Hydroxyapatite (HA) is a calcium phosphate compound [Ca10(PO4)6(OH)2] which is non-toxic and has high biocompatibility. HA can be synthesized from natural basic ingredients with high calcium carbonate (CaCO3) content such as chicken eggshells. Here, we reported the synthesis of HA from chicken eggshells by hydrothermal methods. The effects of temperature synthesis of 120 °C and 230 °C on the purity and crystallinity were investigated in order to get information about best synthesis temperature for producing high quality of HA. The structure and crystallinity of HA were determined by XRD and FTIR. Morphology of HA is determined by TEM, while the composition was determined by XRF, respectively. High purity samples of HA with hexagonal structure of P63/m were successfully obtained with synthesis temperature of 120 °C and 230 °C. For HA synthesized in 120°C, the purity was 97.7%, while for HA synthesized in 230 °C, the purity was 97.8%. Two types of impurities, namely Ca(OH)2 and tricalcium phosphate (TCP) ware detected in both samples, It was also obtained the degree of crystallinity of 26.86% and 56.46% for samples synthesized at 120 °C and 230 °C, respectively. HA synthesized with at 230 °C has a higher and better crystallinity.

The hydrothermal method has effectively synthesized hydroxyapatite (HA). This study aimed to analyze the effect of pH on the properties (purity, crystallinity, and size) of HA crystals. HA synthesis of chicken eggshells was carried out using the hydrothermal method at temperatures of 230 °C with pH 9 and 9.34. The characteristics of HA are determined by XRF, XRD, FTIR, and TEM. The composition of the most significant compound obtained from the results of XRF analysis is CaO (97.5%). The XRD analysis showed that the purity of HA with pH 9.00 and 9.34 obtained was 97.8 and 96.6%, with the crystallinity of 56.46 and 56.96%. It was also obtained that the size of crystal HA was 21.8 and 15.7 nm for samples synthesized at pH 9.00 and 9.34. The results showed that the purity and size of HA were affected by differences in the pH synthesis and were relatively the same for its crystallinity which directly affects the value lattice parameter. The properties of HA produced by the hydrothermal method have met the criteria for biomedical applications.