In order to meet up the requirement for the safe disposal of high level radioactive waste, immobilization of Ba, Cd and Sb over the freshly prepared hydrothermally stable and dense type zirconium oxide is studied. Investigation about the adsorption of Ba, Cd and Sb at tracer level was undertaken with the hydrous zirconia, dried at 70"C for 24 h, and very high uptakes of 110 Ba (95.69%), 115 Cd (99.43%) and 125 Sb (95.18~;) were observed. Weighable quantities of Ba, Cd and Sb cations were separately precipitated alongwith zirconium-hydroxide and 46.5 16 for Ba, 58 ~0 for Cd and 53.0% for Sb were adsorbed respectively. After calcining the mixed mass in pellet form at 1,200"C for 20 h, soxhlet leach test at 97"C in every 24 h for 7 days showed the release of cations in the order of 10-7 g•cm-2 •d-1 • Surface area of the immobilizer pellet was determined by N 2 gas adsorption BET method. X-ray diffraction patterns have been also obtained for each of the zirconia samples accommodated with Ba, Cd and Sb, and distinct structural changes have been indicated.
Fe-montmorillonite (Na0.3Fe3+1.7Mg0.3Si4O10(OH)2·H2O) was synthesized hydrothermally for 24 hours at 100 and 200 °C. XRD analysis showed the synthesized material to be crystalline Fe-montmorillonite without impurities, with d001=11-14.3 Å and d06=1.52-1.53 Å, respectively. The particle size of the material was found to be > 500 Å by TEM. The X-ray photoelectron binding energy of Fe indicated that iron is present in smectite as Fe3+.
Sorption of Sr2+ ions on Na-montmorillonite was carried out in Sr2+ ions and in binary solutions of Sr2+ and Li+ ions at 220 °C for 24 h under hydrothermal condition. Sorption of Sr2+ ions was found to be substantially increased by the assistance of Li+ ions. FT-IR spectra revealed that migration of Li+ ions in the hexagonal hole of montmorillonite and subsequent exchange with Sr2+ ions affected OH-stretching bands caused an increase of Sr-sorption.
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