Effect of Microwave Irradiation on the Synthesis of Carbonated Hydroxyapatite (CHA) from Chicken Eggshell

Abstract

The main inorganic constituent of human bone is carbonated-hydroxyapatite (CHA). Chicken eggshells (CES) become potential waste which can be used for biomaterial synthesis because it contains of 94% calcium carbonate (CaCO3). This research aims to synthesize CHA by microwave assisted methods. CHA was successfully synthesized by mixing a calcium solution from CES with aqueous solution of NaHCO3 and H3PO4. Microwave assist offers many advantages such as fast reaction, easy reproducibility, high yield, high purity, efficient energy transformation, and throughout volume heating. After precipitation process, samples were irradiated in microwave oven for 30, 35, and 40 minutes by using microwave power 40, 200 and 400W. The functional groups of CHA powder was determined by FTIR. There are functional groups of phosphate (PO43-), hydroxyl (OH-), and carbonate (CO32-). The FTIR spectrum indicates that the prepared sample is B-type carbonated substituted HA because part of phosphate groups in the HA structure is replaced by carbonated groups. The phase composition was evaluated by XRD and indicated the presence of HA and CHA. The quantitative analysis showed that Ca/P ratio is 1.64, which indicates that the obtained product is non-stoichiometric HA. The successful synthesis of CHA is a critical step forward in our efforts to fabricate bone tissue engineering scaffold.