SELECTIVE REMOVAL OF CESIUM FROM RADIOACTIVE WASTE SOLUTIONS USING INSOLUBLE FERROCYANIDE-LOADED MORDENITES

摘要

Potassium nickel hexacyanoferrate(II)s (KNiFC) were incorporated in the porousrnmatrix of mordenites by successive impregnation of Ni(NO3)2 and K4Fe(CN)6. ThernKNiFC crystals with fcc structure were uniformly dispersed throughout the granule,rnresulting in the lowering of specific surface area and pore volume. The ion-exchangernequilibrium of Cs+ in KNiFC-loaded mordenite (NMFC) was reached within 2 days.rnRelatively large distribution coefficients of Cs+, Kd,Cs, above 104 cm~3/g werernobtained even in the presence of highly concentrated 5 M NaNO3 or 5 M HNO3.rnThere was a large difference between the Kd value of 137Cs and those of otherrnnuclides; separation factor of Cs/Sr (αCs/Sr= Kd,Cs/Kd,Sr) was estimated to be 104 inrnthe presence of 2.5 M HNO3-0.981 M NaNO3. Favorable S-shaped breakthroughrncurves for Cs+ were obtained by passing the simulated high-level liquid wastesrncontaining 29 components through the column packed with NMFC exchanger, andrnthe breakthrough capacity of Cs+ was estimated to be 0.19 mmol/g. This exchangerrnproved to be effective for the selective removal of radioactive cesium from highlevelrnliquid wastes.