The Synthesis of Hydroxyapatite by Hydrothermal Process with Calcium Lactate Pentahydrate: The Effect of Reagent Concentrations, pH, Temperature, and Pressure

Hydroxyapatite and other calcium phosphates in the form of whiskers are lately widely considered as fillers for biocomposites due to their special biological and reinforcing properties. Depending on the method of synthesis, apatite whiskers of various sizes and phase composition can be obtained. In our work, hydroxyapatite (HAp) whiskers were successfully prepared in reaction between calcium lactate pentahydrate and orthophosphoric acid. The advantage of the proposed technique is the simple but precise control of the HAp crystal morphology and high product purity which is necessary for biomedical applications. The effect of reagent concentrations, pH, reaction temperature, and pressure on HAp whiskers' morphology and composition was investigated. In the result, we obtained hydroxyapatite of different morphology such as whiskers, hexagonal rods, and nanorods. The products were characterized by SEM, XRD, and FTIR. In this work, the synthesis of HAp whiskers by direct decomposition of calcium lactate pentahydrate chelates under hydrothermal conditions was showed for the first time.