Equilibrium, isotherms and kinetic studies of uranium sorption onto AlPO$_{4}$-5 and SAPO-5 materials

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.