A B S T R A C TThe adsorption of uranium (VI) from aqueous solutions on synthesised zeolite NaY has been studied and the effect of the solution pH, the initial concentration C, the solid/liquid ratio R and the temperature T was investigated. The adsorption process has been modelled using a 2 3 full factorial design in order to study the influence of the main effects and interaction parameters and to optimise the adsorption process. The pH is the most significant parameter affecting uranium (VI) ions' distribution on zeolite NaY. The equilibrium isotherm has been found to follow the Langmuir model. Kinetic studies showed that the pseudo-second-order model correlates our experimental data. Thermodynamic parameters showed the exothermic heat of adsorption and the spontaneity of the adsorption process.

The present work deals with the investigation of the use of the elaborated aluminophosphate (AlPO 4 -5) and silico-aluminophosphate (SAPO-5) materials, in uranium sorption from aqueous solution and real effluents obtained from Nuclear Research Center of Draria, Algiers, Algeria. The surface charge and acidic-basic character of AlPO 4 -5 and SAPO-5 is investigated by the determination of point of zero charge. Batch adsorption experimental studies are carried out to evaluate the influence of initial uranium concentration, final solution pH, contact time, solid-to-liquid ratio and temperature. A maximum adsorption capacity of 61.96 and 74.10 mg/g was obtained for AlPO 4 -5 and SAPO-5 respectively, at pH 7 with an adsorbent ratio of 0.1/150 g/ml and an equilibrium time of 120 min. Kinetic models (pseudo-first order, pseudo-second order and Weber-Morris) are applied to find the mechanism for the removal of uranium ions, experimental data are analyzed by equilibrium models (Langmuir, Freundlich, Dubinin-Radushkevich and Temkin). Modeling sorption results show that uranium sorption is a chemical and endothermic process. The results showed that AlPO 4 -5 and SAPO-5 are effective materials for the removal of uranium (VI) ions.