FORMATION OF PALLADIUM PRECIPITATE BY HYDRAZINE IN A SIMULATED HIGH-LEVEL LIQUID WASTE

The formation of precipitates by hydrazine was experimentally examined in the simulated high level liquid waste (HLLW), which was composed o f 9 elements (Nd, Fe, Ni, Mo, Zr, Pd, Ru, Cs, Sr). Palladium was preci pitated over 90% above 0.05M of hydrazine concentration and at 2M HNO3 , while all of the other elements were hardly precipitated. The elemen ts of Pd and Zr were precipitated 93% and 70% in the simulated solutio n in which the concentrations of Zr and Mo were decreased from 0.069M to 3.45 . 10(-3)M and 6.9 . 10(-3)M, respectively, and the acid concen tration was decreased to about 0.5M after denitration. In a Pd solutio n of 0.5M and 2M HNO3, the precipitation yield of Pd increased with hy drazine concentration and reached over 98% at 0.1M. The precipitation yield of Pd at 0.5M HNO3 was higher than at 2M HNO3 The Pd precipitate , formed by adding hydrazine to an acidified solution, was an amorphou s compound consisting of Pd, hydrazine, nitrate and hydrate.