Continuous precipitation of hydroxyapatite from Ca/citrate/phosphate solutions using microwave heating

fThe precipitation of hydroxyapatite (HAp) in a continuous process using mi crowave heating and Ca/citrate/phosphate solutions is presented. Calcium de ficient HAp particles in the nanometric size range (<100 nm), with needle-l ike morphology, were obtained. These chemical and morphological characteris tics do not change with the residence time, and are similar to those of HAp obtained in a batch process using also microwave heating and Ca/citrate/ph osphate solutions. On the other hand, the steady state is reached faster th an in the precipitation of HAp in a MSMPR reactor using non-complexing solu tions and conventional heating. In the latter process submicronic (< 1 mu m ) needle-like particles are obtained.