ELIMINATION OF PB2-SOLU TION BY USING CALCIUM HYDROXIDE SOLUTION OR AMMONIUM PHOSPHATE SOLUTION( ION FROM AQUEOUS)

The elimination of Pb2+ ion from aqueous solution was performed by add ing calcium hydroxide solution or ammonium phosphate solution to a sol ution containing Pb2+ ion, The concentration of the filtrate was measu red and the data were compared with those of the ferrite formation met hod. In the case of Ca(OH)(2) addition, the concentration of Pb2+ ion in the filtrate was affected by the Ca2+/Pb2+ ratio, The minimum conce ntration of 0.58 mg/dm(3) was obtained when the Ca2+/Pb2+ ratio was 1, where pH of the solution was 11.74, In the case of (NH4)(3)PO4 additi on, ill-crystallized Pb-hydroxyapatite was precipitated, and the conce ntration of Pb2+ ion in the filtrate was 0.01 mg/dm(3). The well-cryst allized Pb-hydroxyapatite was obtained by the hydrothermal treatment o f ill-crystallized one by using solution with pH of 12 at 150 degrees C for Ih. This Pb-hydroxyapatite has lower solubility than lead hydrox ide over a wide pH range, It is concluded that the method for eliminat ion of Pb2+ ion, from aqueous solution by using calcium hydroxide or a mmonium phosphate phate were more effective than the ferrite formation method.