Dispersing behavior of hydroxyapatite powders produced by wet-chemical synthesis

Three hydroxyapatite powders with different surface properties were produced by wet-chemical synthesis and characterized. The electrokinetic properties of powders dispersed in water were investigated by electroacoustic spectroscopy measurements. The different surface reactivity (pHiep and z potential vs pH curves) was related to the interplay of dissolution and adsorption of Ca2+ ions. With a view toward the preparation of porous bodies by sponge impregnation, the behavior of powder suspensions was studied. Four deflocculants were tested and the optimum dispersing conditions for each powder were found. Anionic polyelectrolytes resulted the best effective dispersing agent, with different optimum amount added to the suspensions.