devices such as chromatography, remediation and carbon capture.
The authors would like to acknowledge the University of Aberdeen and the Royal Commission for the Exhibition of 1851 for providing financial support as well as Mr Colin Taylor and Mr John Still for their assistance in collecting some of the experimental data presented here.
- A-type substitution