Utilisation of carbon dioxide in the synthesis of multifunctional AB-type carbonated hydroxyapatite compositions

Abstract

Carbon dioxide utilisation is a rapidly growing field that aims to reduce the magnitude of anthropogenic greenhouse gas emissions by using CO2 captured from point sources in the production of useful materials. AB-type carbonated hydroxyapatites containing 2.28–10.35 wt% of carbonate were synthesised in this work via aqueous precipitation reaction, with carbonate ions introduced by bubbling CO2 gas into water used in the reaction. Analysis of FTIR spectra demonstrated that carbonate ions had substituted onto both hydroxyl and phosphate sites. An AB-type carbonated hydroxyapatite with a carbonate content of 14.68 wt% was obtained after an hourlong heat treatment in dry CO2 at 600 °C, a very large degree of carbonation for such a material. Poor thermal stability of this material however meant that a full structural determination from refinement of XRD data could not be carried out. Additionally, further work is required to test the prepared materials in fields including carbon capture and wastewater treatment before this can truly be considered a viable route for carbon dioxide utilisation.