PREPARATION OF SPHER1CAL APATlTE PARTICLES BY THE HOMOGENEOUS PRECIPITATION METHOD IN THE PRESENCE OF MAGNESIUM IONS AND THEIR ION-EXCHANGE PROPERTIES

摘要

Spherical apatite particles were prepared by the homogeneous precipitation method in the presence of magnesium ions. The starting solutions were prepared by mixing 0.l67 mol.L~-l of Ca(NO_3)_2, 0.l00 mol.L~-l of (NH_4)zHPO_4, l .00 mol.Lu~-l of (NH_2)_2CO, 0.10 mol.L~-1 of HNO_3, and a small amount of Mg(NO_3)_2. The carbonate-containing apatite powders were ob- tained by heating these solutions at 80～95deg.C for 48～l92 h. Although fibrous particles with long-axis lengths of 30 to 60 um were obtained from the magnesium-free solution, spherical agglomerates with diameters of ～ l0 um, which contained minute plate-like particles, were present in the apatite pow- ders derived from the solutions with 5 mass/100 of magnesium ions. The ion-exchange test for the harmful ions (Pb~2+, Cd~2+, and Ni~2+) showed that the ion-exchange abilities of the apatite powders containing magnesium ions were much better than the ability of the magnesium-free apatite powder. The ion-exchanged amounts of the apatite powder containing magnesium ions were arranged in the following order: Pb~2+ Cd~2+ > Ni~2+.