Adsorptive removal of uranium(VI) from aqueous solutions by amino-functionalized montmorillonite@β-cyclodextrin composite

For economic and environmental security consideration, an amino-functionalized montmorillonite@β-cyclodextrin composite adsorbent (NH2-MMT@β-CD) was successfully synthesized to adsorb uranium(VI). NH2-MMT@β-CD performed excellent uranium(VI) removal performances with the uranium(VI) removal capacity of 469.4 mg/g, which was almost three times that of MMT. The reason for the improvement was that the introduction of 3-aminopropyltriethoxysilane and β-CD not only enhanced the d-spacing and surface roughness, but also brought abundant functional groups, like amino and hydroxyl groups, thus providing more useable active sites. Besides, NH2-MMT@β-CD also had good selectivity and favorable stability with the uranium(VI) removal efficiency of 90.4 % at the fifth cycle. Characterizations indicated that NH2-MMT@β-CD adsorbed uranium(VI) via electrostatic interaction, complexation, reduction reaction and ion-exchange. This work supplied a new idea for exploring novel clay-based adsorbents for selective and efficient removal and regeneration of uranium(VI) from aqueous solution.