THE EFFECTS OF CITRIC AND ACETIC-ACIDS ON THE FORMATION OF CALCIUM-DEFICIENT HYDROXYAPATITE AT 38-DEGREES-C

This study is concerned with the formation of calcium-deficient hydrox yapatite at physiological temperature. Isothermal calorimetry, solutio n chemistry, scanning electron microscopy, BET surface area analyses a nd FTIR spectroscopy were used to characterize the kinetics of HAp for mation and the microstructure of the HAp formed in varying concentrati ons of citric and acetic acids, and in deionized water. The kinetics o f HAp formation are a strong function of both the concentration and ty pe of acid. Acetic acid accelerates reaction due to pH effects. Citric acid retards HAp formation by citrate adsorption on the precursor and product phases. The results obtained indicate that hydroxyapatite for mation can be tailored to address the requirements needed for eventual clinical applications.