Synthesis and structure of hydroxyapatite/tannin composites

Abstract

Hydroxyapatite (HA)-tannin composites were obtained by precipitation using Ca(OH)2 as calcium precursor and (NH4)2HPO4 or H3PO4 as phosphate precursors, with tannin acting as a chelating agent. FT-IR confirmed the presence of functional groups derived from tannin in the composite, and XRD showed trace amounts of calcium carbonate. The crystal sizes of HA and HA/tannin were 15–27 nm and 10–29 nm, respectively. SEM showed agglomeration of HA and HA/tannin particles. The size distribution of HA particles was in the range of 0.1–0.2 µm (without tannin), and the size distribution of HA/tannin particles in the range of 0.1–0.4 µm. The obtained results confirmed the formation of strong bonds between tannin and HA.