The effect of ball milling time on the phase stability and morphology of hydroxyapatite synthesized using calcium carbonate from biogenic waste

• Published in: AIP Conference Proceedings
• Main Author: Natasha A.N.; Atiqa A.F.; Nurul M.W.; Mardziah C.M.; Alexander C.H.C.
• Format: Conference paper
• Language: English
• Published: American Institute of Physics 2024
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85203970742&doi=10.1063%2f5.0229219&partnerID=40&md5=df73dee72807b52d51244b387ba4f075

Among calcium phosphates, Hydroxyapatite (HA) has become the material of choice and is commonly used in bone implantation and human teeth due to its chemical and crystal structure similar to bone apatite and excellent bioactivity. To date, HA has been successfully prepared from biogenic waste as the calcium precursor via extraction of calcium oxide from eggshells, seashells, animal bones (cow, chicken, fish) and many more via wet method. The dry method has been least preferred due to the tendency of powder contamination and non-homogeneous powder mixing during the mechanochemical activation method. However, with the proper methods, the dry method can be used in producing pure HA on a mass scale. Consequently, this work used a solid-state synthesis approach to produce HA from discarded eggshells, which provided a biogenic calcium precursor in the form of calcium carbonate. The intention was to determine how various ball milling durations affected the microstructure and phase stability of the artificially produced HA generated from eggshells. The eggshells were dried first and then subjected to calcination at 700°C for 2 hours. The eggshells, after being heated to high temperatures, were combined with dicalcium phosphate dihydrate (DCPD) by rotating at 400?rpm for 2, 4, and 6 hours. The powder combination including CaCO3 and DCPD was subjected to heat treatment at 800°C to get pure HA powder. The XRD analysis of the heat-treated powder revealed the successful production of hydroxyapatite (HA) after 2 hours of ball milling and calcination at 800°C. Extending the ball milling period to 4 hours and 6 hours would lead to intense mechanochemical activation, resulting in the powder combination transitioning into a biphasic calcium phosphate (BCP) phase including HA and β-TCP. Furthermore, the image of pure HA powder that was made after two hours of ball milling showed that the powder had a flake-like shape and was less clumped together. The BCP powder produced contained spherical particles that were agglomerated in form. The milling length of the starting materials significantly impacted the phase stability and microstructure of the synthesised calcium phosphate powder generated from eggshells. © 2024 AIP Publishing LLC.