Characteristics of Carbonated Hydroxyapatite Based on Abalone Mussel Shells (Halioitis asinina) Synthesized by Precipitation Method with Aging Time Variations

Abstract

Carbonated Hydroxyapatite (CHAp) is a substituted-hydroxyapatite (HAp) with carbonate ions that are similar to natural inorganic bone constituents. The CHAp can be synthesized from natural material that has high calcium carbonate, such as abalone shells (Halioitis asinina), with a calcium carbonate content of 90-95% of the total abalone shell weight. In this study, the precipitation method has succeeded in synthesizing CHAp. The effect of aging time variations (0, 24, and 48 hours) during the synthesis process on CHAp characteristics was investigated. Characterization of the samples were conducted using X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDX), and Fourier Transform Infrared (FTIR). Based on XRD data analysis, the diffraction peaks at32.02° were observed in all variations of aging time, i.e., the characteristics of B-type CHAp phase, in which the increasing of aging time reduces its crystallinity. B-type CHAp was formed when carbonate ions substitute the phosphate ions in the structure of HAp, as confirmed by EDX analysis. This means that the increasing of aging time improves its Ca/P mole ratio (1.71-1.81), which is greater than the Ca/P mole ratio of stoichiometric HAp (1.67). This is due to an increase in the number of carbonate ions that replace the position of phosphate ions as aging time increases. This is also confirmed by FTIR analysis, which showed that the increasing of aging time cause stronger absorption of carbonate ion in 872.9 cm−1, characteristics to B-type CHAp. From data analysis, it can be concluded that 48 hours aging time was the optimum time to produce B-type CHAp which has similar characteristics to natural bone apatite with low crystallinity.