Hydroxyapatite from animal bones – Extraction and properties

Bovine bones were treated with aqueous solutions of NaOH and KOH in order to remove the organic parts. Such hydroxyapatite powders differ from each other by their particle sizes depending on the time of treatment and concentration of the extracting agent. It was found that prolonged time of treatment and increased hydroxides concentration led to the powders of smaller specific surface area and larger crystallite sizes. These observations as well as TEM investigations allowed us to conclude that the process of dissolution and crystallization occurs during the hydroxide treatment. Simultaneously structural changes occur; hydroxide groups become partially substituted for carbonate groups.