NEUTRALIZATION SYNTHESIS OF PURE HYDROXYA PATITE USING ORTHOPHOSPHORIC ACID AND CALCITE

It is possible to prepare calcium hydroxyapatite by reaction of phosph oric acid with calcium hydroxide or calcium carbonate. The physico-che mical study of the precipitate shows that the first method with calciu m hydroxide, at room temperature, forms after heating at 900 degrees C an apatite mixed with tricalcium phosphate. The second reaction, with calcite, forms at the beginning a mixture of apatite and calcite whic h goes through a B-type carbonated apatite and finally forms an hydrox yapatite after a long maturation under constant stirring in a nitrogen atmosphere.