Highly efficient and selective extraction of uranium from aqueous solution using a magnetic device: succinyl-β-cyclodextrin-APTES@maghemite nanoparticles

Abstract

The removal of radio-elements, notably uranium, from wastewaters is crucial for public health and environmental remediation. To this end, succinyl-β-cyclodextrin (SβCD) is grafted onto maghemite nanoparticles (NPs) synthesized by a polyol method. The nanocomposite was characterized well. The adsorption of U(VI) by SβCD-APTES@Fe₂O₃ is pH-dependent with a maximum at pH 6. Adsorption occurs mainly by complex formation and displays a very good selectivity for U(VI) compared to other cations such as Cs⁺, K⁺, Na⁺, Mg²⁺ and Al³⁺. The data were plotted according to Langmuir, Freundlich, Elovich, Temkin and Halsey isotherms. The Langmuir isotherm maximum adsorption capacity (q_max) is 286 mg U per g and higher than that of other reported sorbents. Moreover, C_s-corrected STEM visualizes uranium on the NP surface, which is consistent with the Halsey isotherm model for multilayer adsorption. The U(VI) adsorbed on SβCD-APTES@Fe₂O₃ is easily recovered by magnetic sedimentation and desorption performed in a small volume in order to concentrate the extract. The nanocomposite can be regenerated and reused at least tenfold.