Immobilization technique of cesium by crystalline zirconium phosphate

HZr2(PO4)(3) was prepared by the thermal decomposition of NH4Zr2(PO4)(3), which was synthesized in advance by a hydrothermal reaction from a stirred solution of ZrOCl2, H3PO4 and H2C2O4. Mixtures of HZr2(PO4)(3) with varying amounts of CsNO3 were thermally treated at 873 similar to1,473K, in order to investigate the immobilization of radioactive Cs. The CsNO3/HZr2(PO4)(3)=0.4 immobilized product, treated at 973K, containing the maximum amount of immobilized Cs (a 0.4 molar ratio of CsNO3/HZr2(PO4)(3) equates to approximately 10wt% of Cs) was minimal Cs leaching rates in several solvents at 433K in an autoclave. The leaching rate of Cs ion from that product was < 10(-6), 1.0 X 10(-3), < 10(-6), < 10(-6), 4.7 X 10(-5), 2.2 X 10 (4) and 2.1 X 10 (3) g(.)M (2.)d (1) in deionized water, sea water, 0.1 mol(.)dm(-3)-HCl, 0.5 mol(.)dm(-3)-HCl, 1 mol(.)dm(-3)-HCl, 1.5 mol(.)dm(-3)-HCl and 1 mol(.)dm (-3) -NH3 at 433K, respectively, indicating that HZr2(PO4)(3) reacts with CsNO3 to give a stable Cs-immobilized product.