FTIR and TPD studies on the adsorption of pyridine, n-butylamine and acetic acid on calcium hydroxyapatite

Colloidal calcium hydroxyapatite (CaHAP) particles synthesized by a wet method and calcined at different temperatures up to 900 degrees C have been characterized by various means. The adsorption species and sites on the CaHAP surface for pyridine, n-butylamine and acetic acid were clarified by FTIR and TPD. These molecules were shown to be adsorbed by hydrogen-bonding to the surface P-OH groups. The surface P-OH groups of CaHAP were removed by outgassing above 600 degrees C to produce surface P-O-P groups. The n-butylamine is hydrogen bonded to the surface P-O-P species.