Fabrication of beta-cyclodextrin conjugated magnetic HNT/iron oxide composite for high-efficient decontamination of U(VI)

In this study, beta-cyclodextrin (beta-CD) was chemically grafted onto halloysite nanotube/iron oxides (HNT/iron oxides) to prepare a novel magnetic CD/HNT/iron oxide composite. The XRD pattern and FT-IR spectra analysis provide evidence for the successful grafting of beta-CD on HNT/iron oxide surfaces. Elemental analysis indicates that the grafted beta-CD amount in CD/HNT/iron oxide composite is 112 mg/g. Batch technique was adopted to investigate the removal efficiency of U(VI) from aqueous solutions by CD/HNT/iron oxide as a function of various environmental factors. The sorption reversibility and performance of CD/HNT/iron oxide in simulated effluent disposal were also tested. The sorption kinetic data can be well fitted by the pseudo-second-order model. The pH-dependent sorption suggests an optimal pH value of 7.0 for using CD/HNT/iron oxide in the decontamination of U(VI) from aqueous solutions. The sorption irreversibility at pH 5.5 was attributed to the inner-sphere binding of U(VI) on CD/HNT/iron oxide surface sites. The maximum sorption capacity of U(VI) on CD/HNT/iron oxide is considerably higher than that of some other reported materials. Related data show that CD/HNT/iron oxide exhibits satisfactory treatment efficiency for the simulated wastewater. It is worth noting that CD/HNT/iron oxide could be easily separated from aqueous solution by using a permanent magnet. By integrating the experimental results presented in this study, it is clear that CD/HNT/iron oxide can be potentially used as a cost-effective material for the purification of actual U(VI)-bearing effluents. (C) 2012 Elsevier B.V. All rights reserved.