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

Naima Bayou,Sihem Khemaissia,Zohra Bouhila,Hamid Aït-Amar,Samir Belkhiri,Tarek Azli,Fatima Houhoune

doi:10.5802/crchim.119

Abstract

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.

Highlights

Environmental pollution due to uranium has largely been as result of development of the nuclear industry [1]
The Point of zero charge (PZC) for AlPO4-5 and SAPO-5 used in the present study is found to be 5.00
AlPO4-5 and SAPO-5 fits well the pseudo-second order kinetics. These results suggest that uranium (VI) adsorption appears to be controlled by chemisorption process [30,31]

Summary

Introduction

Environmental pollution due to uranium has largely been as result of development of the nuclear industry [1]. Uranium is the most hazardous longlived radionuclide in the environment [2] For both human health security and environment protection, the removal of uranium is necessary [3,4,5]. Sorption is one of the promising technologies for the removal of toxic heavy metals [6,7,8] In this respect, many adsorbents are used such as zeolites and their derivatives [9,10,11,12,13,14,15,16]. The channel diameter of aluminophosphates-five materials (7.3 Å) is larger than the diameter of the hydrated uranyl (6.5 Å) which allowed a possible sorption of uranium by AlPO4-5 and SAPO-5 materials [20,21]. The experimental results are applied to the real effluents from Nuclear Research Center of Draria, Algiers, Algeria

Objectives

Methods

Results

Conclusion