Preparation and characterization of chitosan/Fe2O3 nano composite for the adsorption of thorium (IV) ion from aqueous solution

In this study, novel chitosan/Fe2O3 nano composite Ch/Fe-O-nc was synthesized and evaluated as an adsorbent for removing thorium (IV) (Th4+) ion from aqueous solution. The Ch/Fe-O-nc was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Response surface methodology (RSM) was used in the optimization of Th4+ adsorption for parameters such as pH, the initial metal ion concentration (Th4+ concentration) and contact time. The statistical measures (i.e. analysis of variance, R-2, the lack of fit test and the P value) specify that the developed model is proper. Furthermore, the adsorption kinetics was well defined by the pseudo-second-order equation, while the adsorption isotherms were better fitted by the Langmuir model. The adsorption capacity of Ch/Fe-O-nc was 430 mg Th4+ g(-1) composite which leads to 99% removal at 25 degrees C. Moreover, thermodynamic parameters which state the natural and endothermic nature of the reactions were determined. The loaded Th4+ can be easily regenerated with HNO3 and the Ch/Fe-O-nc can be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th4+ from the Ch/Fe-O-nc by using 0.1 M HNO3, was more than 95%.