Modeling of ﬁxed-bed adsorption of Cs + and Sr 2+ onto clay–iron oxide composite using artiﬁcial neural network and constant–pattern wave approach Abderrahmane Ararem • Abdelkader Bouzidi • Brahim Mohamedi • Omar Bouras Received: 30 January 2014 Ó Akade ´miai Kiado ´, Budapest, Hungary 2014 Abstract A low-cost, non-toxic and effective adsorbent constituted by a montmorillonite coated by iron oxides (montmorillonite–iron oxide composite) was prepared to assess its effectiveness in the removal of Cs ? and Sr 2? from aqueous solution. Dynamic adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth Z (5–15 cm), initial cation concentration C 0 (2–50 mg L -1 ) and volumetric ﬂow rate Q (0.5–8 mL min -1 ). Column performance has been modeled with constant-pattern wave approach combined to the Freundlich isotherm model and artiﬁcial neural network (ANN) models. The time, initial cation concentration, bed depth and volumetric ﬂow rate were chosen as the input variables whereas, the outlet concentration C t was considered as the output variable. The developed network was found to be useful in predicting the breakthrough curves. Experimental data for the used sys- tem were well ﬁtted with ANN than the combined con- stant–pattern wave approach. Keywords Fixed-bed adsorption  Composite  Caesium  Strontium  Artiﬁcial neural network (ANN)  Wave theory  Modeling Introduction The development of industrial activities, using radioactive materials led to the release of a number of artiﬁcial ra- dionuclides in the environment, 137 Cs and 90 Sr are con- sidered to be the more critical isotopes, for several reasons: they exhibit high solubility, have long half-live (T 1/2 *30 years), and can be easily incorporated into terrestrial and aquatic organisms because of their chemical similarity to K and Ca, respectively. Their bioavailability depends mainly on sorption properties of the solid phases [1, 2]. As a conventional method for pollutants removal, adsorption has been developed as an efﬁcient and eco- nomical method for the removal of trace metals from wastewaters and water supplies. That is why a variety of adsorbents, including clays, zeolites, biopolymers, metal oxides, ﬂy ash and activated carbon have been used to remove Cs and Sr [3–6]. Clays or modiﬁed clays are used worldwide as adsorp- tive media for several heavy metals [7]. Chemical modi- ﬁcations on the surface of the clays with acids, bases, cationic surfactants and some poly hydroxyl cations were also conducted to improve their sorption capacities. It was reported that the intercalation of some metal oxides on 2:1 clay minerals signiﬁcantly led to an increase in the sorption capacity [8]. Over the last decade iron oxides have been recognized as being solid phases, which exert a signiﬁcant effect on the behavior of a large range of environmentally relevant substances particularly heavy metals and other toxic ele- ments, eutrophication compounds, and organic xenobiotics. In another way, they can immobilize pollutants by surface adsorption or by incorporation [9]. A successful design of a ﬁxed bed adsorption system depends on the model selected for this purpose. Therefore, A. Ararem (&)  A. Bouzidi  B. Mohamedi Nuclear Research Centre of Birine, BP180, 17200 Ain Oussera, Algeria e-mail: arareme@mail.com O. Bouras Saad Dahlab University, BP270, 09000 Blida, Algeria 123 J Radioanal Nucl Chem DOI 10.1007/s10967-014-3200-4