Comparative adsorption study of Th4+ from aqueous solution by hydrothermally synthesized iron and aluminum oxide nanoparticles

Comparative adsorption behaviors of synthesized iron nanoparticles (Fe-NPs) and aluminum nanoparticles (Al-NPs) on thorium(IV) (Th4+) ion from aqueous solution have been studied using batch system. Both Fe-NPs and Al-NPs were synthesized by hydrothermal method and characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, Brunauer–Emmett–Teller and Fourier transform infrared. The results showed that more than 90% of synthesized nanoparticles were in the size range of 7–100 nm, when the specific surface area of Fe-NPs and Al-NPs was found to be 126.1 and 37.4 m2 g−1, respectively. The influence of variables namely sorbent weight, contact time and pH on the adsorption of Th4+ ion was investigated. The pH dependence was observed in both Fe-NPs and Al-NPs adsorption processes, and the maximum adsorption occurred at pH 5 and 4, respectively. For both Fe-NPs and Al-NPs, kinetic data correspond well to the pseudo-second-order and the coefficient of determination (R2) indicates that the developed model is appropriate. In addition, for both Fe-NPs and Al-NPs, the adsorption data were well fitted by the Langmuir isotherm. The maximum adsorption percent and adsorption capacity for Fe-NPs and Al-NPs were found to be 98%; 595 mg g−1 and 95%; 602 mg g−1, respectively. In addition, thermodynamic parameters containing standard enthalpy, entropy, and Gibbs free energy were determined which point out the natural and endothermic nature of the reactions. Both nanoparticles show the good capability of Th4+ ion adsorption, although Fe-NPs is marginally better.