JJEES Volume 2, (Special Publication, Number 1), December. 2009 ISSN 1995-6681 Pages 108- 119 Jordan Journal of Earth and Environmental Sciences Adsorption of Thorium (IV) and Uranium (VI) by Tulul al- Shabba Zeolitic Tuff, Jordan Mona Al-Shaybe and Fawwaz Khalili* University of Jordan, Chemistry Department, Amman – Jordan Abstract Tulul al-Shabba zeolite from Jordan was employed to remove actinides metal ions namely Uranium (VI) and Thorium (IV). The used Jordanian zeolitic tuff is dominated by phillipsite and chabazite. The sorption behavior of the used zeolitic tuff towards Th 4+ and UO 2 2+ metal(s) ions in aqueous solutions was studied by batch experiment as a function of pH, contact time and temperature and column techniques at 25.0°C and pH= 3. High initial rate of metal ions uptake was observed after 24 hr of shaking, and the uptake have increased with increasing pH and have reached a maximum at pH = 3. Tulul al-Shabba zeolitic tuff has shown high metal ion uptake capacity toward Thorium (IV) than Uranium (VI). Adsorption data was evaluated according to the Pseudo second-order reaction kinetic. Adsorption isotherms were studied at temperature 25C°, 35C° and 45C°. The Langmuir, Freundlich and Dubinin- Raduskevich (D-R) adsorption models equations were applied, and the proper constants were derived. It was found that the adsorptivity process is enthalpy driven for Thorium (IV) and Uranium (VI). Recovery of Thorium (IV) and Uranium (VI) ions after adsorption was carried out by treatment of the loaded zeolitic tuff in the column with 0.1N HNO 3 , 0.1N H 2 SO 4 , 0.1 - 1*10 -4 N EDTA, and 0.1N sodium acetate. The best percent recovery for Thorium (IV) was obtained when 1*10 -4 N EDTA was used, while for Uranium (VI) when 0.1N H 2 SO 4 was used. © 2009 Jordan Journal of Earth and Environmental Sciences. All rights reserved Keywords Jordanian zeolitic tuff, Thorium (IV), Uranium (VI), adsorption, isotherm, kinetic, recovery. 1. Introduction * Jordan is rich in industrial rocks and minerals. Zeolitic tuff is widely distributed in Jordan (Khoury et al., 2003). The huge reserves of the zeolitic tuff have encouraged the authors to carry out this work since investment projects of radioactive minerals have a priority in Jordan. Uranium is enriched in the Phosphorite and Chalk Marl Units of central Jordan (Daba-Siwaqa area 60 km south of Amman). The area is currently under investigation by Areva Co., and huge reserves are expected. UO 2 concentrations range between 140 – 2200 ppm in central Jordan. Thorium is associated with the Dubaydib Sandstone Formation, southern Jordan, where the level of thorium oxide reaches 400 ppm (Khoury, 2006). The methods for separation, collection and detection of radionuclides are similar to ordinary analytical procedures and employ many of the chemical and physical principles that apply to the non-radioactive nuclides. However, some important aspects of the behavior of radionuclides are significantly different, resulting in challenges to the radio chemists to find means for isolation of a pure sample for analysis. There are many methods for the separation and purification of radionuclides. The oldest method, used in the large-scale separation of actinides, is the precipitation * Corresponding author. fkhalili@ju.edu.jo technique. However, this process produces complex products and impure substances. Many ion-exchange separations of radionuclides are based on the formation of complex species between the metal and an extractant in the organic phase as in the extraction of Europium (III), Thorium(IV) and Uranium(VI) with didodecylphosphoric acid (HDDPA), (Kondo et al.1989); (Nazzal, 2006); (Khaled and Khalili, 1999). The use of solids for removing substances from either gaseous or liquid solution has been widely used since biblical times. This process, known as adsorption, involves nothing more than the preferential partitioning of substances from the gaseous or liquid phase onto the surface of solid substrate. From the early days of using bone char for decolorization of sugar solutions and other foods to the later implementation of activated carbon for removing nerve gases from the battlefield and to today’s thousands of applications, the adsorption phenomenon has become a useful tool for purification and separation (Slejko, 1985 and Lazaridis et al., 2004). Ion exchange is a process by which ions held in a porous, essentially insoluble solid exchange for ions in a solution that is brought in contact with solid. The ion exchange properties of clays and zeolite have been recognized and studied for more than a century (Skoog et al.1994); (Harvey, 2000). The main advantages of ion exchange over chemical precipitation are removal of metal value, selectivity, and less sludge volume produced- meeting the strict discharge specifications. In ion exchange system, polymeric resins as well as zeolite are usually