Adsorption 9: 331–336, 2003 c  2003 Kluwer Academic Publishers. Manufactured in The Netherlands. Sorption Behaviour of Molybdenum on Different Antimonates Ion Exchangers I.M. EL-NAGGAR, E.A. MOWAFY, G.M. IBRAHIM AND H.F. ALY Atomic Energy Authority, P.O. Code 13759, Cairo, Egypt Received February 5, 2002; Revised May 19, 2003; Accepted June 3, 2003 Abstract. Various antimonate compounds are well known as important inorganic ion exchangers, since they resist radiation and chemical degradation and also exhibit selectivities towards different cations. Ceric, silicon, titanium and ferric antimonates were prepared as inorganic ion exchangers. Characterization of these materials has been described using different techniques, including thermal analysis, surface area measurements, X-ray diffraction and IR-spectroscopy. In batch distribution experiments the influence of HNO 3 molarity and Mo concentration for Mo sorption on different matrices is described in terms of their retention capacities and distribution coefficients.The selectivities of these exchangers towards molybdenum are in the order: CeSb > SiSb > FeSb > TiSb. Keywords: antimonates, sorption, ion exchange, selectivity, molybdenum Introduction Radioisotopes play an important role in the peaceful uses of atomic energy. The radioisotope most widely used in medicine is technetium-99m, employed in more than half of all nuclear medicine procedures. It is an isotope of the artificially produced element technetium and it has almost ideal characteristics for a nuclear medicine scan. It has a half-life of six hours, which is long enough to examine metabolic processes yet short enough to minimize the radiation dose to the patient (Lederer et al., 1967). Technetium-99m decays by an isomeric process in which gamma rays and low energy electrons are emitted. Since there is no high-energy beta emission, the radiation dose to the patient is low. The low energy gamma rays it emits easily escape the human body and are accurately detected by a gamma camera. Once again the radiation dose to the patient is minimized (Boyd, 1982). Since molybdenum-99m is the only source of short lived daughter, Tc-99m (Nair et al., 1992), the goal of this study was to develop a highly specific molybdenum separation method that would be used to get 99 Mo from a fission product mixture with exponentially high pu- rity. This process will mainly depend on the properties of the separating materials used. Many investigators continue to look for new inorganic ion exchange ma- terials whose special properties such as resistance to high temperature and radiation fields can be employed to advantage. The synthesis of inorganic ion exchangers has been studied by various workers (Clearfield, 1982). In a previous work, a number of new inorganic ion ex- changers which have useful properties were prepared. These prepared compounds have been found to be very useful in various radioisotopes separation (El-Naggar et al., 1994, 2002a, 2002b). Antimonate exchangers have been studied first by Abe and Ito (1967); cation exchange materials which contain antimony have very high hydrolytic stability in nitric acid (Pospelov et al., 1975) and show selective radionuclide uptake (Ibrahim, 2001) as well as actinides (El-Naggar et al., 1997) from nitric acid solutions. In this contribution, four dif- ferent antimonates ion exchangers (ceric, silicon, tita- nium and ferric antimonates) were prepared and char- acterized. The sorption behavior of molybdenum on these prepared antimonates ion exchangers were in- vestigated. In this work we will describe the influence