Plasma synthesis of β-cyclodextrin/Al(OH)3 composites as adsorbents for removal of UO22+ from aqueous solutions

The beta-cyclodextrin/Al(OH)(3) composites (beta-CD/Al(OH)(3)) were synthesized using the plasma-induced grafting technique and were employed to remove U0i from aqueous solutions under ambient conditions. Based on the characteristic results of SEM, FT-IR, XRD, and TGA techniques, 13-CD was satisfactorily grafted onto the Al(OH)3 surface. The maximum adsorption capacity of beta-CD/Al(OH)(3) composites calculated from Langmuir model at pH 6.0 and 303 K was 6329 mg/g, which was significantly higher than Al(OH)(3) (2331 mg/g). The high adsorption capacity of beta-CD@AI(OH)(3) composites was due to the inner cores of the hydrophobic cavity of CD incorporated with UO22+ ions. The calculated thermodynamic parameters showed that the adsorption of UO3+ on Al(OH)(3) and E-CD@Al(OH)(3) composites was an endothermic and spontaneous process. The batch desorption indicated that the adsorption of UOi+ on f(3)-CD@Al(OH)(3) composites was an irreversible process. Based on the surface complexation modeling, the adsorption mechanism of UO3+ on Al(OH)(3) and E-CD@ Al(OH)(3) composites was outer-sphere surface complexafion at pH < 5.0, whereas inner-sphere surface complexanon dominated the UOP adsorption on Al(OH)(3) and E-CD@AI(OH)(3) composites at pH > 6.0. These observation showed that 13-CD/A1(OH)(3) composite can be used as a promising adsorbent for the preconcentration and immobilization of UO3+ ions in environmental pollution cleanup. (C) 2015 Elsevier BM All rights reserved.